THE NEW YORK ACADEMY OF SCIENCES

(Lyceum or Naturat History, 1817-1876)

Orricers, 1914

President—Grorert Freperick Kunz

Vice-Presidents—CHARLES P. BerkEy, RaymMonp C. Ospurn,

CHARLES BASKERVILLE, CLARK \WISSLER

Corresponding Secretary—HeEnry EK. Crampron, American Museum

Recording Secretary—Epmunp Oris Hovey, American Museum

Henry L. Donertry, 60 Wall Street

Librarian—Rauen W. Tower, American Museum

Treasurer

Yditor—EpMUND Otis Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

Chairman—Ciuartes P. Berkey, Columbia University

Secretary—A. B. Pacint, 147 Varick Street

SECTION OF BIOLOGY

Chairman—RayMonp C. Ospurn, 557 West 124th Street

Secretary—Witiiam K. Grecory, American Museum

SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY

Chairman—Cuar Es BaskerviILLE, College of the City of New York

Secretary—ERNeEstv E. Smiru, 50 Hast 41st Street

SECTION OF ANTHROPOLOGY AND PSYCHOLOGY

Chairman—Cuark WissterR, American Museum

Secretary—Rosert H. Low1e, American Museum

CONTENTS OF VOLUME XXIV

Page

ARMAS TOROS His tency Sina DOG SCV ISIE B Gacy OS Oe CLORG CLR OG CLERCR ORI ere RATE EEE Ee i

KOPTTN COTS spare yee ev ayrot stows) octiay/oi he Ne en lewne crete fs aravepetsaty sista ic aS einy siete suns Aa dadhget evaiaresoate li

WOmMPemlsmeerspvershayercie re renciere ustetevorenscete parade reieds [age eieve cvelevcls alobercharvis;avensiiecaye Shsichelehate ili

DaAtesrolLublication land Hdittons of Brochures... sc ckeeees seen iii

PATS CeO Pe UL UTS GT LL OMS repeyen cacy tore te cote ver eretate tayaial se Malloteveleis lors! cna eek ovelisralete late. cicharavers caciets iv

‘The Use of Crinoid Arms in Studies of Phylogeny. By Etvira Woop.

(GIEAICY eye DESMO) Vee eacie Ges pus GO OCG CORSO CG CRO AIO RID ERIC TOR aE ERE Cee eas ae 1

INoteston Camarasaurus Cope. By Cs C2 Mook... oe-es cece csc seee 19

The Genesis of Antigorite and Tale. By ALrexis A. JULIEN. (Plate VI).. 23

A Study of the Changes in the Distribution of Temperature in Europe and

North America During the Years 1900 to 1909. By HenryxK Arc-

TONKS gg ab lidatag enol wale UNIS S Cine aey OR RENCE CUP On ca COL M CIERONCITS CRT DORE) ce RARE ene airs 39

The Genesis of Certain Paleozoic Interbedded Iron Ore Deposits. By

VAY MOND > AR TEM TED BARGE (ETaAtes: Vill Xexel)ies os eee eiaiscaces oe ala loss

Chimateyandeb volition assy. We Ds VUAT TED Wee) eteescis ose cin circa 171:

Development of the Neuraxis in the Domestic Cat to the Stage of Twenty-

one Somites. By H. von W. ScHULTE and FREDERICK TILNEY. (Plates

ERENT NON) Maerpat Re cvecaeepencn che Pe havea ae Me ater eter owl ara tees ce sobate Wy austen Ne 319

Records of Meetings, 1914. By EpmMuNp Oris HOVEY............---ccees 347

herOrecamizawdonworpliewNCcademys cece aera atsloieer ace eee cee 407

AM rey" OreieTu oka U ClM ATE ENE 6 ke cas Sere CRORE SIE cn: OItEy CE SE REPO ENG I eR oes 407

OTe reO tal COME sree sewers eters Se ecope nee icee ten eek eteca cal oy he wit Svote idcasc dhe cheno 409

FATING TUG E Clin W INANE CIgerspa ete geeeste cy nes a ercltoy el sete areca theta gis oes ices MeLe lobe teeey ose aS 410

Wom SEUGU CLOTS ene patet penetek oror ter atovoicis ot fo Gt orate eet otk eee MSE aa tan ee 413

ESV VARW Sleeper ch artasvonreu renee neret ere Reve ares vareue pecs Ven) tee soe hcp omnia ar ei cies avehaves craven 414

MembershipsWistss 31s) ecember sl 914 yess 5 2.0 scicineio ccs oaie ide aera 421

MITRE CNA eat crencexs crete srate arse MC MEy Se LeTRG tel ete ete: ah ae wr aren ep eile s. Shoe Siatewithe ns wise eens 433,

DATES OF PUBLICATION AND EDITIONS OF THE BROCHURES.

Edition.

Pp. 1-17, 1 May, 1914. 1100 copies.

Pp. 19-22, 21 May. 1914. 1150 copies.

Pp. 23-38, 25 July, 1914. 1500 copies.

Pp. 39-113, 27 June, 1914. 1200 copies.

Pp. 115-170, 4 August, 1914. 1250 copies.

Pp. 171-318, 18 February, 1915. 1250 copies.

Pp. 319-346, 31; March, 1915. 1850 copies.

Pp. 347-443, 14 May, 1915. 1000 copies.

LIST OF ILLUSTRATIONS

Plates

I.—Cactocrini, Individual specimens.

11.—Cactocrini, Details of plates.

I11.—Cactocrini, Details of plates.

IV.—Cactocrini, Details of plates.

V.— Cactocrini, Details of plates.

VI.—Laminated Chrysotile-Asbestos from Thedford, Canada.

VII.—Map showing the Distribution of Clinton Hematites in the United

States.

VIII.—Fossil Ore.

[X.—Fossil Ore—Photomicrographs.

X.—O6litie Ore.

XI.—Cavernous Consolidation.

XII.—Special Consolidations.

XIITI.—Special Consolidations.

XTV.—Partial Impregnation.

XV.—Cherty Limestone Seams.

XVI.—Fossil Ore—Photomicrographs.

XVII.—Contact Specimens.

XVIIT.—Mud Cracks.

XIX.—Contact Specimens.

XX.—Contact Specimens.

XXI.—O56litic Ore—Photomicrographs.

XXII.—Sections of Embryos before and after Segmentation.

XXIII.—Sections of Embryos with Two and Three Somites.

XXIV.—Transverse Section, Embryo of Four Somites.

XXV.—Transverse Section, Embryo of Four Somites.

XXVI.—Transverse Section, Hmbryo of Four Somites.

XXVII.—Reconstruction of Neuraxis of Embryos of Four and fight

Somites.

XXVIII.—Transverse Section, Embryo of Eight Somites.

XXIX.—Transverse Section, Embryo of Eight Somites.

XXX.—Transverse Section, Embryo of Hight Somites.

XXXI.—Reconstruction of Neuraxis of Embryo of Nine Somites.

XXXII.—Reconstruction of Neuraxis of Embryo of Ten Somites.

XXXIII.—Reconstruction of Neuraxis of Embryo of Twelve Somites.

XXIV.—Reconstruction of Neuraxis of Embryo of Fourteen Somites.

XXXV.—Reconstruction of Neuraxis of Embryo of Sixteen Somites.

XXXVI.—Reconstruction of Neuraxis of Embryo of Seventeen Somites.

XXXVII.—Reconstruction of Neuraxis of Embryo of Nineteen Somites.

XXXVIII.—Reconstruction of Neuraxis of Hmbryo of Twenty-one Somites.

XXXIX.—Reconstruction of Portions of Neuraxis of Embryos of Fight and

Nine Somites.

XL.—Reconstruction of Portions of Neuraxis of Embryos of Twelve

and Twenty-one Somites.

XLI.—Transverse Section of Embryo of Sixteen Somites.

Text Figures

Page

Relationship of species of Cactocrinus and Teleiocrinus...... 002200000 srl

FRESTOLALONN OM OCMAnASOILIUSs DV) | COMC a aieiersieie ciclclete leis ele oreieice w/e ssieleeyslcl oe « 2

Diagrams of consecutive annual and consecutive monthly means of tem-

SSrRIKD ‘en AECL o na cooodooo6 bon dDo goo SG oud ODODE dye aisles letersret sheets 43,

Mica eNO, WEIS SIUSSI 55 octinadoo pobdomouboonnMedodG UOoo DOS OD Ee Dodo oC 47

Wineraaleion, asirntsailststss aocadcccocddeuccs cp odbnoou Nn doo cdbooFoDUGouOOdG AT

MACROMELONE TL SSO LESSON coe chasieiete cae iere eiavelsiettyalions) mleh easelayenchisvereccislsieenajerereealersiete 47

IM Daxerxoncoenoyo,~ AUST ILATNSHI) (Et Sao dio Goo 010 b bind UG OU Clin OIsIO-G.0 OG OD Odo toi CON AT

Wirveraalencm, IESBBEI IE, 3.65 g4¢cucssondbaccbobsoouucod ban CUO ODO UQSINOOUL 48

IMECODLELOT lS O4— 1 OOS eres terete tepeteneteieys eveols. a1 re/ eheilelieVxreusl olo\lelistavelal sic! opeleieile) « 48

MIAICEOPLELO ML gO — MOO Ae acta crakear eer iste yet irene speleyeve lovelci shel ats alctereyetaliereie es cle ekaile 48

Wilreeoyollerorn, TESTES: Ga Gb aaobucoo0 op udhooedodugeoouUoUUoUdcrodoE ONGC 48

Curves of the consecutive means at Bucharest, Odessa, Warsaw, Kazan

enol Angee fon CH). Ga motta cio tomo Od Clo cio Jind Ue Ole DOO EL aaOORp SOO Oe see 62

Consecutive temperature curves at Geneva, Aachen, Vestervig, Bodo,

ley oeNe Gua Syohmumiikyey tio chooks ouoeadanDOnCoUnoob oso oanoO uC 63

Temperature departures: form che, year ml GOO Me ere ceteusrele¥eice cc lelaieiele a oleie eielere 66

Memperavunrerdepanhunes for the year OOM ier cals cieie ciel -lels ici alelel siecle s 66

Nemperaturerdepartures stor thel year DOOD wesw yaralacy='<) hc «iste isle s) sisicre srieisc 67

Memperatunre.departures! fom the year LOOSE: cs cies siewicisis cece s sieve cvsl oi eele oe 67

Temperature departures tor! they years L904 ss 25 i535 oes ctelsteisic cialn ats eels). oe = 69

Memperatune;departunes: for they year 905. . 2a)... os). sverne clas sisis se elo leuers 69

Remperatunendepartures) for ithe yea L9OG Es. c1cc ses che lernialotel alete te atcvsiclsteleisie le 70

RNemperatunesdeparthurespror tne yieat OOM cia crates iclele <iskelsiale cleie » crcresciiee 70

Temperature departures for the year 1908........... Sicuaessyalo vs Stabe a seay ale eats 72

Memperatwresdeparkunes torcthe ryveat WOOO. ciycios a clcincisrels cist cleacie ciate selec a2

MemperaniTrecdepartunesy tor the year OOO ciacviaiwls ers sisters e ofere orcio ove evele eels 80

Memneratucexdepartures tor the year OOM 2. cn smccice «cece ere cine ene see 80

Memperaturedepartures tor ther year! TOO2 2 35. a2... ele terctelosis) eel oiele e eree 81

MemperaburerdeparhuTresstor Chey yea 1903 a. «avo ere cielo eleievele ote eisie stelcclere 81

Moemperature departures stor thel year L904 as. . tiers oe cee close s vlelc wen crore 83

Hemperature departures for the year 1905.6 ..0- sess cseeeseeaees cos 83

Temperature: departures; for the year L906... ce sacse sec ccc oe oo cele ice, S4

PWemperature departures! for the year 1907. oo5.. 3. cc.. sc cec ccc eer Savers 84

Memperatune departures for the year 19082. va... dacs cscs cesses ccc sess 86

Memperatnne: departuresstor the year lO09 ao.) .ti.. 2c caso 215 cleie aletene ss gioele S86

Successive positions of the quasinormal line..... COIN Be oe Ad oid OBE OA te 89

Progressive displacements of the antipleion of 1901..................... 89

Displacements of the quasinormal line....... sbienslay nushoiaverosrsin revels Boar 7 90

Departures of temperature averages for October, 1902,.—September, 1903.. 90

Departures of temperature averages for November, 1902,—October, 1903... 90

Departures of temperature averages for December, 1902,-November, 1903. 90

Departures of temperature averages for February, 1903,January, 1904... 91

Departures of temperature averages for March, 1903,—February, 1904..... 91

Departures of temperature averages for April, 1903—March, 1904..... ae ed

Departures of temperature averages for May, 1903,—April, 1904........... 91

Departures of temperature averages for March, 1904—February, 1905..... 92

Departures of temperature averages for July, 1904,—June, 1905........... 92

Teat Figures—Continued

Departures of temperature averages for January—December, 1905.........

Departures of temperature averages for February, 1905,-January, 1906...

Departures of temperature averages for January—December, 1906........

Departures of temperature averages for February, 1906—January, 1907..

Departures of temperature averages for April, 1906—March, 1907.........

Departures of temperature averages for June, 1906,—May, 1907.......... ,

Displacements of the quasinormal line on the corSecutive departure maps

of February, 1907, January, 1908, until July, 1907—June, 1908.......

EL CLOMIE ATI CMLCIN) ULOING fen ee vsouel=. ste etoye alc) «!/s\a1 = (ois inhsvole'lousleya total memetaneeeteiems Sano be

Pleionian amplitudes and the Arequipa curve................ Sif Joye tet stoteveyats

Consecutive temperature curves of Atlantic coast stations.............. -

Temperature variation of Montana (Miles City) compared with that of

PSMA AIS OL) vicc.cser050 cis «0. = wuss re lois es. sles Sus tticsayetenctetens: oloketeheneRever orate A

Temperature variations in Montana, Nebraska, Kansas and Louisiana....

Comparison of variations in California and Texas with the Arequipa

QUIEVE “So ad Had Od Ge CRA IO Ce aa: od aap etereees eure es dee fo) a eitdseere eee

Temperature variations in Greenland, Icel ia ae MAT OC 2. ls) < accvexcteke ieee

Temperature variations in Newfoundland and Maine. eteits,loeseheheretersascacs fake

Temperature variations in the Azores, Madeira and cape nuts islands!

Temperature curves at St. Helena, Arequipa, Porto Rico and Bermuda.

Pleronian "COnMeECHONS: «2.20.0. .6. 2s siis (els ave chal ats toveua ane oie a Siz\fol wists avs loge oreseneleue

Zoological regions on north polar projection..... Dapeovene caves vs ayers, abet ouenevenene

DHE Southern) continents: south polar pProjectiomerss serie ciciescielcle creer ore

Cross-section of continental platforms and ocean basins at 45° north lati-

TUGON TS ero 2's 6 0.0 OOO CES CIEREIe Sitase, Sle lailel awash arat epowen ere eeezsne Pons ieletenetans caesar Syren

Cross-section of eoruinental platforms and ocean basins at the equator. .

Characteristic features of the mammal faunre in different zodlogical re-

gions at successive epochs of the Cenozoic......... Tarte) diva tatenbeiey dh sie Feet eres

Dispersal and distribution of the principal races of man.................

Disnpersaleof the Primates... .2<.0.ccces sean 515 Se ca yayoveye tera taney e rotons wane nents

Phylogenetic relations of the living and extinct groups of Primates.......

Distribution of modern Canide....:....... Sirava Nova Nevahioeueneleteteie ke (caekeile ohtek rere rat

*alzearctic, but now surviving chiefly in the peripheral regions......

Distribution of the Urside, Pleistocene and Recent.................-.e--

Distribution of Noricide# and of Talpid&e..... 0.0%. sce. 2 Seemed Vere Aid Ono c

Distribution of Geomyoidea, Anomaluridie aaa Pedetid se cky.racie.cc: che orteoene

Distribution of the true Porcupines (Hystricidse) and New World Poreu-

pines (Drethizontide) .......... Sieh sy eKels! Bicus otoisieons tate ie eieKore etalascheyer stone

Distribution of the Neotropical families of Hystricomorphs............

Dispersal and distribution of the Perissodactyla. .

Distribution of quidee, living and Pleistocene :

Geologic range and phylogenetic relations of fossil Equidze............. f

Distribution of the Tapirs, living and Pleistocene. .

Distribution of the Rhinoceroses, living and Pleistocene. .

Distribution of Pigs and TPeccaries..... ,

The dispersal center of the Camelidze was in North America.....

Distribution of Cervidse and pro-Cervid Tragulidie

©) 0.0),0 (o./0\'m) a\,04 0 eini.a: Nie! .e: OK

Teat Figures—Continued

Page

Distribution of the Bovidie, existing and extinct.......... sate, eu taete ierense 248

Distribution of the Giraffes, existing and extinct............ ehavater atc tavete tate 249

Distribution of the Anthracotheres and Hippopotami.................... 252,

Phylogeny and distribution of the Artiodactyla....... SNe ha ratone ewoleets epatietso eee

Relationship of the Condylarthra to the Notoungulate and Supa eaiate

CTOUP SRO NOOLed pmMAaMM ALS eye elekel-ieietsty ester Sie evacMtal suet avebekerereral aye 257

Distribution of the Edentate orders............. aiehe elerere Byer sles ereterehons) ai . 259

Distribution and phylogeny of Xenarthra and Teeniodonta............... 260

Listribution of, Marsupials. 5. 22... aitatiasss BRO ica Neer te ee erie 263

Distribution of the Crocodilidw.............. Bua tehiat Mowe ato haus oblast ate, ech elon rece 285

DIStD UOMO DHTees tamil eSoft OAT epspotsnensicyaleias ets itcisiaciereieevere ers clsicre era aie 296

Schema of the composition of the encephalon in terms of basal and alar

DIAGESMOle ELIS cpio r.7-) SESS One Ct ioe SS bE Oe ana RRC toate eet ta i 56. iste)

Schema of the composition of the enGeaialon in terms of basal and alar

Dlatessand. canclioniG ZONE. ccs eee sede eo ae soe A ere es Sere ot Tat)

’

ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIV, pp. I-17, pll. I-V

Editor, EpmMunD OtTIs Hovey

THE USE OF CRINOID ARMS IN STUDIES

OF PHYLOGENY |

Eivira Woop

: NEW YORK

PUBLISHED BY THE ACADEMY

1 May, 1914

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum or Natura History, 1817-1876)

Orricers, 1914

President—Grorcrk Freprertck Kunz, 601 West 110th Street

Vice-Presidents—CuaArtLrES P. Berkey, RayMonp C. OsBurN,

CHARLES BASKERVILLE, CLARK WISSLER

Corresponding Secretary—HeEnry E. Crampton, American Museum

Recording Secretary—EpmuNnvD Oris Hovey, American Museum

Treasurer—Hrnry L. Donerty, 60 Wall Street

TAbrarian—Rartrn W. Tower, American Museum

Editor—Epmunv Ot1s Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

Chairman—Cuar tts P. BerKkety, Columbia University

Secretary—A. B. Pactnt, 147 Varick Street

SECTION OF BIOLOGY

Chairman—Raymonpd C. Ospurn, 557 West 124th Street

Secretary—Wi.uiamM K. Grecory, American Museum

SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY

Chairman—CHArtEs BASKERVILLE, College of the City of New York

Secretary—Ernest BE. Smiru, 50 Hast 41st Street

SECTION OF ANTHROPOLOGY AND PSYCHOLOGY

Chairman—CuLarKk WissLer, American Museum

Secretary—NRoxsrrr H. Lowrr, American Museum .

The sessions of the Academy are held on Monday evenings at 8:15

o'clock from October to May, inclusive, at the American. Museum of

Natural History, 77th Street and Central Park, West.

[ANNALS N. Y. Acap. Scr., Vol. XXIV, pp. 1-17, Pll. I-V.

1 May, 1914]

THE USE OF CRINOID ARMS IN STUDIES OF PHYLOGENY *

By Envira Woop

(Presented by title before the Academy, 2 March, 1914)

CONTENTS

ptROG UGE Ost aN yee eP EIN Ise pee tee etek ices o baa'y oi Shae ieieiewia e's ene ees

Description of Cactocrinus and six species of the genus.............--.--

Comparison of the preceding six speCieS.............22.-2-tesee rece eens

The Cactocrinus multibrachtatws series... 2... -0-. 22. 55s eee ee eee ee eee

Comparison of the preceding three species. .............-..2:2e-eeeeeeee

Relatronvor © CCLOCHINUS LO ELOLOCTUNALS ne 2-12 eters eiciiete © ee © oe crene oo ee eee

OTGITEIOM. > ble 38 2 os Gee OOO mace DOING IgE gon Co ole Onan Chieinr sori ats

‘

INTRODUCTION

In studying the phylogeny of Paleozoic crinoids, the worker is greatly

hampered by the difficulty of obtaining information about the early stages

in ontogeny. By the time the young crinoid is sufficiently calcified to be

preserved in the fossil state, the calyx has nearly, if not quite, all the

plates which are to be present in the adult. This fact is illustrated by

a calyx of Batocrinus subequalis only 4 millimeters in height which pos-

sesses all the plates of the adult, with the full number of arms and a

well-developed tegmen and anal tube. The present paper is concerned

with results which were obtained from a study of adult, or of late neanic

stages of camerate crinoids.

In order to determine the exact amount and character of the varia-

tion occurring in the number and arrangement of calyx plates, about one

hundred specimens of Batocrinus and Cactocrinus were examined and

the position of each plate carefully recorded. From this investigation, it

was found that there is very little variation in the plates concerned in the

‘support of the arms. In the specimens of Cactocrinus examined, the only

variation in the radial series was found to be due to the presence of an

extra arm or one arm less than the normal number for the ray, necessi-

tating a greater or smaller number of plates in the calyx. In each case,

‘the plates present followed the normal order for a similar ray or half ray

1 Manuscript received by the Editor, 4 February, 1914.

(1)

LIBRARY

NEW YOR

BOTANICA

GARDEN

2 ANNALS NEW YORK ACADEMY OF SCIENCES

in another species. In Batocrinus, the most frequent variation in the

radial series was due to the absence of the first costal, or rarely, to the

presence of an extra distichal below the axillary one. A greater amount

of variation occurs in the number of interbrachials, as these are simply

space fillers, and their number depends mainly on the relative height and

width of the cup. The most marked variation was found in the anal area,

Of the seventy-five specimens of Batocrinus studied, four had two plates

in the second row of the anal series, as in the Actinocrinide, and one of

twenty-five specimens of Cactocrinus had three plates in the second row,

after the manner of the Batocrinidew. As will be readily seen, this amount

of variation furnishes little evidence which can be used for working out

phylogeny, except in the most general way.

The ornament on the surface of closely related species differs in degree

rather than in kind, and hence does not show changes sufficiently definite

to furnish satisfactory results.

The stems of crinoids often show very definite and well-marked changes

from the proximal to the distal portion, but it is so comparatively rare to

find the crinoid stems intact for any considerable distance from the calyx

that they are only occasionally helpful.

A study of crinoid arms has shown that in some genera, at least, more

satisfactory results may be obtained. It has long been recognized that

the uniserial condition at the base of many arms which later become

biserial is reminiscent of ancestral species whose arms were uniserial

throughout. Applying the same principle to other characters, it is be-

lieved that changes in the form and ornament of the arm are indicatious

of changes through which the ancestors of a species have passed and that,

taken in connection with other characters, they may be used to determine

the phylogeny of the group to which the species belongs. This method of

study will obviously be most useful in genera having highly modified

arms, and the genus Cactocrinus has furnished the material upon which

the present paper is based. No single character can be used alone in

working out relationship, and in this study constant reference has been

made to the characters of the calyx as well as of the arms. The columns,

in nearly all the specimens available for study, were not preserved-

In the descriptions of species of Cactocrinus which follow, a reference

is given to the original description and to a later full description and fig-

ures. Only such facts are added here as have a bearing upon the present

investigation, except in the case of new species and Cactocrinus probosci-

dalis, which may be used as a standard of comparison for other species

and is fully described.

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY

eS)

DESCRIPTION OF CACTOCRINUS AND SIX SPECIES OF THE GENUS

Cactocrinus Wachsmuth and Springer

1897. Cactocrinus WacHSMUTH and Sprincer, North American Crinoidea

Camerata, p. 600.

The species included in the genus Cactocrinus were, with few excep-

tions, originally described under the genus Actinocrinus, and for the

present purpose, the genus is sufficiently defined by enumerating the fea-

tures by which it is distinguished from’ Actinocrinus. The most notice-

able of such distinguishing characters seems to be the arrangement of the

arms, which form a more or less continuous row around the calyx; that is,

the interbrachial and interambulacral plates do not meet between the

arms as is the case in Actinocrinus. Another distinguishing feature is

that, in species having more than four arms to the ray, the third bifurca-

tion takes place on the second or third plate above the distichals in Act-

nocrinus, while the axillary palmar immediately follows the axillary

distichal in Cactocrinus. The two genera are also said to differ in the

structure of the pinnules, but the spines on the proximal pinnules of

Cactocrinus are represented also on many species of Actinocrinus, as well

as on other genera as far removed as Dorycrinus and Hretmocrinus.

Hence this cannot be used as a distinctive feature.

The type of the genus is Cactocrinus proboscidalis (Hall).

Cactocrinus proboscidalis (Hall)

Plates plates hess 2 2a) 20

1858. Actinocrinus proboscidalis Hall, Rept. Geol. Sury. Iowa, Vol. 1, pt. 2,

p. 584, pl. 10, fig. 13.

1897. Cactocrinus proboscidalis Wachsmuth and Springer, North American

Crinoidea Camerata, p. 601, pl. 58, figs. 3, 4, 5, 6, 7 a—d.

The calyx of this species has a width slightly greater than its height.

There are, as usual in the genus, three basals, five radials and five each

of first and second costals. The axillary distichals rest directly upon the

second costals, and each of these gives rise to two arms, making four to

the ray. The surface of the calyx is ornamented by a node at the center

of each plate from which simple carine radiate across the margins and

become continuous with the carine from adjacent plates. The entire

surface of both cup and arms is covered with extremely fine granules.

The arms are long, three or four times the height of the calyx. Be-

yond the first palmars, from one to three plates pass entirely across the

diameter of the arm, hence the biserial condition is attained early in this

4 ANNALS NEW YORK ACADEMY OF SCIENCES

species. In form, the arms are cylindrical at the base, but at a distance

from the base varying from the third to the tenth plate, they become flat-

tened laterally, and the individual plates are elongated, producing a

marked expansion of the arm at about half its height which may be taken

to represent the adult stage. Beyond this, the arm tapers gradually to a

point, at the same time becoming more nearly circular in cross section

than at its middle portion. In the growth of the crinoid arm, new plates

are formed at the tip, and these small, nearly cylindrical plates are in an

immature condition. Their resemblance in form to the plates near the

base of the arm probably indicates that they are passing through a stage

comparable to an early stage in the development of the entire arm. That

such localized stages occur in other genera has already been pointed out

by Grabau.?

Immature plates were observed only in Cactocrinus proboscidalis and

C. baccatus. Others of the species studied had the arms strongly in-

curved and the tips concealed by the matrix, except in the C. multi-

brachiatus series where the arms were imperfect at the ends.

Kach plate of the arm of (. proboscidalis bears a distinct transverse

ridge running the entire width of the plate and situated about one-third

of its height from the upper margin. The ornament appears on early

plates, at distances from the base differing somewhat in different speci-

mens, and continues to the extreme tip of the arm. The proximal pin-

nules, as in other species of the genus, bear strong overlapping spines.

Column cylindrical. The proximal nodals project but slightly beyond

the internodals, but at a distance of about 20 millimeters from the calyx,

the nodals have twice the diameter of the internodals and have their

margins extended into a thin; knife-like edge. At a distance of 85 milli-

meters from the body, the number of intercalated plates has increased

until there are seven between successive nodals, and at this point the

nodals have blunt margins projecting but little beyond the internodals.

-'Tegmen moderately high, covered with numerous nodose plates. Anal

tube long and slender.

Horizon AND LOCALITY: Lower Burlington limestone, Burlington, Iowa. No.

415, Museum of Comparative Zodlogy collection.

Cactocrinus baccatus sp. nov.

Plate I, fig. 3; plate IT, figs. 3, 4, 4a, 4b

Calyx similar to that of Cactocrinus proboscidalis in form. Basals variable

in size, sometimes minute with the calyx resting upon the radials, sometimes

as large as in Cactocrinus proboscidalis.

7A. W. GraBau: Amer. Jour, Sci., 4th ser., Vol. 16, pp. 289-300. 1903.

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY 5

In arrangement of the plates and surface ornament, this species does not

differ essentially from C. proboscidalis, there being the usual number of plates,

five basals, five each of radials, first and second costals and ten axillary dis-

tichals each of which bears two arms, making four to the ray. The arms of

the two species are similar in form, being cylindrical at the base, strongly

flattened laterally throughout the greater portion of their length, tapering

and becoming more nearly cylindrical near the tips. The most characteristic

difference is in the ornament of the arms, for while the arm plates of C.

proboscidalis bear a single transverse ridge throughout, the arms of C. baccatus

have this simple ridge only near the base of the arm. At a distance from the

base varying from 6 to 20 millimeters in different specimens and varying to

some extent. in different arms of the same specimen, the transverse ridge is

broken up into a row of small nodes of which there are five or six on each

plate at the greatest diameter of the arm.

The column was not preserved with any of the specimens found.

HorizoN AND LOCALITY: Lower Burlington limestone, Burlington, Iowa. No.

558, Museum of Comparative Zoology collection.

Cactocrinus platybrachiatus, sp. nov.

Plate I, fig. 2; plate III, figs. 1, 2, 2a, 2b

The basals of the only specimen representing this species are not preserved:

Of the plates above the radials, only those of two rays and one interradial

area are preserved. Their arrangement seems to be the same as that usual in

the genus for five or six armed rays; that is, in one of the half-rays present,

the axillary distichal is followed, without intervening plates, by an axillary

palmar which gives rise to two arms. The palmar resting on the other axillary

face of the distichal bears one arm giving three arms to this half ray. The

same arrangement is seen in another half ray, but whether there were two or

three arms in the other half of the same ray cannot be determined. There is

one small interdistichal, and the formula for the interbrachials is 1, 2, 2, 1.

The ornament on the calyx is essentially the same as that of Cactocrinus

proboscidalis, but since there are more plates due to the greater number of

arms, and a ridge crosses each suture line between the plates, the cost ap-

pear more crowded than on the latter species. The node at the center of each

plate is also less prominent.

The arms are cylindrical near the base but expand rapidly in the median

portion. They are flattened laterally but less strongly so than the arms of

Cactocrinus baccatus. The form of the arms changes gradually, until in the

upper portion they are flattened dorso-ventrally. Their tips are incuryed

toward the anal tube and buried in the matrix. The bhiserial condition is at-

tained early, only one or two plates at the base passing entirely across the

arm. The surface of the arm is smooth at the base. A little later a transverse

ridge appears which soon breaks up into a row of nodes like those of Cacto-

crinus baccatus. This type of ornament persists for the greater portion of the

length of the arm, but by the time the dorso-ventral flattening is established,

some of the lateral nodes become confluent, reducing their number until there

are but three on each plate, and on some of the latest plates visible, there are

6 ANNALS NEW YORK ACADEMY OF SCIENCES

ouly two, a shorter node near the median line of the arm and an elongated

one placed laterally.

The column is unknown.

Horizon AND LOCALITY: Lower Burlington limestone, Purlington, lowa. No.

568, Museum of Comparative Zodlogy collection.

Cactocrinus platybrachiatus is distinguished from C. baccatus by the

greater number of arms, the dorso-ventral flattening of the arms and the

confluence of their surface nodes in the upper part of the arm, probably

representing a late stage of development. It is distinguished from C.

reticulatus by the many nodes on the arms at the maximum differentia-

tion in structure, representing the adult stage, the less strongly flattened

arms and the absence of lateral spines on the arms near their tips.

Cactocrinus reticulatus (Hall)

Plate III, figs. 3, 4, 4a, 4b, 4c

1861. Actinocrinus reticulatus Hall, Description of New Species of Crinoidea,

Preliminary notice, p. 2.

1897. Cactocrinus reticulatus Wachsmuth and Springer, North American

Crinoidea Camerata, p. 605, pl. 58, figs. 2a, 2b.

The arrangement of the calyx plates in this species is somewhat vari-

able, owing to the fact that it has sometimes five and sometimes six arms

to the ray. Of six specimens selected at random, three had 28 arms, one

27, one 24 and one 22 arms. When there are five arms to the ray, it is

always one of the median palmars which is axillary and bears two arms,

while with six arms to the ray, both median palmars become axillary and

the lateral palmars bear a single arm. On the calyx of large individuals,

the primary coste are sometimes bordered by a second series producing

a smaller triangle within a larger one. The nodes at the centers of the

plates are inconspicuous or sometimes absent.

In form, the arms are cylindrical at the base, but soon their plates are

elongated as in Cactocrinus proboscidalis (see Plate II, fig. 1). A little

later, the plates are curved, forming an arm equal in lateral and dorso-

ventral diameters. At a slightly higher point, the arms are flattened

dorso-ventrally, and the latest of the exposed plates are strongly flattened

in the same direction. ‘The ornament begins on the early plates of the

arm as a strong transverse ridge or elongate node near the lateral margin,

and a few plates later, a new node appears near the median line of the

arm. As growth continues, these two nodes appear on successive plates

nearer and nearer to the lateral margin, and when they have receded far

enough to leave a plain space near the median line, a new node appears in

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY q

that position. This node continues to increase in size at the same time

that the lateral node diminishes. Later, as the arm approaches its dorso-

ventrally flattened form, the lateral node disappears, the former median

node is elongated into a projecting spine and the newly introduced median

node is now a prominent feature of the ornament. The remainder of the

arm is incurved and buried in the matrix, hence the character of the

latest formed plates is unknown.

The column is not preserved on any of the specimens at hand.

Horizon AND LocaLity: Lower Burlington limestone, Burlington, Iowa. No.

527, Museum of Comparative Zodlogy collection.

Cactocrinus denticulatus Wachsmuth and Springer

Plate IV, figs. 1, la, 2, 2a, 2b

1897. Cactocrinus denticulatus Wachsmuth and Springer, North American

Crinoidea Camerata, p. 606, pl. 57, figs. 5a, 5b.

Cactocrinus denticulatus is closely related to C. reticulatus. The ar-

rangement of the calyx plates is the same, except that in C. denticulatus

six arms to the ray form a constant feature necessitating a greater num-

ber of plates for their support. The ornament is somewhat more elabo-

rate from the fact that small nodes are present on the coste of the upper

part of the calyx, and these sometimes extend as irregularly placed nodes

over the base of the arms.

The arms pass through the same series of changes in form as those

described for Cactocrinus reticulatus, except that the early condition with

elongate plates is not present, and the successive changes up to the dorso-

ventral flattening appear at a relatively earlier period in the development

of the arm than in the preceding species. The latest exposed plates of

the arm have a more extreme form than the corresponding plates of C.

reticulatus. ‘They are more strongly flattened dorso-ventrally, have longer

spines, and the nodes are so high and pointed that, in some specimens,

they might almost be called spines. Still further differences appear in

the lateral spines, which are often alternately longer and shorter, and

when this is the case, the nodes also alternate in size, the larger node

occupying the plate with the shorter spine. This alternation in size of the

spines and nodes is not perfectly regular, but it is a pronounced tendency

which manifests itself to some extent on all the specimens studied. The

nodes are not, as in the preceding species, close to the median line but

have receded to some distance from it.

The column is missing from all the specimens studied.

Horizon AND LOocALITY: Lower Burlington limestone, Burlington, Iowa. No.

534, Museum of Comparative Zodlogy collection.

8 ANNALS NEW YORK ACADEMY OF SCIENCES

Cactocrinus opusculus (TIlall)

Plate I, fig. 4; plate IV, figs. 3, 4, 4a, 4b, 4c, 4d

1860. Actinocrinus opusculus Hall, Suppl. Geol. Rept. Iowa, see description of

0) 48

1897. Cactocrinus opusculus Wachsmuth and Springer, North American Crinoi-

dea Camerata, p. 607, pl. 56, figs. 5a, 5b.

The calyx of this species bears a close resemblance to that of Cacto-

crinus reticulatus, except in the greater number of plates necessary for

the support of six arms to the ray, which is the normal number for C.

opusculus. The surface of the calyx is ornamented by a single node at

the center of each plate with connecting carine, as in C. reticulatus.

At the base, the arms are, as usual in the genus, cylindrical and smooth,

but they soon become flattened laterally, as in C. proboscidalis, and in

retarded specimens bear the strong transverse ridge on the arm plates

characteristic of that species. One specimen retains the C. proboscidalis

type of ornament for 25 or 30 plates, while in accelerated individuals this

condition is represented by only 2 or 3 plates, or may be absent altogether.

In average individuals, at a distance from the base varying from the

tenth to the twentieth plate, a slight angulation appears on the arm near

the median line. This slight elevation increases in size on succeeding

plates until it forms a distinct node. At the same time, it recedes far-

ther and farther from the median line. The lateral node continues to

increase in prominence until it becomes a distinct spine, and accompany-

ing this change in the node, and partly in consequence of it, the form of

the arm changes until it is strongly flattened dorso-ventrally. Mean-

while, another row of nodes has come in close to the median line on each

side, as in Cactocrinus reticulatus. At the highest point observable the

arm is strongly flattened dorso-ventrally with a row of spines along each

lateral margin and a row of nodes on each side of the median line.

From the time the angulation appears until it develops into a distinet

node, the surface of the plates is distinctly corrugated, although the

strength of the corrugation varies greatly in different specimens. The

specimen figured in Plate I, fig. 4, and Plate IV, fig. 3, is a highly accel-

erated individual showing all the characters at the acme of their develop-

ment.

HorIzoN AND LOCALITY: Lower Burlington limestone, Burlington, Iowa. No.

523, Museum of Comparative Zodlogy collection.

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY 9

COMPARISON OF THE PRECEDING SIX SPECIES

A study of the first five of the species just described shows a series of

gradations in structural characters which is here interpreted to mean that

they form a continuous phylogenetic series in which the tendency of

evolution has been from the simpler forms to the more complex.

Throughout ‘the comparisons which follow, changes in structural fea-

tures are assumed to represent stages in development, and the complete

series of such changes to express the evolution of the arm as a whole.

The calyces from Cactocrinus proboscidalis to C. denticulatus show a

progressive increase in the number of features to be considered. he

greater number of calyx plates is due to the increase in the number of

arms developed, from four in C. proboscidalis to six in C. denticulatus.

The elaboration of surface features is expressed in additional carinze and

fine nodes covering them in C. denticulatus.

The arms furnish more conclusive evidence of relationship. In study-

ing the arms of crinoids, we have to consider several distinct characters,

such as the stage at which the biserial condition is introduced, the form

of the arm as expressed in its transverse section, the thickness of the in-

dividual plates and the surface features or ornament of the arms. Each

of these characters may develop at a different rate of evolution in differ-

ent specimens or even in different arms of the same specimen, but in the

same phyletic series new features for each will appear in the same order

but not, as already stated, necessarily at the same time. For example, we

may find in one arm of Cactocrinus denticulatus the median row of nodes

well developed on the twenty-fifth plate, while in another arm they are

not distinct until the thirty-fifth. The lateral row of nodes may be de-

veloped on the sixth plate or not until the fifteenth plate, but the median

row never appears before the lateral row.

Comparing the arms of the five species in detail, we find that Cacto-

crinus proboscidalis has a laterally flattened arm with simple transverse

ridge. (C. baccatus retains the same form and, according to the interpre-

tation of the facts here given, passes through the same early stages as its

ancestor, C. proboscidalis ; that is, first cylindrical, then laterally flattened

with a transverse ridge on each plate, but this species goes a step farther

in the breaking up of the transverse ridge into a row of nodes. In both

these species, the arms taper to a point. The arms of CO. platybrachiatus

pass through the same early stages as its ancestors, repeating the trans-

verse ridged stage of C. proboscidalis, the nodose stage of C. baccatus and

adding a feature of its own in the confluence of the nodes at a late stage of

development. In form, the arms present entirely new features in their

10 ANNALS NEW YORK ACADEMY OF SCIENCES

expansion near the point of curvature and their dorso-ventral flattening.

In the arms of C. reticulatus, the stage of the cylindrical smooth arm is

followed by one in which each plate bears a short prominent ridge near the

lateral margin which is believed to represent the confluent nodes of its an-

cestor, now reduced to one elongate node, or short ridge, placed close to the

lateral edge of the plate. A few plates later,a small node appears near the

median line. This stage is represented on Plate ITT, fig. 3. In successive

plates of the arm, these two nodes appear nearer and nearer to the lateral

margin until a plain space is left into which a new row of nodes is intro-

duced near the median line. The median nodes increase in strength, while

the outer ones diminish in size as they recede toward the lateral margin

until they disappear. Meanwhile, the form of the arm has changed, be-

coming flattened dorso-ventrally so that the former median node occupies

the lateral margin and is elongated into a spine. The line of nodes of

latest origin remains near the median line. These changes are illustrated

on Plate III, figs. 3,4, 4a-4c. It thus appears that, in this group at least,

new features arise near the median line of the arm and on successive

plates seem to move laterally until they disappear and are replaced by

features of later origin. This fact has led to the conclusion, stated above,

that the elongate node on early plates of Cactocrinus reticulatus repre-

sents confluent nodes in a late stage of their evolution and soon to disap-

pear, rather than that it has any relation to the transverse ridge present in

varly stages of its predecessor, C. platybrachiatus. The smooth space thus

left on the median half of the plate, in the preceding species, becomes a

field for the introduction of new features which appear successively as

lines of nodes.

In the arm of C. denticulatus, the earliest stage to appear is that with

an elongate node and a shorter one, both near the lateral margin of the

plate. ‘The ancestral features are, in this species, somewhat obscured by

the presence, on early plates, of nodes which are the continuation over

the base of the arms of the irregularly placed nodes present on the calyx

of this species. They constitute a feature of later origin quite distinet

from the two nodes near the lateral margin of thé arm plates. These

irregularly placed nodes are present only on early plates of the arm, and

by the time the eighth plate is reached, they have disappeared, as shown

on Plate IV, fig. 1. The two nodes remaining after the disappearance of

the irregularly placed nodes are, in the specimen figured, sharply pointed,

but this is not a constant feature for the species. Beyond this point, the

evolution of the arm for the greater portion of its length is the same as

that described for C. reticulatus, except that it is more accelerated, new

features appearing at an earlier period than in the latter species. The

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY 11

final stage in the evolution of the arm of C. denticulatus is more extreme

than that of C. reticulatus in that the arms are more strongly flattened,

the spines are longer and there is an alternation in the size of both spines

and nodes. The lateral movement of surface features is further illus-

trated in this species by the fact that on the latest plates observable, the

line of nodes last introduced does not remain near the median line as on

Q. reticulatus but has receded to some distance from it.

This series of five species of crinoids appears to constitute an excellent

illustration of the principle of recapitulation, each member repeating the

life history of its ancestor until, in the later members, early stages are

crowded out of the ontogeny to be replaced by characters of later origin.

Cactocrinus opusculus, the sixth of the species described above, bears

a strong general resemblance to C. reticulatus, but it has always six arms

to the ray and consequently more plates in the calyx. The arms at the

latest stage observable are closely similar to those of C. reticulatus at the

same stage, but they have arrived at this condition along a different path

from that traversed by the latter species, as shown by a comparison of the

figures on Plate IV, fig. 3, with those on Plate ITI, fig. 3. The early stages

lack the strong lateral node seen on C. reticulatus, and there is no indica-

tion in the ontogeny of the species that it has passed through the stage

with rows of nodes present on C. baccatus and C. platybrachiatus. C.

opusculus seems to have been descended from C. proboscidalis but as a

lateral branch, following a different line of evolution from that of the

C. reticulatus series. The resemblance between the final stages in the

arms of C. opusculus and C. reticulatus may be considered a case of

parallelism.

Another line of evolution from C. proboscidalis, divergent from that

of the reticulatus series, is represented by C. clarus. This species closely

resembles C. proboscidalis in the calyx and in the strong lateral flatten-

ing of the arms, but it is a much larger species and has five or six arms

to the ray. The arms have on their early plates a transverse ridge which

is strong near the lateral margin and is faint or absent near the median

line. On successive plates this ridge becomes shorter and shorter, 1. e.,

apparently moves laterally on the arm like the nodes of C. reticulatus

until, between the thirtieth and fiftieth plates, it disappears altogether,

and the arm plates are smooth. These facts are here interpreted to mean

that C. clarus is descended from C. proboscidalis but diverges from other

lines of descent in the direction of loss of the ornamental feature repre-

sented by the transverse ridge.

Having followed certain lines of descent from Cactocrinus probosci-

dalis, it would be interesting to trace its ancestry, but I have, as yet, seen

12 ANNALS NEW YORK ACADEMY OF SCIENCES

no specimen which seems to fulfil all the requirements for such an an-

cestor. We may, however, reasonably infer what were some of its char-

acteristics. The arrangement of the calyx plates was probably the same

as that of C. proboscidalis, and the plates were nodose, either with or

without connecting carine. The arms were cylindrical, smooth, tapering

at the tips and the biserial condition was attained late, 7. e., more than

two or three plates passed entirely across the diameter of the arm. Such

an ancestor would be expected to occur in strata older than those con-

taining C. proboscidalis, and we should naturally look for it in the Kin-

derhook, but the species of Cactocrinus recorded from the Kinderhook,

C. nodobrachiatus, C. ornatissimus and C. arnoldi, have ornamented

arms of a type quite different from those of C. proboscidalis or any of its

descendants. This indicates that the ancestor of Cactocrinus must have

lived at a period considerably earlier than the Kinderhook.

Cactocrinus thetis, of the Lower Burlington, has arms which in form

and surface are like those of the hypothetical ancestor of C. proboscidalis,

but they are biserial almost from their point of origin, and there are six

arms to the ray, while C. proboscidalis has but four. C. thetis was prob-

ably descended from the same ancestor as C. proboscidalis, but while the

latter has developed in the direction of surface ornament and modifica-

tion in the form of the arms, (. thetis has been retarded in surface orna-

ment and has advanced in the direction of number of arms and in the

early attainment of the biserial condition. The two species represent

divergent lines of evolution.

Another species of Cactocrinus which probably occupies a relation to

C. proboscidalis similar to that of C. thetis is C. thalia. The latter spe-

cies has long, slender, cylindrical, smooth arms, only four to the ray, but

it does not seem to be an ancestor of C. proboscidalis, since it is a larger

species with longer and more slender arms which become biserial at an

early stage.

CACTOCRINUS MULTIBRACHIATUS SERIES

Cactocrinus multibrachiatus (Hall)

1858. Actinocrinus multibrachiatus Hall, Rept. Geol. Sury. Iowa, p. 580, pl. 10,

fig. 10.

1897. Cactocrinus multibrachiatus Wachsmuth and Springer, North American

Crinoidea Camerata, p. 617, pl. 56, figs. 6, 7; pl. 58, fig. 8.

The calyx of this species resembles that of C. proboscidalis except in

the greater number of plates necessary for the support of eight arms to

the ray, this being the normal number for the species, although a smaller

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY aR

number is frequently present. The post-palmars, palmars and axillary

distichals rest one upon another without intervening plates, following the

usual plan in the genus Cactocrinus. ‘The nodes at the centers of the

plates are not prominent, and the costw are simple, except on the lower

half of the radials, where there are sometimes two or three passing to the

basals.

The arms are long and slender, tapering very gradually to the tips and

but slightly incurved. They are cylindrical for a distance of about twenty

to thirty plates from the base and then become somewhat flattened dorso-

ventrally, developing an obtuse angulation along the lateral margin. At

about half their length, the arms are somewhat expanded laterally, and

at this point or a little higher, they develop a narrow transverse ridge

close to the upper margin of each plate. These ridges give the arm an

appearance of being serrated along its lateral margin with each plate

slightly inset above its predecessor. The arm of C. multibrachiatus is

well represented by the figures of C. cwlatus spinotentaculus on Plate V,

fig. 1, except that it is all on a smaller scale.

HORIZON AND LOCALITY: Lower Burlington, Burlington, Iowa. No. 548, Mu-

seum of Comparative Zodlogy collection.

Cactocrinus ceelatus var. spinotentaculus (Hall)

Plate V,. figs: 1, 2, 2a

1860. Actinocrinus spinotentaculus Hall, Suppl. Geol. Rept. Iowa, .p. 86.

1897. Cactocrinus caelatus var. spinotentaculus Wachsmuth and Springer, North

American Crinoidea Camerata, p. 619, pl. 59, fig. 10.

This species is closely similar to the preceding, except that it is much

larger and the calyx is proportionally higher. The proportion of height

to width in C. cwlatus var. spinotentaculus is about 1: 1'/, as compared

with 1: 114 in C. multibrachiatus.

In arrangement of plates and surface ornament, the two species are

the same. The arms are eight to the ray and so similar to those of C.

multibrachiatus that the same drawing serves to represent the character-

istics of both, keeping in mind the fact that the present species is more

than twice the size of C. multibrachiatus, and the corrugations of the

surface, in common with other features, are much coarser.

Hor1IzoN AND LOCALITY : Lower Burlington, Burlington, Iowa. No. 552, Mu-

seum of Comparative Zodlogy collection. ;

14. ANNALS NEW YORK ACADEMY OF SOIENCES

Cactocrinus limabrachiatus (Hal!)

Plate V, figs. 3, 4, 4a, 4b

1861. Actinocrinus limabrachiatus Hall, Description of New Species of Crinoi-

dea, Preliminary notice, p. 2.

1897. Cactocrinus limabrachiatus Wachsmuth and Springer, North American

Crinoidea Camerata, p. 608, pl. 58, figs. 9, 10a, 10b.

The arrangement of plates in the calyx of this species is the same as

that already described for species having six arms to the ray. The sur-

face is highly ornamented with strong nodes and carine, which, on the

larger calyces, are of two series. The carine leading to the arms are

much stronger than the others. |

The arms of each ray are grouped together, suggesting the arrange-

ment in Actinocrinus, although the spaces between the rays are still nar-

row. ‘The arms are long and slender, cylindrical at the base, but they

soon become flattened dorso-ventrally. They are slightly expanded at a

distance of about half their length from the base and taper very gradually

to the tips. The biserial condition is reached late in the development of

the arm, there being from four to seven plates at the base which pass

entirely across its diameter. At a distance of from 5 to 8 millimeters

from the base, varying on different arms, each plate is ornamented by a

projecting transverse ridge near its upper margin, and the surface is coy-

ered by strong vertical corrugations. This type of ornament persists to

the tip of the arm, while its form changes from cylindrical at the base to

strongly flattened above, as shown by the transverse sections, Plate V,

figs. 4, 4a, 4b.

HorizoN AND LocALITY: Lower Burlington, Burlington, Iowa. No. 528, Mu-

seum of Comparative Zodlogy collection.

COMPARISON OF THE PRECEDING THREE SPECIES

A comparison of Cactocrinus multibrachiatus and C. celatus var.

spinotentaculus shows the relationship between the two to be so close that

they might be considered the same species, were it not that in a large

series of specimens, C. multibrachiatus shows all the characters of an

adult individual, while it is only about half the size of C. cwlatus var.

spinotentaculus.. The proportionally much higher calyx of the latter is

also a distinctive feature. The arms of the two species pass through the

same structural changes, which are interpreted as stages of development

and are closely similar, except that in C. ca@latus var. spinotentaculus,

they are biserial nearer the base and are larger.

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY 15

It seems reasonable to assume that C. cwlatus var. spinotentaculus is a

direct descendant from C. multibrachiatus, differing but little from the

latter, its immediate ancestor. I have not seen the arms of Cactocrinus

celatus,; hence comparisons are made with its variety, of which well-pre-

served material is available.

Cactocrinus limabrachiatus resembles C. multibrachiatus in the form

of the calyx and in the changes in form through which the arms pass.

The ornament on the surface of the calyx and the arms of the former

species is similar in kind to that of the latter, but is more extreme, the

cost being stronger and more numerous and the corrugations of the

arms coarser. In this respect, it is more highly differentiated than C.

multibrachiatus, but in the number of arms and in the late attainment

of the biserial condition it is more primitive. My interpretation of these

facts would be that both are descended from a common ancestor but rep-

resent divergent lines of evolution, Cactocrinus limabrachiatus having

developed in the direction of a high degree of surface ornament, while

C. multibrachiatus has advanced in number of arms and earlier develop-

ment of biserial plates.

RELATION OF CACTOCRINUS TO T'ELEIOCRINUS

The derivation of the genus Teleiocrinus from Cactocrinus has already

been suggested by Wachsmuth and Springer,’ and it is interesting to note

that the development of the arms confirms the evidence derived from the

calyx and the mode of branching of the arms.

In Teleiocrinus umbrosus (Hall), the type of the genus, the arms are

more numerous and more slender than those of Cactocrinus celatus var.

spinotentaculus. Their slenderness is perhaps due to their greater num-

ber, both on account of economy of material and the crowding due to fre-

quent branching near the base. The method of branching in T'eleiocrinus

follows the Cactocrinus plan, each axillary being succeeded by another

without intervening plates of the same order until there are fifteen or

sixteen arms to the ray. In form, the arms are cylindrical at the base, or

in accelerated individuals somewhat flattened even at this point. Higher

up on the arms, they become strongly flattened dorso-ventrally and de-

velop a narrow transverse ridge near their upper margins. The corruga-

tions on the surface of the arms are much finer than those of Cactocrinus

celatus var. spinotentaculus, as might be expected from the more delicate

structure of the whole arm. The arm of Teleiocrinus umbrosus is figured

on Plate V, figs. 5, 5a. A comparison of these figures with those of

3 WACHSMUTH and SprinGer: North American Crinoidea Camerata, p. 627. Cam-

bridge, 1897.

16 ANNALS NEW YORK ACADEMY OF SCIENCES

Cactocrinus calatus var. spinotentaculus on the same plate shows the

close similarity between the arms of the two species throughout their

entire development. T'eleiocrinus umbrosus seems to have been developed

from Cactocrinus cvlatus var. spinotentaculus by an increase in the size

and thickness of the calyx plates and a more frequent branching of the

arms near their base, which produced the expanded rim of the calyx char-

acteristic of Teleiocrinus.

Telerocrimus wiabrosys

G& coclatus ;

: SPIMOECTILEOC UTS

C denticu/atius ie

C opusculus Creticulatus

| C wrultibrachiotus

Ss platybra chralts

| C. Ninabrachia-

C. thetys C haccatus Pele

| C. clarus

G: prohoscidalis -

Cthalva

ae)

ma)

Smooth arvim7ed anceslor

Fic. 1.—Relationship of species of Cactocrinus and Teleioerinus

Televocrinus altha@a (Hall) is represented in the collection of the Mu-

seum of Comparative Zodlogy by only one specimen which preserves the

arms. From this, it appears that the numerous arms are flattened dorso-

ventrally at the base but become larger and cylindrical in form above.

This suggests that we have in Teleiocrinus althea an actual advance in

evolution expressed in a simplification of form rather than in greater

poe

The general relations of the species mentioned above are expressed in

diagrammatic form in Fig. 1.

WOOD, CRINOID ARMS IN STUDIES OF PHYLOGENY 17

CONCLUSION

The considerations presented in the above paper constitute only a be-

ginning in a line of investigation which seems to promise good results, if

followed out in genera which have highly modified arms. From the

proximal to the distal portion of the arm, we find a series of changes in

structural features which succeed one another in a definite order. These

changes may be interpreted as stages in development, each individual re-

peating the stages present in its immediate ancestor and adding, in the

distal portion, new characters of its own until the number of characters

becomes too great for representation in the life history of a single organ-

ism, and certain characters, usually the earlier ones, are greatly abbre-

viated or are omitted from the ontogeny of highly modified descendants.

When thus interpreted, the arms of crinoids furnish evidence from which

the phylogenetic relations of different species and genera can be inferred.

With the attention once drawn to the subject, it will probably be found

that the number of genera which may be studied by this method and the

degree of modification existing are greater than would appear at first

thought.

PLATE

XXIV,

= RR

Ot a NALD RS Sim,

6888 eer pen

on ea sa

VOLUME

SOL.

ACAD.

ANNALS N. Y.

| Poy

Pe peor”

teers

ane

ees

» WOT iting, +

amy

wet J

ae” ;

as SS

tanlf

E. ROWE

FROM PHOTOGRAPHS BY

BOSTON

HELIOTYPE CO.,

ANNALS N. Y. Acan. Scr. VoLuME XXIV, PLATE II

Bo @ * )*

2b a 4b

ELVIRA WOOD, DEL.

ANNALS N. Y¥. ACAD. SCI. VoLumeE XXIV, PrareE III

ELVIRA WOOD, DEL.

ANNALS N. Y. Acap. Sci.

ELVIRA WOOD, DEL.

Votume XXIV, PLATE IV

VOLUME XXIV, “PLATE V

INGAD. OCI.

ANNALS N.

ELVIRA WOOD, DEL.

’

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Pas eee et! a

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_ ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIV, pp. 19-22

Editor, Epmunp Otis Hovey

NOTES ON CAMARASAURUS COPE

aise 818g

: C. C. Moox

“~ NEW YORK

PUBLISHED BY THE ACADEMY

®1 May, 1914 ,

THE NEW YORK ACADEMY OF SCIENCES

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OFFICERS, 1914 <

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[ANNALS N. Y. Acap. Scr., Vol. XXIV, pp. 19-22. 21 May, 1914]

NOTES ON CAMARASAURUS COPE

By C. C. Moox

(Read before the Academy, 9 March, 1914)

CONTENTS

Page

Origin ve dESCLIp MOM eters erasers a oelostereievoletei ereleloieve oleisle ee sree svsials ayers lel eve 19

IEG HONS TES 5 Soe ob Ob OOO COI DID REE ODO b.ceNe Eoin OIG oI cO CO CICS Oran ares 21

COPE SMECSLOLAIGLOMAv st ntevotare che eh ottrstencreceicco) ober nicte ay ole syeneloley dccsve ei ivdiele/enatar eis dtele cts 22

ORIGINAL DESCRIPTION

Camarasaurus was originally described by Edward D. Cope in “‘Pale-

ontological Bulletin 25,” published August 23, 1877. The type species

is Camarasaurus supremus, and the type specimen consists of a cervical,

three dorsal and four caudal vertebre. ‘These bones were found near

Canyon City, Colorado, and in the same quarry a considerable number

of bones were excavated, belonging to three or more individuals. These

bones were more or less associated with the type and it is impossible to

say which belongs to one individual and which to another. The vertebre

of the original type may not all belong to the same individual. The

various remains are of the same general character and there need be no

hesitation in referring them to the same genus and species. Some of

these later bones were described in a subsequent paper in the American

Naturalist for February, 1878, and figures of vertebra, scapula and pubis

were given. All of these remains together now constitute numbers 5760,

5760’, 5761, 5761’, 5761”, 5761a, of the collections of the American Mu-

seum of Natural History.

The original description by Cope confounds to some extent the generic

characters of Camarasaurus with the characters of the Sauropoda as a

whole. The hollow centra, and lightly built, laminated neural arches and

spines are possessed by all the Sauropoda, some members of the group

possessing the lightening structures to a much greater degree than does

Camarasaurus.

The general characters of Camarasaurus, without giving detailed de-

scriptions, are as follows:

Cervicals: Number probably thirteen, of moderate length, of considerable

height, with spines double, without a median tubercle.

(19)

20 ANNALS NEW YORK ACADEMY OF SCIENCES

Dorsals: In the restoration made by Cope the number of dorsals was placed

at twenty. Later the series was studied at the American Museum, and a com-

posite column was made up by placing together vertebrie showing progressive

fore-and-aft characters. At this time the number was estimated to be four-

teen, of which thirteen were actually represented, dorsal two being absent. In

the fall of 1913, opportunity was given the present writer by Professor Henry

Fairfield Osborn to restudy these vertebrie in preparation for his monograph

on the Sauropoda. It was then found that by the elimination of duplicate

bones the number is probably ten.

RELATIONSHIPS

The close similarity of Camarasaurus with Morosaurus has long been

considered ground for placing the two genera in the same family. At

the present time, it appears that this similarity is close enough to force

the conclusion that the two animals belong to the same genus. Among the

characters common to Camarasaurus and Morosaurus, the following may

be mentioned :

1. Centra of dorsals increasing gradually in opisthocelianism from the

posterior to the anterior region.

2. Principal laminze supporting the transverse processes strong, with little

development of accessory lamin.

3. Spines low and broad, with only one cavity of any importance on their

sides.

4. Caudals short, with inferior surfaces of centra convex in transverse

direction.

5. Scapulie short, greatly expanded at both proximal and distal ends.

6. Humerus short and stout, index of maximum length into minimum cir-

cumference about .440.

7. Ulna slightly twisted at the distal end.

8. Femur very stout, index about .440. Ratio of length of femur to length

of humerus about .600.

9. Metacarpals long and slender.

10. Sacral spines low and broad.

11. Ischium slender, tapering distally.

The only characters in which the two forms differ are those which may

be taken as individual variations or specific characters, such as size, posi-

tion of capitular rib facets on anterior dorsals, presence or absence of a

median tubercle between the two spines of the anterior vertebre, or slight

differences in the laminar supports of the transverse processes.

It is concluded, therefore, that Camarasaurus and Morosaurus are

generically identical, and as Camarasaurus has a priority of about one

month, the species now under Morosaurus should be referred to the

former genus.

MOOK, NOTES ON CAMARASAURUS COPE

About 1/100 natural size

Restoration of Camarasaurus by Cope.

FIGuRE 1.

The position of the fore limb in relation to the vertebral column was not indicated by Cope

De ANNALS NEW YORK ACADEMY OF SCIENCES

Corr’s RESTORATION

A life-size restoration of Camarasaurus was made by Dr. John A.

Ryder under the direction of Professor Cope about 1878, parts of several

individuals being assembled to make a composite individual.

The material on which the restoration of the skull was based was very

incomplete, only the posterior portion of the cranium and the anterior

portion of the mandibles being represented. The restoration of the skull

was, therefore, almost entirely hypothetical. The teeth were restored as

of carnivorous rather than herbivorous type, and were placed along the

sides of the jaws instead of in the front as is now known to be the case in

the Sauropoda. The teeth extend posteriorly behind the orbit, some of

them even appearing to be rooted in the jugal bone.

The cervical and dorsal vertebrae are not distinctly separated in the

restoration, nor are the dorsal and sacral. No ribs are represented. The

cervical series as restored contains ten or twelve vertebre, no atlas being

represented. The dorsal series contains sixteen, seventeen or nineteen

vertebre, according to the interpretation of vertebra eleven and twelve as

dorsals or cervicals, and vertebra twenty-nine as dorsal or sacral. Sixty

caudals are present in the restoration. According to our present knowl-

edge of Camarasaurus, the number of cervicals should be twelve or thir-

teen, the number of dorsals ten, of sacrals five, while the number of cau-

dals is doubtful. In the restoration, there are too many anterior caudals

and too few small distal ones.

The bones of the fore-limb are too long in the restoration. Four hypo-

thetical carpal bones are represented. The phalangeal formula of the

restoration is 4, 5, 5, 5, 5. The ischium is represented as slightly ex-

panded at the distal end as in Brontosaurus, instead of tapering slightly

as it does in the type. The tibia and fibula are each about seven inches

longer than the actual bones. Three tarsal bones, of which at least one

is hypothetical, are represented. The phalangeal formula as restored is

%, 3, 35 5, 4.

It is interesting to observe that, at this early date, Professor Cope con-

cluded that the Sauropoda walked upright, instead of crawling, as was

contended a few years ago by Tornier and others, and denied by Matthew

and Holland.

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ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIV, pp. 23-38, pl. VI

Editor, Epmunp Otis Hovey

THE GENESIS OF ANTIGORITE AND TALC

ALEXIS A. JULIEN

NEW YORK

PUBLISHED BY THE ACADEMY

25 JuLy, 1914

THE NEW YORK ACADEMY OF SCIENCES

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[Annas N. Y. AcaAp. Sci., Vol. XXIV, pp. 23-38, Pl. VI. 25 July, 1914]

THE GENESIS OF ANTIGORITE AND TALC

By Auexis A. JULIEN

(Presented by title before the Academy, 7 April, 1914)

CONTENTS

Page

THAR TONE gigs ao ooo maed b9.5 Or 18s GG COBO BO BOO Od CORD. OD DD ICO OIO. 23

TMG GAIT OF Talked oencadesadeahasee saatoe Go capo Gidmy > que BP Sites MRE 25

TAS CENA Oe MiMniTEs 6 aa6go00do co vOdoS MONO OoboOo Go COO UG EU oO lao 26

Formation of antigorite from olivine by hydration.................. 26

Formation of antigorite directly from olivine by thermal alteration... 28

Direct hydration by agencies between two belts...............+-.04- 29

Dual processes in genesis of tale and antigorite........................- 30

Genesis of chrysotile and retinalite........................ Fit RNR Scr 33

WOM POSTUCMVEITSE ele tress tcl srehalsia ors) aie otere oie ro fat ctailokavioucrs shatacehe elo: oteis elei tel 'elig, vcyere he 36

COGiVGIENGIIES Sta aa Shao cote Malte «cod coer ROice no hCrca CEE ete tence eee eee 38

INTRODUCTION

The avowal of Delesse in 1865—“Above all other eruptive rocks, ser-

pentine has hitherto remained a veritable enigma !”—still pertains to all

prevalent hypotheses concerning its origin. Although indeed the existence

of a “serpentine group,” as complex as Schweizer’s series (picrosmine,

picrophyll, substance e, antigorite, serpentine, chrysotile and other sub-

stances a, b, c, d, f) is no longer in common acceptance, there are few

mineralogical authorities even now who are not inclined to favor at least

the dual distinction, “serpentine” and chrysotile, with differentiation as

allomorphs in physical and optical characteristics if not in chemical com-

position. The solution appears to have been long delayed by ignorance

of certain facts:

1). The impurity of specimens.—The term “serpentine” has been

indifferently applied to all forms of the mineral, and, with the same

freedom, to the massive rock, often designated as “ordinary serpentine,”

in which the proportion of the mineral rarely exceeds 60 to 80 per cent.

and may even fall to 35 per cent. or less. In opposition to this loose

practice, Lacroix has long ago urged the restriction of the term “antigo-

rite” to all forms of the mineral proper, and of the term “serpentine”

exclusively to the rock occurrences. Analogy with the precision obtained

by discrimination of calcite from limestone, of dolomite (or miemite, ac-

(23)

a4 ANNALS NEW YORK ACADEMY OF SCIENCES

cording to some) from magnesian limestone, of tale from steatite, etc.,

confirms the advantage of such distinctive use of the two terms, if antigo-

rite as a definite mineral shall be held to comprise all substances of the

contposition H,Mg,Si,0,.

In most of its specimens, however careful their selection for apparent

purity, as judged by uniform texture, color and translucency, such as

“noble serpentine,” retinalite, etc., the evidences of large intermixture

with other substances are readily established. As this impurity mainly

consists of other magnesian salts, the usual method of identification of

antigorite by deduction of certain molecular ratios from the analysis is

by far too rude and unreliable. Only by recasting of the analysis,’ with

precise reference to the percentage of combined. water and, if possible,

with control by microscopic and optical examination of the very material

used for the analysis, can the true constitution be determined for the

aggregate present in almost every specimen of the presumably pure min-

eral. An unfortunate consequence of disregard of these precautions has

been the partial vitiation of many physical and chemical investigations

of the mineral. For example, it is easily determined, by recasting of the

stated analyses, that specimens of the “dark green serpentine” from

Newburyport, Massachusetts, selected as typical in experiments for de-

termination of constitutional formula,? actually contained 11 to 22 per

cent. of deweylite, etc.; and that the foliated antigorite from Antigorio,

Piedmont, used for determination of the form of silicic hydrate existing

in the constitution of true antigorite,’ contained 15 per cent. of prochlo-

rite, deweylite, ete. It may be fairly suspected that this impurity of

material may have led in part to uncertainty attending conceptions of

that constitution.

In regard to tale, its ordinary intermixture with quartz, chlorite, antig-

orite, tremolite, ete., is well known.

2). The obscurity of the products of decay in laterite——In past dis-

cussions, the grains of antigorite and scales of shining tale detected on

weathered outcrops, though merely ancient elements residual from their

insolubility, have been commonly mistaken for new generations. This

misleading presumption has hindered recognition of the actual abundant

derivatives from rock decay, magnesia, its hydrate, carbonates and soluble

hydrosilicates. The resulting discordance of inferences from the numer-

ous proposed genetic hypotheses for tale and antigorite, with facts even

1 Ann. N. Y. Acad. Sci., XVIII, 129-146. 1908.

2? CLARKE AND SCHNEIDER: Am. Jour. Sci. (3), XL, 308. 1890.

3S. HILLEBRAND: Sitz.-ber. d. math.-naturw. Kl. d. r. Acad. d. Wiss., Berlin, CXV,

Abt. I, 697-712. 1906.

JULIEN, GENESIS OF ANTIGORITE AND TALC 2}

then known concerning the products of weathering of ferro-magnesian

minerals and rocks, may be briefly reviewed in connection with each

mineral.

THe GENESIS OF TALC

In regard to tale, T. S. Hunt* in 1860 made the following suggestion,

without further elaboration:

“While steatite has been derived from a compound like sepiolite, the source

of serpentine was to be sought in another silicate richer in magnesia.”

In this, his conjecture concerning tale was a happy one and was ap-

proved by Delesse in 1861. By neither was there ever advanced any

explanation or proof and the fleeting suggestion dropped from view.

Taking for example a single mineral, olivine, as the source of talc, as

in the peridosteatites of Maryland and North Carolina, the following

genetic equation, for direct alteration of olivine into tale, has been pro-

posed :°

4(Mg, Fe), Si0,—5(Fe, Mz)O+H,O=H,Mg,(Si0,),

Olivine Iron oxide and Tale

magnesia

So also the derivation of tale from tremolite or enstatite has been at-

tributed to attack by carbonated waters, as explained by the reactions®

CaMg;Si,O,. + H,0 + CO,= H,Mg,Si,0,, + CaCO,

Tremolite Tale Calcite

Mg,Si,O,. + H,0 + CO, = H,Mg,Si,0,, + MgCO,

Enstatite Tale Magnesite

According to another authority :7

“Tale forms in the upper zone of metamorphism. In this respect it is like

ehlorite and serpentine. It is especially likely to form under conditions of

weathering. . . . It appears to be one of the end products of rock alteration

in the belt of weathering.”

Yet in the decay of olivine, for example, on weathered outcrops of

dunite or other peridotite, while there can be no doubt of the removal

of iron oxide and magnesia and of absorption of water, not a trace of

newly formed tale has ever been distinguished among the products of

decay. Furthermore, the above equations take no note of the free silica

which has universally separated in abundance during development of

*+Chem. and Geol. Essays, Boston, 296. 1875.

5 J. H. PRATT AND J. V. Lewis: N. C. Geol. Survey, I. 1905.

°C. H. SmytH, Jr.: Sch. of Mines Quart., XVII, 333. 1896.

7™C. R. VAN Hisp: Treatise on Metamorphism, U. S. Geol. Sury. Monogr. 351. Wash-

ington, 1904. :

26 ANNALS NEW YORK ACADEMY OF SCIENCES

tale and has become either a prominent constituent of the resulting

quartz-talc aggregate, steatite, or a prominent associate in veins or seams

in close vicinity to a tale-rock.

THE GENESIS OF ANTIGORITE

For the purpose of this paper it will be unnecessary to discuss all the

hypotheses which have been devised, or to consider but one important

source, olivine. <A review of the literature reveals, in my opinion, pro-

gressive but still imperfect recognition of the nature and conditions of

the genesis of antigorite, and, on the other hand, a growing consciousness

of the insufficiency of the tentative speculations concerning its location.

These comprise three methods of change of olivine directly into antig-

orite, viz: by weathering, by attack of deep-seated agencies and by com-

bination of both.

FORMATION OF ANTIGORITE DIRECTLY FROM OLIVINE BY HYDRATION

The hydration which antigorite represents toward olivine as the mother-

mineral, the visible evidences of its production by attack from the out-

side upon the olivine grains, the attending oxidation of ferrous iron, the

removal of certain bases and the release of free silica are obvious results

of the decay by weathering. What conclusion more simple and plausible

than that antigorite has been mainly produced in such instances by direct

hydration of olivine?

An early writer (J. Roth,* 1869), although he had distinguished vari-

ous processes of weathering as simple and complex, discussed antigoriza-

tion under the former heading, thus.

(10 MgO-+5 Si0,)—(4 MgO + SiO,) +4 H,O—(6 MgO +4 SiO, +4 H,0)

5 molecules olivine 2 molecules “serpentine”

J. J. H. Teal® (1888) was content to declare:

“The alteration of olivine by surface agencies—water, carbonic acid and

oxygen—gives rise to serpentines and other pseudomorphs ;”

and

“the formation of serpentine by the. alteration and hydration of ferro-magne-

sian and magnesian silicates is proved beyond all question,” 1

with the equation:

“2 (2 MgO +SiO,) —MgO + 2 H,O=(3 Mg0+2 SiO, + 2 H,O)”

Forsterite “Serpentine”

8 Abh. d. k.-Akad. d. Wiss. Berlin, 1869.

® British Petrography, 104-106. London, 1888.

JULIEN, GENESIS OF ANTIGORITE AND TALC Q”

According to a view now in common acceptation,’°

“the conception of G. P. Merrill, that ‘the formation of serpentine as a rock is

a deep-seated process,’ however, does not preclude the generation of dissemi-

nated serpentine, regarded not as a rock but as a mineral species, within the

belt of weathering. . . . The probable reaction is as follows:

2 Mg,SiO,+ 2 H,O+ CO,=Mg;H,Si,O, + MgCO,”

Olivine Serpentine Magnesite

With certain variations in detail, the same hypothesis of direct produc-

tion of antigorite by weathering has been favored by G. H. O. Volger in

1855, A. D’Achiardi in 1874, F. Becke in part in 1878, J. D. Dana in 1883,

H. Rosenbusch in 1892, T. G. Bonney and C. A. Raisin in 1904, G. Piolti

and Kk. A. Redlich in 1908. F. Cornu in 1905 has even pointed out the

‘passage of olivine into antigorite only on the rainy sides of the basalt

peaks of the Bohemian Mittelgebirge. R. Brauns™ in particular has

maintained a similar view, with the addition that the antigorite formed

during weathering has been at the same time further altered into “web-

skyite’—1 volume of the former into 1.61 volumes of the latter. As |

find, by recasting of his analysis, “webskyite,” with its supposed formula

H,R,Si,0,, + 6 aq., to be merely an impure aggregate of deweylite and

hyalite, Brauns has thus unconsciously approached the fact that deweylite

is an immediate and essential product of decay of olivine by weathering.

In his study of the decay of a serpentine rock of Bohemia by weather-

ing, a still closer approach to discovery of the genesis of antigorite was

made by A. Schrauf :?

“In the magnesite originating from serpentine, a magnesia hydrosilicate

forms a never-failing constituent.”

This he separated through removal of the magnesium carbonate by

digestion in acetic acid. On analysis of the residue from drying at 130°

C., he found the figures to correspond in molecular ratios to those of

antigorite, H,Mg.Si,0,, in predominance, though leaving 4 per cent. of

“free or hygroscopic water”! This appears to be almost the only instance

on record of claimed detection of antigorite among the products of rock

decay. As it happened, by that 4 per cent. apparently of superfluous but

actually of combined water, he missed the identification of the real hydro-

silicate present. An easy recasting of his analysis, on the basis of the

Ff. W. CLARKE: The Data of Geochemistry, 575, U. S. Geol. Sury. Bull. 491. Wash-

ington, 1911. :

uN. Jhrb. f. Min., Beil.-Bd. V, 318-324. 1887.

12 Zts. f. Kryst. u. Min., VI, 349. 1882.

28 ANNALS NEW YORK ACADEMY OF SCIENCES

combined water, shows that his dried residue consisted to 97 per cent. of

deweylite, H,,.Mg,Si,O,,, without any antigorite.

FORMATION OF ANTIGORITE DIRECTLY FROM OLIVINE BY THERMAL

ALTERATION

The development of newly formed antigorite among the products of

weathering was indeed long ago questioned by Ebelmen and others. T. 8.

Hunt declared its entire absence from the weathered coat over the peri-

dotites at Montreal, Canada. G. P. Merrill and T. H. Holland also have

held that it is never found as a weathering product of olivine, or as a

constituent of laterite. Therefore, hypotheses have been devised at the

other extreme, according to which the genesis of antigorite directly from

olivine has been effected solely in a deep-seated zone of special hydration

below the belt of weathering. This may have progressed as ‘common

hydrometamorphism,” at a moderate thermal temperature and depth,

under the influence of moisture permeating rocks below the ground water

level, such waters not favoring oxidation and containing no great amount

of carbonic acid. “Being an essentially deep-seated process, serpentini-

zation should certainly not be referred to weathering’ (W. Lindgren).

Its evidences are found in the entire absence of oxidation during the

passage of olivine into antigorite (G. P. Merrill, 1899); in the greater

production of magnetite than hematite from the iron oxide in ferriferous

olivine, thus pointing to the scarcity of atmospheric oxygen during the

hydration of that mineral into antigorite (J. H. Pratt and J. V. Lewis,

1905).

Other writers look to a still deeper zone of alteration to account for

the high water content of antigorite, as indicating connection with oro-

genic processes (Rosenbusch, 1901): there are evidences of pressure,

particularly in alteration from augite, which has served as a most im-

portant factor in the development of antigorite (T. G. Bonney, 1908) ;

with the characteristics of a deep-seated process, due to waters or vapors

coming from considerable depths, or even constituents of the magmas at

the time of their intrusion, which may be distinguished as hydrometa-

morphism (G. P. Merrill, 1899) ; an alteration which may have been the

effect of prolonged submergence in sea-water under high pressure (T. H.

Holland, 1899).

The variety of peridotite “stubachite” has been attributed to

“a post-volcanic, perhaps pneumatolytic process, following a period of pneu-

mato-hydrogenic action,” *

13), WEINSCHENK : N. Jhrb. f. Min.. I, 226. 1895.

JULIEN, GENESIS OF ANTIGORITE AND TALC Xe)

even though quite free from the mineralizers, etc., characteristic of that

process. It consists of a crystalline aggregate of olivine and antigorite—

the latter designated as “primary,” 17. e., of supposed contemporaneous

intergrowth with the olivine.

All the foregoing forms of the hypothesis of limitation of antigorite-

genesis to a deep-seated zone are, in my judgment, controverted by in-

ternal evidence, the common survival of deweylite in the chemical compo-

sition and the common association of chrysotile, each with a genetic his-

tory essentially connected with lateritic decay.

Not having yet found any analyses of “stubachite,” we have at least the

evidence that it is accompanied by an abundance of chrysotile, together

with “schweizerite,” a substance shown by its analyses to consist of a mix-

ture of massive antigorite, chrysotile and nemalite. “Stubachite” there-

fore appears to pertain to a peridotite (dunite) once partly saturated

with deweylite, brucite and sepiolite in the belt of weathering, which have

been later converted respectively into crystalline antigorite, chrysotile and

talc, at a temperature far less than that attending pneumatolytic action.

DIRECT HYDRATION BY AGENCIES WITHIN TWO BELTS

On account of the strong alliance, rightly suspected, of the associations

and characteristics of antigorite with the processes and products both of

the belt of weathering and of a more deep-seated region, other writers

would embrace a broader zone as the location for conversion of olivine

directly into antigorite. As this has been expressed by Van Hise :4

“Serpentine is a product of the zone of katamorphism, including both the

belt of cementation and the belt of weathering.”

In these hypotheses, the dual character is applied only to the locations

and the range of conditions considered requisite for completion of a single

process for derivation of antigorite directly from olivine. This is shown

by the fact that, in every case, a single equation suffices these authors to

explain the supposed reactions. There is a general vagueness concerning

the actual process, but no questioning of its essential unity of reaction.

For the above view, based upon the apparent simplicity of direct addi-

tion of water and oxygen to produce antigorite, the following reactions,

among others, have been suggested by Van Hise :*®

3 Mg,Fe,Si,0,+4 H,O +2 O=2 H,Mg,Si,0,+ 2 Fe,0,+ 2 SiO,

Olivine “Serpentine” Magnetite Quartz

4 Op. cit., p. 349.

1SiOp\ cit., p. 310.

30 ANNALS NEW YORK ACADEMY OF SCIENCES

Here, as in most equations ‘which have been suggested in discussions

of mineral genesis, the initial colloid condition of most products of min-

eral decay has been disregarded. Besides this, the minerals assumed ap-

parently as derivative within the belt of weathering—antigorite, magnet-

ite, hematite—are those which have surely taken their birth or acquired

crystalline form in a lower and thermal belt*of alteration. The difference

of view on the common products of olivine decay (omitting double salts)

within the belt of weathering may be contrasted as below:

By common hypothesis. By observation.

. Colloid silicic hydrates; amorphous hyalite

uartz, hy: Cerner ota cic eee d ip. °

Quartz, hyalite, opal \ chaleedony ; quartz.

Colloid or amorphous manganese hydrate,

IRVTGIUSILE Mercier. Cute c dhe oats hydroecarbonates, carbonate and hydrc-.

silicates; pyrolusite.

= Be Colloid or amorphous nickel hydrates, hydro-

= ¢ > “y. \ % e poor

Genthite, garnierite.............. ; { carbonates and hydrosilicates (connarite).

drocarbonate, carbonate, hydrosilicate, in

part amorphous; siderite.

Colloid ferric or ferroso-ferric hydrates, hy-

‘Siderite, magnetite, hematite .....

hydrocarbonates and hydrosilicates; cal-

cite, dolomite.

Colloid or amorphous caleium carbonate,

‘Calcite, dolomite............ Teoestishe

Amorphous magnesia; amorphous magne-

Brucite, magnesite, hydromagnesite. sium hydrate, hydrocarbonates, carbon-

ates; brucite, hydromagnesite, magnesite.

Colloid magnesium hydrosilicates (dewey-

Antigorite, talc, deweylite, sepiolite. { lite, sepiolite), in part amorphous.

In the equations above given to illustrate the supposed direct conver-

sion of olivine into antigorite, the calculated volume changes varied from

+ 12 to + 37 per cent. To this expansion and subsequent shrinkage, the

phenomena of fracture, gliding, slickensiding, etc., observed in many

bodies of serpentine, have been attributed by G. P. Merrill and others.

DuAL PROCESSES IN GENESIS OF TALC AND ANTIGORITE

The object of the present paper is to distinguish and define my con-

clusions (without the evidences) concerning the dual processes as well as

dual regions of alteration—first, the belt of weathering, and later the

lower region, connected with development of both tale and antigorite

from olivine.

Three other minerals, hitherto treated merely as interesting accessories

during development of tale and “serpentine”—viz., brucite, sepiolite and

deweylite—now offer their claim as essential elements, in amorphous or

colloid form, to the genesis of the two minerals in question. The key to

JULIEN, GENESIS OF ANTIGORITE AND TALC 31

that genesis, I believe, lies in the relationship in each case of a colloid

magnesium hydrosilicate (Type I), originating from decay of olivine or

other ferro-magnesian mineral, during weathering, to a complementary

hydrosilicate (Type IL), containing more silica and magnesia and less

than about half as much water, into which the former has been afterward

converted in a lower region of metamorphism.

The four known magnesium hydrosilicates may be thus arranged to

show this relationship of the two types:

Percentage

Type. Derivation. Product. Formula, composition

(disregarding n aq.).

SiO, | MgO | H,0

Iie From decay of | Sepiolite | H,Mg,Si,0,)+7 aq...| 60.80 | 27.10] 12.10

olivine. (colloid).

it Fromalteration of | Tale....... le Mies Ones cab oan 62.00 | 33.10] 4.90

sepiolite.

Te From decay of | Deweylite | H,,.Mg,Si,0,,+ n aq..| 40.20 | 35.70] 24.10

; olivine. (colloid).

JL From alterationof | Antigorite..| H,Mg,Si,O,.......... 43.50 | 48.52 | 12.98

deweylite.

The processes involved in the development of these four minerals in

nature may be represented in part by the following equations, confining

our attention to the single mother-mineral, olivine, out of the twenty-

three known to pass into sepiolite and deweylite.

For tale:

4 MgFeSiO,+ 8 H,O+2 O+7n aq. =(H,Mg,Si,0,) +n aq. )

Olivine Colloid sepiolite

+ 2 (H;Mg0,-+-n aq.) + (HgFe,0,+-n aq.) + (H,Si0,+-n aq.)

Amorphous magnesium hydrate Colloid ferric hydrate Colloid silicic hydrate

Kssential volume change (disregarding nm aq.) = -+ 67.40 per cent.

Then in a lower region:

3 (HyMg,Si,0;)+ ” aq.) + A=2 H,Mg,Si,O,, +Si0, +4 H,O+n aq.

Colloid sepiolite Heat Tale Quartz

In massive form the normal rock aggregate, steatite, has thus become

developed, a mixture of tale and quartz.

Essential volume change*® = — 32.96 per cent.

For antigorite:

8 MeFeSiO, +21 H,0+4 O-+n aq. =(H,,Mg,Si,0,,-+n aq.) +4( H,Mg0, +n aq.)

Olivine Colloid deweylite Magnesium hydrate

+ 2(H,Fe,0,+ n aq.) +5 (H,SiO, +n aq.)

Colloid ferrie hydrate Colloid silicie hydrate

16 Without regard to n aq.

32 ANNALS NEW YORK ACADEMY OF SCIENCES

Kssential volume change’® = + 80.31 per cent.

It will be noted that incipient development of both sepiolite and dewey-

lite from mineral decay has been attended by separation of a certain

amount of magnesium hydrate. This was not understood, except by Roth

and Teal, or included in the formulas previously given; it may serve as a

test of the truth of the reaction here set forth.

Later, with subjection of deweylite to thé thermal conditions in a

lower metamorphic belt, the complementary process of alteration has

taken place :

3 (H,Mg,Si,0,_ +7 aq.) +A—4 H,Mg,Si,0,+Si0, + 10 H,O-+n aq.

Colloid dewey lite Heat Antigorite (94.8 Hyalite

per cent.) or quartz,

Hssential volume change’® —= — 32.79 per cent.

Reference has already been made to commonly accepted views concern-

ing dynamic effects upon bodies of serpentine by the changes of volume

in progress during passage of minerals into talc and antigorite. It is now

apparent that admission into the equations of the hydrated colloids of

seplolite, deweylite, etc., actually found in nature, would involve an early

hypothetical expansion far greater than hitherto estimated. On the

other hand, the later physical changes which have preceded the birth of

tale and of antigorite have generally culminated in notable contraction

of the rock mass. We have to do here, however, with more than chemical

reactions. The attendant physical processes of solution, leaching, trans-

port and migration of soluble constituents, and their later alteration in

a deeper thermal zone, have resulted in a complex fissuring, and often in

an amount of contraction which has decidedly offset the expansion from

early chemical changes. The observed evidences of internal disruption

and movement in bodies of serpentine may be therefore everywhere ex-

plained, I judge, by successive throes of expansion and contraction—e. g.,

at Staten Island and New Rochelle, New York; Montville and Hoboken,

New Jersey, and Thetford, Canada—and also by local strains and faults

produced by orogenic disturbances.

For precise definition of processes above considered, I think we need

differentiation of the following terms:

Decay of rocks, to express the result of operations within the belt of

weathering, disintegration, oxidation and extreme hydration. Among

the more important products are the colloid magnesium hydrosilicates of

the first type (colloid deweylite, sepiolite), magnesium oxide, hydrate

and giobertite, besides various forms of ferrous and ferric hydrates, hy-

drocarbonates, ete.

16 Without regard to n aq.

JULIEN, GENESIS OF ANTIGORITE AND TALC 33

Alteration, to express the interchanges and consequent new formations,

with great loss of water, which take their birth in a more deeply seated

region. The common products are the magnesium hydrosilicates of the

second type (talc, antigorite), hardened deweylite, forms of limonite,

gothite, turgite, hematite, etc.

Decomposition (Zersetzung of Roth), to express the molecular disso-

ciation, still more complex interchanges, and still greater to complete

dehydration, which have ensued within the zone of anamorphism. Ex-

amples of these products are periclase, spathic magnesite, dolomite,

siderite, breunerite, regenerated olivine (boltonite, forsterite), specular

iron, magnetite, etc.

In regard to the term “hydrometamorphism,” whether in the sense of

Lindgren, referring to the action of meteoric or vadose waters, or in that

of G. P. Merrill, referring to the action of waters from deep-seated

sources or from magmas, I find no application for it below the belt of

weathering. There only has originated the highest hydration; below it,

every change has been attended by progressive loss of water.

GENESIS OF CHRYSOTILE AND RETINALITE

In Plate VI, a well-known laminated variety of asbestos-rock from

Thetford, Canada, is presented. Here lie the leaves, silver and green, in

long succession, of the book of the history of asbestos, waiting for inter-

pretation of the mystery of its origin.

If “serpentine,” as long believed, is a colloid, incapable of crystalliza-

tion, is this fibrous chrysotile but an alteration product from asbestiform

amphibole or bronzite? Or are these fibers only “serpentine” wires, pro-

truded through pores in the vein walls, like those of metal in the arts?

Or, along fault planes, has the serpentine been rolled out and sheared

into these silky threads? Or, if there be a crystalline paramorph of

amorphous “serpentine,” is this its fibrous deposit from lateral infiltra-

tions into rock fissures? Is it possible that these have been generated

by diamagnetic secretion along the vein walls, expelling into the median

fissure of the vein the feebly magnetic brucite, poor in iron, and the

diamagnetic calcite? Or are the fibers in fact capillary or acicular crys-

tals either of “serpentine” itself or of its paramorph, thrust from one

wall to the other, or grown simultaneously inward from each wall?

It is doubtful whether any one of these conjectures has proved satis-

factory even to its author.

Toward solution of this part of Delesse’s enigma, in my turn, it re-

mains to sketch some of the migrations and transformations of the

magnesian derivatives from rock decay, as they oozed downward from

34 ANNALS NEW YORK ACADEMY OF SCIENCES

laterite into fissures and occupied them as vein deposits. Magnesium

hydrate, the most soluble and mobile, was the earliest to form a coating

on each wall, sometimes filling up the entire fissure. So originated the

veinlets of brucite, crystalline at Hoboken, New Jersey, and crystallized

at Hopansuo, Finland, and Texas, Pennsylvania.

The next stage in the process has been connected with the tendency of

brucite, when subjected to rock-strains, to molecular rearrangement in

direction of the pressure. Its grains become shot through with parallel

lines, without regard to the cleavage, and at last transformed into aggre-

gates of fine fibers. Thus brucite has frequently passed into its fibrous

allomorph, nemalite, with fibration normal to the vein walls, well shown

at Hoboken and Montville, New Jersey, Xettes in the Vosges, etc. From

solution in carbonated waters, veins of the less soluble carbonates, hydro-

magnesite, magnesite, etc., have been also produced, or from the action

of such waters on brucite already deposited, as at Hoboken, many localities

in California, ete.; or where nemalite has occurred, coating each wall of

a vein, the interspace remains sometimes filled up with laminated brucite,

as at Hoboken, or with magnesite, as at Montville.

Next, by passage of siliceous waters, crystalline brucite has been con-

verted into its antigorite-pseudomorph, marmolite (as shown by Volger

and others) at Hoboken and elsewhere, and its crystals into “thermophyl-

lite” at Hopansuo. In the marmolite of Hoboken, pearly flakes of un-

altered brucite can be sometimes plainly distinguished. This again im-

plies the intervention of deweylite, and there is abundant evidence of its

generation by the following process—reaction of free magnesium oxide,

hivdrate or carbonate, or of dolomite, with percolating solutions of silicic

hydrate or of alkaline silicates. Of the resulting equations it will suffice

here to offer the following:

4 H,MgO,+3 (H,SiO;-+n aq. ) = (H,.Mg,Si,0,,+ aq.) + H,O

Magnesium Silicie hydrate Colloid deweylite

hydrate

Volume change (disregarding n aq.) == — 3.75 per cent.

Deweylite of this origin, subjected to thermal conditions, passed into

antigorite by the reaction already explained.

Where silicification of nemalite took place, it was converted into dewey-

lite with pseudomorphous fibration, and this, by later thermal action,

into its antigorite-pseudormorph, chrysotile. The passage of nemalite

into chrysotile, supposedly direct, was detected by G. H. O. Volger'® in

specimens from Hoboken in his cabinet, but the intervention of deweylite

was not suspected.

16 Entwicklung der Mineralien der Talk-Glimmer Familie, Ziirieh, 254-270, 1855.

JULIEN, GENESIS OF ANTIGORITE AND TALC 85

The office of deweylite has not ever been recognized, doubtless in part

on account of the difficulty of detection of a colloidal amorphous sub-

stance, and in part of its general alteration into antigorite. Evidence

of the latter change is revealed by the frequent partial survival of dewey-

lite grains in intermixture, and also by the very chemical composition of

many specimens of antigorite.

For example, T. 8. Hunt made among others the following analysis'*

of chrysotile

“from a narrow vein traversing the Eozoon rock of Petite Nation seignory,

Quebec: silica, 43.65; magnesia, 41.67; protoxyd of iron, 1.46; water, 15.48;

100.16.”

He commented thus, with surprise, on his results:

“these serpentines from the Laurentian limestones are remarkable for their

freedom from iron oxide, for their large amount of water, and their low specific

gravity.” ®

These anomalies are explained by the results of my recasting of his

analysis: antigorite, 95.13; deweylite, 4.63; hyalite, 0.40. In develop-

ment of the pseudomorphs, marmolite from brucite and chrysotile-asbes-

tos from nemalite, a steady progression in contraction is shown, to about

one-third of the volume, without disturbance by expansion, from the

original magnesium hydrate to the final product, antigorite. This seems

to be correlated with the perfect preservation of all structural details,

even to the most delicate features of nemalite.

This genetic history of chrysotile, if accepted, enables us to use its

occurrence as a test of conditions which have always prevailed during

genesis of antigorite from decay. Its general association with the other

forms of that mineral, even at the “stubachite” locality, establishes iden-

tity of origin through the dual processes already explained.

Colloid deweylite, the magnesian companion of brucite in migration

from laterite, has likewise been concentrated in simple veins, as at Texas,

Pennsylvania, Bare Hills, Maryland, etc. Where a portion of the dewey-

lite has escaped the subsequent alteration, its intermixture has produced

the waxy, translucent variety of antigorite, retinalite, common at many

localities. Its analyses invariably reveal an unusually high percentage

of combined water, due entirely, as shown by the recasting, to the pres-

ence of several per cent. of unaltered dewevlite. Moreover, specimens are

not uncommonly sprinkled with visible grains of that mineral.

“Rpt. Prog. Geol. Sury. Can., 205. Ottawa, 1866.

LAIN SOUL Cle (2) ekki GS.) L864:

36 ANNALS NEW YORK ACADEMY OF SCIENCES

CoMPOSITE VEINS

While the separate deposition of both magnesium hydrate and colloid

deweylite has frequently taken place, as described, in simple veins of each

mineral, nevertheless their normal and probably more common mode of

conveyance from laterite downward has been in intermixture. Com-

posite veins have resulted by separation of “successive deposits of each

from this mixture, and not, as might first be judged, by a series of de-

posits upon each wall, now of one mineral, now of the other, in alternation.

A simple form has consisted of a vein with wall coatings of brucite

or nemalite, with a middle sheet of deweylite. By silicification, the wall

coatings have passed into fibrous deweylite, and this, by later alteration,

into chrysotile-asbestos, with a sheet of massive antigorite or retinalite

intervening, as at Portchester, New York, ete.

The reverse order of arrangement has been also observed, with sheets

of massive antigorite or retinalite (7. e., originally deweylite) coating the

walls, and a central sheet of brucite, nemalite and sometimes calcite, as

in the Vosges; or with a central sheet of nemalite, in part chrysotile, as

at Hoboken.

A proof of the above suggested intermixture of the two magnesian

components is yielded from study of analyses of retinalite. A specimen

“associated with eozoon” at Calumet, Quebec, gave T. S. Hunt the follow-

ing results: silica, 41.20; magnesia, 43.52; ferrous oxide, 0.80; water,

15.40; 100.92. My recasting of this reveals the following constitution :

antigorite, 83.90; deweylite, 11.76; brucite, 5.24. That is to say, a nota-

ble portion of each of the original magnesian components has escaped

alteration and remains intermixed with the antigorite.

An interesting example of such intermixture has been observed in a

symmetrical asbestos vein, two inches in width, in dark green serpentine

containing particles of chromite, on lot 13, Range V, Thetford, near Rob-

ertson station, Canada.‘® The first deposit on each wall has been a thin

layer of dark blue antigorite (originally deweylite) “with grains of

chromic iron” ; then a layer of chrysotile (originally brucite), with fibra-

tion normal to the wall; then a thin layer of pale-green retinalite (orig-

inally deweylite) ; and a central sheet, about +§ inch thick, of dark blue

antigorite (originally deweylite mixed with magnesium hydrate), along

the middle of which run minute seamy partings of chrysotile (originally

brucite) parallel to the plane of the vein.

A succession of four passage solutions of magnesia is here indicated :

first, the colloid hydrosilicate; then the hydrate; then again the hydro-

19 f, CIRKEL: Asbestos, p. 28, Fig. 6. Ottawa. 1905.

JULIEN, GENESIS OF ANTIGORITE AND TALC ey

silicate ; and then the main solution, or mixture of the two components.

During consolidation and contraction of the last deposit, disassociation

of the hydrate took place by diffusion into the shrinkage crevices near the

middle of the vein. In fact, however, the separated deposits here found

on the walls are probably, like those next to be described, derivatives from

mixed solutions, by disassociation higher up the vein.

The most complex variety of composite veins is that represented in the

illustration (Plate VI) and ordinarily found in proximity to laterite

rich in magnesian silicates. It consists of a lamellation, in abundant

repetition, of thin alternating sheets of chrysotile and retinalite, the

thickest near the vein-wall and thinning outwardly; the first very thick

layer of retinalite on the vein-wall is absent, having been broken from

the specimen. In structure and development the variety is essentially

identical with the lamellation of antigorite (“eozoon”) in dolomitic lime-

stone at Grenville, Canada, and other localities, although there the ma-

terial of alternation with retinalite is calcite in place of chrysotile. In

each case, I have concluded, a rhythmical process of unilateral vein depo-

sition from laterite solutions has originally taken place—every pair of

lamellee comprising a film of colloid, magnesium hydrosilicate, with one

of crystalloid, magnesium hydrate here and calcite in the Canadian oc-

currence, separated from the colloid by dialysis.

The rhythm of deposition has apparently been due to limitation of the

flow into the vein fissure of the mixed solution of the two magnesian salts

in meteoric waters to a certain period of accumulation, perhaps the rainy

season of the year. After spreading upon the surface of the wall, dis-

association began, the colloid being left clinging as a new coat upon the

wall, while from its outer boundary—perhaps through a dried film serv-

ing as a septum—the crystalloid magnesium hydrate became diffused

more or less completely by dialysis and so formed the companion coat of

each pair of alternations. The amorphous magnesium hydrate readily

crystallized into brucite, and this, by subsequent pressure—perhaps by

rock strains, through expansion in neighboring portions of the mass—

was converted into its fibrous variety, nemalite. Other fissures have been

opened by contraction of the rock more or less transversely to this lamella-

tion, but these have been generally filled with magnesium hydrate, amor-

phous and crystalline, as simple veins, changed in turn into nemalite by

rock strains.

By later silicification or alteration under thermal conditions, all these

lamellz and transverse veins have become altered—nemalite into chryso-

tile-asbestos and deweylite into massive antigorite, in part retinalite.

38 ANNALS NEW YORK ACADEMY OF SCIENCES

CONCLUSIONS

In review, then, magnesia, in hydrated or carbonated condition, and

deweylite and sepiolite, in colloid form, have always been the only mag-

nesian derivatives from laterite, with tendency to early migration and

transport, in virtue of their solubility.

Antigorite and tale, on the other hand, ctystalline and never colloid,

have merely served as insoluble fixatives to harden and record the trans-

formations of their mobile and protean predecessors. Chrysotile is but a

pseudo-fibrous variety of antigorite—in fact, a pseudomorph in antigorite

after a pseudomorph in deweylite after nemalite, the fibrous form of

brucite. |

To the list of rock-making minerals, brucite, deweylite and sepiolite

need to be added as important accessories.

The evidences in confirmation of these views from field observations,

optical examinations, etc., together with a review of the literature of

brucite, serpentine, antigorite, and the hydrous magnesian minerals, have

been gathered for presentation in a separate monograph.

DEPARTMENT OF GEOLOGY,

CoLuMBIA UNIVERSITY.

ANNALS N. Y. ACAD. SCI. VOLUME XXIV, PLATE VI

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PRESS OF JUDD & DETWEILER, INC., WASHINGTON, D. C.

ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIV, pp. 39-113

Editor, Epmunp Ottis Hovey

A STUDY OF THE CHANGES IN THE DISTRI-

BUTION OF TEMPERATURE IN EUROPE

AND NORTH AMERICA DURING

THE YEARS 1900 TO 1909

HENRYK ARCTOWSKI

NEW YORK

PUBLISHED BY THE ACADEMY

2% JUNE, 1914

THE NEW YORK ACADEMY OF SCIENCES

(Lyceum or NAturRAL History, 1817-1876)

Orriorrs, 1914

President—GuorcE FREDERICK Kunz, 601 West 110th Street

Vice-Presidents—CHARLES P. Berkey, RaymMonp C. Ospurn,

CHARLES BASKERVILLE, CLARK WISSLER

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Editor—Epmunp Otis Hovey, American Museum

SECTION OF GEOLOGY AND MINERALOGY

~ Chairman—Cuartes P. Berkey, Columbia University

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SECTION OF BIOLOGY .

Chairman—Raymonp C. Ospurn, 557 West 124th Street

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Natural History, 77th Street and Central Park, West. \

[ANNALS N. Y. Acap. Scr., Vol. XXIV, pp. 39-1138. 27 June, 1914]

A STUDY OF THE CHANGES IN THE DISTRIBUTION OF

TEMPERATURE IN EUROPE AND NORTH AMERICA

DURING THE YEARS 1900 TO 1909?

By Henryk ARCTOWSKI

(Presented in abstract before the Academy, 2 February, 1914)

CONTENTS

, Page

MrdtMO MUCHO Mrs r<yeyepsyaiistacsics sicisie) egots yore ope lai te,as(0)o)8/ysie'ls & Spe eperersis. oie, 0 oblate e.e.ene.'sialeseve 39

Mong-raneer variations: Of temperatures... sas. «soc sccsic ce aeccceccececseec 41

European temperature data for 1900-1909............. ccc cc ec cccccccecs 50

American temperature data for T9OOH1909. .. oc. ccc ccc cw lec e o's ieee tessiovers 73

WONSECITAV CHITA SS 5iore a isotsioievetdvevats obsisieuaiis feiede (ola, evalevectielel oroiel oun eles c eleieis ic « Sieiestels 87

Consecutive temperature curves for several stations in the United States... 97

About temperature variations and the changes of the arctic ice conditions. 104

CONTIN ST OMS orca ter tretevc ete eka are ah ua eraysege- asec ohare oes Siicisl dlayanahavensagevaveraveve tel Scavee(eiel ere Wb

INTRODUCTION

Considering the sefies of annual means of temperature, of given local-

ities, we notice everywhere more or less important fluctuations. The

curves expressing graphically the succession of figures show perfectly

well pronounced variations at certain localities differing completely from

other variations of other localities. Some curves go down while others

go up, and the length of time separating the maxima varies from one

curve to the other.

It is impossible, therefore, to discuss the question of climatic variations

with only the data of a selected number of stations. All available data

have to be taken into consideration, and the problem has to be studied

geographically. The problem of the variations of terrestrial temperature

is, indeed, absolutely similar to the problem of the mean elevation of the

surface of the earth crust. The precision gained in the appreciation of

the mean elevation of a continent depends on the precision of the utilized

hypsometrical maps. The precision of an estimate of the mean depth of

an ocean depends on the accuracy of the bathymetrical map, on the num-

ber of soundings. Since, in the case of temperature, we have also to deal

1 Manuscript received by the Editor, 4 March, 1914. ; (39)

LIBRA

NEW

BOTANICA

GARVEN

40) ANNALS NEW YORK ACADEMY OF SCIENCES

with depressions below. the average and elevations above, the knowledge

of the extent of the areas covered by positive and negative departures is

evidently more necessary for the discussion than the figures for some

isolated stations, where the temperature conditions may or may not cor-

respond to the average conditions of the surrounding countries.

The work done for a previous publication was the mapping of all the

temperature data [ could obtain for the years’ 1891 to 1900.

Considering the means of the decade, 1891-1900, as being quasi-

normal values, I have formed for each year and each station the depar-

tures from these means. These annual departures have been inscribed

on maps, and equideparture lines have been drawn. ‘The areas of positive

departures have been called thermopleions, the areas of negative depar-

tures, thermomeions or antipleions. ‘The result of the discussion is that

the year 1900 was a year of predominant thermopleions, the year 1893,

on the contrary, a year of most predominant antipleions. Taking the

probable areas into consideration, as well as the probable excess and

deficiency of temperature, I found that the difference in temperature

between these two years must have been at least 0°.5 C.

This was the main result of my memoir “L’enchainement des varia-

tions climatiques,” ? published in 1909. This practical demonstration

of the fact that the temperature of the earth’s atmosphere does not remain

constant leaves a very important question open for discussion.

The annual departure maps of successive years showed in many cases

some striking similarities in the mutual relationship of pleions and anti-

pleions. I presumed, therefore, that pleions might persist from year to

year and that they displaced themselves. In my further researches, I

found it necessary to simplify the reasoning by adopting a way of ex-

pressing graphically the change of a given annual mean into that of

the following year. To avoid the more or less regular annual variation,

we have to take yearly means, but it makes no difference how we count

the year, as long as we compare means of 12 consecutive months. By

making consecutive yearly means for the one-year periods beginning with

January, February, March and so on, and by comparing the curves ex-

pressing the succession of the figures, we can see how a negative departure

of a given year passes progressively to a positive departure of another

year.

I have published such consecutive temperature curves for the entire

series of observations recorded in Batavia* and New York,* and portions

2 HENRYK ARCTOWSKI: L’enchainement des variations climatiques. Bruxelles, 1909.

2 Op. cit., p. 32.

4 HENRYK ARCTOWSKI: On Some Climatic Changes Recorded in New York City. Am.

Geog. Soc. Bull., Vol. 45, p. 117.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 4]

of the curves for many other places are reproduced in this memoir. ‘Two

facts of some importance are clearly demonstrated by all these curves:

1) Although there are some most interesting agreements with the curve

expressing the sun spot cycle, this cycle cannot be considered as being the

main factor producing the pleionian variations, simply because the pleionian

erests and depressions of the temperature curves repeat themselves three to

four times more often than the maxima and minima of the solar curve.

2) The temperature curves for distant stations, belonging to absolutely

different climates, present in certain cases such. striking coincidences that it

is impossible to ascribe them to simple chance circumstances. I may add that

the consecutive curves of rainfall, of sunshine records and of atmospheric

pressure display also pleionian variations and demonstrate the fact that we

have to deal with more or less periodical alterations of the atmospheric circu-

lation.

In order to make comparisons, a standard curve was necessary. ‘The

records of the exceptionally undisturbed climate of Arequipa, in Peru,

gave this necessary standard.*

The consecutive temperature curve of Arequipa, for the years 1900-

1910, shows four characteristic crests and four depressions. The curve

of Bulawayo, in Rhodesia, is absolutely similar to the Arequipa curve.

The same may be said about the curve obtained from the Mauritius

observatory figures, and for Tananarive, Madagascar. Batavia, Java, dis-

plays also an indisputable resemblance with the Arequipa curve. North

of the equator, Havana gives a similar curve, but the data of San Juan,

Porto Rico, give a slightly retarded curve, and this is a most interesting

fact. Indeed, the pleionian crests of Porto Rico could not be retarded if

these temperature anomalies did not have a tendency to persist combined

with a tendency of displacement.

The question, therefore, was whether all pleionian variations observed

all over the world were not in immediate correlation with the Arequipa

variation. Together with this question, it was necessary to solve the

problem of the displacement of pleions.

LONG-RANGE VARIATIONS OF ''EMPERATURE

The waves expressing the changes of temperature are of different

amplitude and different length. If we take monthly means of tempera-

ture, we do not take into consideration the groups of cold and hot waves

which characterize the changes of weather, and we eliminate also the

short diurnal waves of the more or less regular daily variation. If we

5 HHNRYK ARCTOWSKI: The “Solar Constant” and the Variations of Atmospheric Tem-

perature at Arequipa and Some Other Stations. Am. Geog. Soc. Bull., Vol. 44, p. 598.

42 ANNALS NEW YORK ACADEMY OF SCIENCES

take yearly means, the groups of exceptionally cold or exceptionally hot

months are also eliminated, at least to a certain extent. In fact, in a

yearly mean, of a normal value, the effect of a couple of abnormally cold

months may be balanced by a couple of very hot months, so that the

yearly mean of temperature may remain normal.

The advantage of consecutive twelve mqnthly means® over the calendar

yearly means is that we can detect the effect of some of the shorter waves

on a yearly mean, giving us at the same time the possibility of locating

seasonal anomalies. Likewise, if we take the consecutive means of groups

of yearly means we will disclose, easier than in any other way, the suc-

cessions of colder and warmer periods during various lengths of time.

Admitting, for the pleionian variations, a period of from two to five

years as the unit of time, we will say that shorter climatic variations are

brachychrone and those that are very much longer than these pleionian

variations are macrochone. Besides the ordinary pleions and antipleions

or thermomeions, therefore, we will have to speak of brachypleions and

macropleions, of brachymeions and macromeions.

The curves of the following diagram (Fig. 1) may serve to explain

more clearly the difference between macropleionian, pleionian and brachy-

pleionian waves.

The first curve shows the succession of consecutive annual means for

Arequipa. A, B, C, D, are pleionian crests, preceded and followed by

antipleionian depressions. With the exception of the second depression,

which may have been accentuated by the presence of great quantities of

volcanic dust in the higher layers of our atmosphere,’ the depressions, as

well as the crests, show a striking tendency to decrease from 1901 to 1909.

®] think that the expression ‘‘consecutive means’’ is just as comprehensible as the

expression ‘overlapping means,” “progressive means” or “moving averages.”

WILLFORD I. KING, in his “Elements of Statistics’? (New York, 1912, p. 166), uses

exclusively the term ‘“‘moving average.”

As far back as 1841 LUKE Howarp, “On a cycle of eighteen years . . .”’ (Philos.

Trans. Royal Soe. of London for 1841, p. 277), utilized consecutive means and called

them “averages on successive cycles.”

H. H. CuayTon, in his paper “A lately discovered meteorological cycle’ (Am. Meteor.

Journ., Vol. 1, p. 180, 1884), used the perfectly comprehensive expression ‘“‘means of

every twelve consecutive monthly means.”

7 Many papers have been published recently, concerning the question of the influence

on meteorological conditions of volcanic dust, present in the higher layers of our atmos-

phere. Some information upon the effect of this cause on the observed variations of the

“solar constant’? may be found in the following papers :

Cc. G. ABBoT: “Do voleanie explosions affect our climate?’ (Nat. Geogr. Mag., Vol.

24, p. 181. 19138.) C. G. ABBor: “The solar constant of radiation.’ (Trans. Inter-

nat. Union for co-op. in solar research, Vol. 3, p. 201. 1911.) C. G. Aprot, F. E.

FOWLEP and L. P. AuprRICH: ‘‘The variation of the sun.’ (Astronomische Nachrichten,

Vol. 194, p. 481. 1913.)

Cc. G. ApBot and F. E. FowLe: ‘Volcanoes and climate.” (Smithsonian Miscellaneous

Collections, Vol. 60, No. 29. 1913.)

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 43

The punctuated lines show this variation, which is absolutely distinct

from the pleionian variation and may have a period of 18, 19 or any

other number of years. The length of time makes no difference, the only

important fact being that such a long range or macrochronic variation

exists. By eliminating the effect of the pleionian variation, we obtain

macropleionian crests and macromeionian depressions, but it is evident

that for that purpose a long series of meteorological records is necessary.

TERY:

EES LTE

Fig. 1.—Diagrams of consecutive annual and consecutive monthly means of temperature

at Arequipa

On the other hand, the second curve of the diagram shows the succes-

sion of consecutive monthly means for the years 1906 and 1907 and dis-

plays brachypleions. In the case of Arequipa, the brachypleionian crests

have a mean period of about 55 days.

If we were absolutely certain that the pleionian variations of the equa-

torial regions were due to changes of the energy radiated by the sun, it

HpreBert H. KIMBALL: “Solar radiation, atmospherie absorption, and sky polarization,

at Washington, D. C.” (Bull. Mount Weather Observatory, Vol. 3, p. 69. 1910.)

: “The effect upon atmospheric transparency of the eruption of Katmai Vol-

cano.”’ (Month. Weather Review, Vol. 41, p. 153. 1913.)

——: “A return to normal atmospheric transparency.” (Journ. Washington Acad.

Sciences, Vol. 4, p. 17. 1914.)

W. J. HuMpHREYS: “Volcanic dust and other factors in the production of climatic

changes, and their possible relation to ice ages.” (Bull. Mount Weather Observatory,

Voll Gyipl wo 9135)

44 ANNALS NEW YORK ACADEMY OF SCIENCES

would be reasonable to restrict the use of the word antipleion to the

meions due to purely dynamical causes and occurring during the pleio-

nian years of the equatorial regions. In the present state of our knowl-

edge of these variations, however, it is advantageous not to make a dis-

tinction between the direct and the mechanically provoked pleions and

melons. ;

The graphic representation on maps of the positive and negative areas

of long-range variations of temperature gives the position and extent of

the macropleions and macromeions. In connection with the study of

these maps, expressing long-range variations, the following problems have

to be taken into consideration :

1) The existence of periods of a given number of years, as 18, 19, 35 or

some other number, having been admitted, it is necessary to verify to what

extent the variations of arbitrary selected stations may characterize long-range

variations for a given country or, let us say, the question is to know whether

macromeions and macropleions appear and disappear periodically.

2) Having admitted a presumably universal long-range variation, of about

thirty-five years duration, Briickner has called exceptional regions (Ausnah-

megebiete) some continental areas where the departures of lustra-means were

opposite to the admitted variation. If such is the case, we should observe

macromeions on these areas corresponding in time and location to macropleions

of the universal variation. The question is whether the maps justify such a

hypothesis.

3) Different authors, Blanford, Kremser, Lockyer, Hildebrandsson, Meinar-

dus and Mossman among others, have noticed perfectly characteristic seesaw

variations between given localities. In most of these investigations, only

seasonal variations have been studied. Supposing, however, that there is no

regular periodicity in the variations of long duration, we may ask whether

there are corresponding areas of simultaneous occurrence of the macrochronic

pleions and meions.

Satisfactory solutions of these three problems would advance very

greatly our knowledge of the climatic changes. I even think that a scien-

tific understanding of these changes would elucidate, to a great extent,

some of the difficulties encountered in the study of these very much more

important climatical variations which occurred in prehistoric times and

which are studied from the point of view of geological records,* and also

such historical variations as those which, recently, have been most suc-

cessfully studied by Ellsworth Huntington.

Unfortunately, the main difficulty lies in the lack of precision in our

meteorological records. In order to discuss the long-range variations of

® Die Veriinderungen des Klimas seit dem Maximum der letzten Biszett. XI Intern.

Geologen Kongress. Stockholm, 1910,

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 45

temperature in the United States, I took the tables of Frank H. Bigelow®

and, to my great astonishment, found that for some stations the depar-

tures of the annual means from the normal values are misleading.

The yearly mean temperatures of Chicago and Milwaukee, for exam-

ple, illustrate my assertion. On Bigelow’s tables the means of the first

decade of years are 49°.5 and 45°.7 F. For the years 1873-1882 we

have, therefore, a mean difference of 3°.8. The means of the last decade

(1896-1905) are 48°.3 and 46°.1, figures which give a difference of only

2°.2. Considering decades of years, the increase is 0°.4 in Milwaukee,

whereas there is a decrease of 1°.2 in Chicago. These stations are too

close to one another to admit such a disagreement of figures, and it is

evident that something is wrong in the records of either Chicago or Mil-

waukee. Of course, a difference of 1°.6 is not a very large figure and this

difference may be due entirely to the variations of the town influences.

The records of Port Huron, Detroit and Toledo may serve as another

example of misleading discrepancy. Considering again ten yearly means,

the differences between the means of 1876-1885 and 1886-1895 are 0°.1

for Port Huron, 1°.4 for Detroit and 2°.4 for Toledo. It seems highly

improbable that a decrease of temperature of 2°.4 could occur at Toledo

simultaneously with a decrease of only 0°.1 at Port Huron. Now, com-

paring the departures of overlapping ten yearly means, departures from

the general means or normals, we notice that one or two of these series

of observations must certainly be considered non-homogeneous.

Likewise, the departures of Knoxville compared with those of Cincin-

nati, Memphis and Augusta show plainly that the records of Knoxville

are unsatisfactory.

These examples demonstrate how cautious one has to be in dealing with

long-range variations of temperature. The changes of the mean tem-

peratures due to climatic variations of long duration are small and an

apparently insignificant cause of error may modify the values of a series

of observations to such an extent that the actual variation will be com-

pletely disguised. It is therefore easy to understand that even the best

available figures—such as those of Bigelow’s tables, for example—lead

only to a sort of rough approximation.

I will pass now to the exposition and discussion of the results of my

calculations.

On Bigelow’s tables, there are fifty stations having continuous records

from 1873 to 1905, but only five belong to the plateaux and Pacific coast,

namely: Cheyenne, Denver, Portland, San Francisco and San Diego. In

® Report on the temperatures and vapor tensions of the United States. U. S. Dept,

of Agric. Weather Bureau, Bull. S. 1909.

46 ANNALS NEW YORK ACADEMY OF SCIENCES

order, therefore, to have a better idea of the variations in the far western

states, I had to take fourteen more stations whose records begin a few

years later than 1873. I made, for these sixty-four stations, consecutive

totals of ten-yearly means and the departures of these totals from the

general or normal means of Bigelow’s tables, and then I inscribed the

figures so obtained on maps and drew the lines of equidepartures.

When one takes into consideration the fact that some of the departures

are obviously wrong, the series of observations not being homogeneous,

and when one looks on the maps and sees how far apart some of the sta-

tions are and how problematical these departures are, one arrives at the

conclusion that all that may be said about long-range variations of tem-

perature is to a great extent purely hypothetical.

It is undeniable that long-range variations exist, but a search for the

periods of these variations is at present hardly justifiable, as an inspection

of my maps demonstrates at once. The oscillations of temperature are

indeed the product of a dynamical phenomenon, and it is of course only

in the case of stationary oscillations that the phenomenon would be sim-

ple enough to allow the application of statistical methods to its study.

Since, however, the phenomenon is dynamical, all (apparent) knowledge

gained by a purely statistical treatment of the subject is defective and

may be discarded, or must at least be considered as being an insufficient

proof.

Let us examine the maps.

The departures for the decade of 1873-1882 give a map showing the

existence of a macropleion covering practically all the area of the United

States and extending most probably far north into Canada and south

over the West Indies. Negative departures’? are to be observed along

the Atlantic coast, in Boston, New York, Philadelphia and Wilmington,

and also in San Diego, Calif. The positive departures are highest in

Duluth, La Crosse, Chicago, Indianapolis, Cincinnati, Nashville and,

farther south, in Key West, where the departure is + 0.9 F. The highest

figures are + 1.3 in La Crosse and Cincinnati. ‘The macropleion has a

well marked crest extending NNW.-SSE.

During the following consecutive decades, this crest persists with a

striking tendency to assume a N.-S. direction and, at the same time, we

notice a slow displacement of the macropleion toward the south and the

more or less gradual development of a macromeion in the west.

A radical change in this nearly stationary situation occurs between the

decades 1877-1886 and 1878-1887. I reproduce the following four maps

1oThe figures —0.3 for Pittsburgh and Knoxville are considered as being evidently

wrong.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 47%

to illustrate the fact (Figs. 2-5). These maps show perfectly a circular

movement in a clock-wise direction. This displacement is gradual and

the inspection of the maps leaves no doubt about the dynamic character

of the climatic change. It also appears evident that the phenomenon is

confined to the North American continent: the macromeion takes the

place of the macropleion and both persist and stay on the continent: the

macropleion has been pushed over the West Indies and Mexico in order

to take the place of the macromeion over the western states, but has not

been pushed away, over the Atlantic, toward Europe or Africa.

Re 3

CIS

Bot

vay

aie

Sy aaa i awe

Ry ae Se

FIG. 2.—Macropleion. 1878—1887 Fic. 4.—Macromeion. 1880—1889

cs esatae

ae ee v7 7

ac yt i

R71 \e\, |

we Hea

Eeeaec at

are nae

ms yanenses

PRL Oe N !

as See a |

: phi as ,

SS, iG 3 a 4b '

ms '5 + os Nt

Fic. 8.—Macropleion. 1879-1888 Fic. 5.—Macromeion. 1881—1890

The maps of the following consecutive decades again show a more or

less stationary situation and a gradual development of the macromeion

toward the south: for 1883-1892 the departures are already negative in

the southern states and become more so for the decade 1885-1894.

Hence, a rotary movement of this macromeion, similar to that of the

macropleion of 1873-1882 and the following decades, would be expected.

This, however, is not the case. The displacement occurs, but in a pre-

cisely reversed direction. The western macropleion spreads out toward

the south, meets (1888-1897) a macropleion which progressively devel-

oped itself over the southern Atlantic states, and moves rapidly north.

48 ANNALS NEW YORK ACADEMY OF SCIENCES

From 1889-1898 until 1896-1905 we have once more a nearly station-

ary situation with a gradual and slow contra-clockwise pendulation, The

following maps (Figs. 6-9) will serve to illustrate the progressive change

which takes place.

Insisting once more upon the fact that, in many cases, the departures

utilized are most problematical and that the maps must be considered to

be very inaccurate, I cannot refrain from drawing some more conclusions

gained from the inspection of these maps.

Ww CD

Ai MI

ane

Fira. 6.—Macropleion. 1893-1902 Fic, 8.—Macropleion. 1895-1904

sac af Gis

SSCWEaE a

Fic. 7.—Macropleion. 1894-1903 Fig. 9.—Macropleion. 1896—1905

The following table (Table I) gives the highest and lowest departures

for each decade of years. The corresponding totals show the amplitudes

of the anamolies of temperature represented graphically on the ten-yearly

maps. The highest figure is 1°.7 F. The amplitude of the macrochronie

variation is therefore very small. In other words, as far as temperature

is concerned, the changes of climate are restricted to narrow limits.”

The smallest amplitude is 0.9 and not 0, as it ought to be, if we had to

deal with regular seesaw movements.

Jt is interesting to note that I have previously found a similar figure for Purope.

The departure maps for the decades of 1851-1900 (L’enchainement des variations ecli-

matiques, p. 38) show a highest amplitude of 1°.1 C.—=1°.98 F.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 49

TABLE I.—Hatreme departures

Highest and lowest

Decades departures Difference Mean

TSI SSI USNS PAS iis EAoa Dior Orroroo Cm rE e +1.3 —0.4 Ue iz +0.45

STA MSS Syncs raeiakene sic occk svelte ci oreitel ceria) cholenede +1.3 —0.4 Loe +0.45

STU S Aree er treet etanay a oie ools aauetarnees ehoieveys +1.2 —0.5 IEA +0.35

MS GOa lS Seotaetens: elevekerste ol cielo leaeiereie/ovevevell seuss crane +1.0 —0.4 4: +0.30

MS ese SS Omir nle rete teveuictet oro) shotar cick eieietel veces elshel ens +1.2 —0.4 AG +0.40

STS USO emetecacie sore: ores otters aaa cesvevlel shavel Grete: ste +0.8 —0.4 IGP +0.2

SHO USES xicvencis ciel cue aysiakevs shel sles vere etatey Siedsuscets +0.7 —0.7 1.4 1)

ASSO USS Oeicry ce teletere cis obeks wicual sche. | cis chet ones +0.6 —0.9 ake —0.15

SSMS IO Sy ec ter cst selel oveuee Sorelle serge vsvelisienats +0.5 —(0.9 1.4 —0.20

SSD 1 SOM Rk Malarecelcorores eau elelkel-a ole eral shevralel ete! ovate +0.5 = (9 1.4 —0.20

US SS— USO WAv i aevsyakeisieteerstarevesecs, she ists, fave a a6 wits e +0.6 —1.0 1.6 —0.20

MS SASTS ODA Cie ale iajo is ellevenst ons eens releleie:ers, el areis +0.5 —1.0 Tt —0.25

SSH USO AR aa are deere ons alel a corn Der eler ele sie alielepe +0.6 (1433 1.4 —Q.10

ME SG—USO OD). sicce cats rene oisis) sialon tevera-s:ssi Bvalesi ee +0.3 —0.7 AO —0.20

MSS USO Ole a iacclelcue ole: ue) oe ayes sl Oe ciara secs +0.3 —0.6 0.9 —0.15

MESS Salles Oita mhenetonctere evolve ei eleiel eta on tab evenele Ghekacie +0.5 —0.4 0.9 +0.05

SSO SOS ese rere tee revel nVieh oieorever ais ele elelere ate wie +0.7 —0.5 2 +0.10

US IU RUS OO Myeieh diel e cc cre chews ererehe orans Sve) ve casters +0.6 —0.6 Me 0.

MS Oi UG OO eewetor ser eveconstey stesso ei si.ceelet 8 ele eyaleuecds +1.0 —=(0)16 WAG +0.20

SO 2S Oil totetorereck cos sstevers aoe soc ielavtensvexSne ereMece. © +0.9 (6 Iota) +0.15

SOSA OD earenen sek oeceey oe aietinice te Fee sev okey Was ve els) brake +1.0 —0.6 1036 +0.20

ES OA OOS Aenstaic co sieaaal Seale sey secs a A idle es eee +1.1 —O.8 ie Y/ +0.15

MS OHO OA ae aor el crea yesusuckelo erence lailel ouenevedel Sake +0.7 —0.8 iba) —0.05

SOG DOS sate ists Bisco lense ate al et olaie wccvataetamehs ois +0.8 —0.7 SD +0.05

Now, if we take the column expressing the highest departures, or

crests of the macropleions, we notice a well-pronounced variation of

about nineteen years duration. The means of highest and lowest depar-

tures also display a difference of about nineteen years between the warm-

est decades.'”

It is interesting to note that a period of nineteen years was advocated

long ago by H. C. Russell’* and recently by William J. S. Lockyer.**

The figures of my table are too uncertain to serve as a strong argu-

ment in favor of Russell’s period. I give them simply to illustrate a

method of research which is highly recommendable.

To sum up the results obtained by the inspection of the maps, I will

say that the long-range variations of temperature of particular stations

in the United States are due to irregular pendulations of macropleions

and macromeions, that these pendulations are complicated by the exist-

ence of slight seesaw movements (or vibrations) which increase or de-

crease the departures, making the macropleions more or less accentuated,

and that, finally, the entire system of macropleions and macromeions

moves up and down. This last movement is shown on the maps by an

increase in size of the macropleions and a decrease of the macromeions

or vice versa. This is the real long-range variation. The decade of

12 The lustra means of the temperature observed in New York City demonstrate this

variation very clearly. (Am. Geogr. Soc. Bull., Vol. 45, p. 124. New York, 1913.)

18H, C. RUSSELL: ‘Meteorological periodicity’ (Journ. Roy. Soc. of N. S. W., 1876,

p. 151).

14 Solar Physics Committee. A discussion of Australian meteorology, p. 66. London,

1909,

50 ANNALS NEW YORK ACADEMY OF SCIENCES

1873-1882 is a typical example of a widely spread-out macropleion, while

the decade of 1883-1892 shows a predominant macromeion.

The next problem to be taken into consideration is whether the maxi-

mal development of macropleions occurs simultaneously on the different

continents.

I have already published the departure maps of the five decades from

1851-1900 for Europe,’ but I think that it would be useless to make

comparisons without the aid of consecutive maps. ‘Therefore it may be

that the increase in temperature is simultaneous on both sides of the

Atlantic or that, on the contrary, there are compensations,—it may also

be that there are correlations in the movements of the macropleions or

even pendulations of a higher order. I have to leave these questions

unsolved. They concern the last and most important of the three prob-

lems of long-range climatic variations mentioned at the beginning of

this discussion. I may venture to add that this is also the only problem

which remains to be solved, because the second problem concerning long-

range variations, mentioned above, does not harmonize with the dynam-

ical conception of climatic variations which must be admitted.

EUROPEAN TEMPERATURE Data For 1900-1909

It is really astonishing that after all the efforts which are made, all

over the world, to organize and maintain meteorological stations, mainly

for the purpose of collecting data, the actual results of the work which is

done are as inaccessible as they are.

It seems to be a very simple matter to take into consideration the

European temperature data for the years 1900-1909 in order to discuss

the results, but it is not so. I had in view the yearly means of these

years. One would think that in a town like New York City all the pub-

lications where these figures are recorded could be easily found. This is

a mistake. In order to have the necessary data I had to obtain them by

correspondence. I express therefore my thanks to the Directors of the

different meteorological institutions who helped me in my work by pro-

viding me with the necessary data.

In the following tables (Table II) I give the annual means in form

of departures from the means of the decade 1900-1909. All the figures

are degrees centigrade.

1% Op. cit., pp. 40-42.

TABLE IIl.—Z emperature data for European stations'

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE

1900 1901 1902 19038 1904 1905 1906 1907 1908 1909

Mean

GREAT BRITAIN

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TABLE II.—Temperature data for Huropean stations

1900 ee 1902 1908 1904 1905 1906 IU Bett) 1909

Mean

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TABLE II1.—Temperature data for European stations—Continued

ARCTOWSKI, CHANGES

1900 1901 ~- 1902 1908 1B0¢ 1905 1906 1907 1908 1909

Mean

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ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 61

The records of France, Spain, Portugal, Italy, Servia, Turkey and

Greece have not been taken into consideration. For Russia, Austria,

Belgium, Holland and Switzerland I had only a small selection of data.

For Russia, in particular, the number of utilized stations is absolutely

insufficient.16 For Great Britain I have taken the district means. In

reality, then, I have taken into consideration only Scandinavia and Cen-

tral Europe, and European Russia simply for the sake of orientation.

It would seem that the figures of more than four hundred stations

ought to give a very accurate idea of the variations of temperature which

occurred during 1900-1909 in Central Europe.

This is true only to a certain extent.

First of all there are some local complications due to orographical con-

ditions To try to discuss these complications would lead me too far

afield and would necessitate still more data.

I had in view simply to get a general idea of the geographical distribu-

tion of the annual departures of temperature and, for that purpose, I had

just enough data.

The area covered by Scandinavia and Central Europe is absolutely in-

sufficient to give the necessary maps for a clear understanding of the

climatic variations which take place. Europe is but a fragment of an

immense continent: the old world of Asia, Africa and Europe, and the

variations of temperature which occur in Central Europe evidently de-

pend on those which occur in Asia, in the Arctic regions, on the Atlantic

and perhaps also of those which occur in Africa, in Equatorial Africa

and the Sahara in particular. Central Europe is probably the least favor-

able spot on the earth’s surface to be taken into consideration for the

study of climatic variations. There, the variations are far too compli-

cated to be understood easily. It would have been a great advantage to

me, if I had had the data of all the Russian stations, those of Siberia and

Turkestan in particular, and also the Indian data; but then I would

have had to face such a number of new problems that it would have been

quite impossible to stop the research work in order to write down the

results obtained.

The ten European departure maps which I publish now (Figs. 12-21)

are simply first material for further researches. These maps are most

suggestive for many special investigations. In order to advance, how-

ever, I will avoid details as much as possible and will pass at once to the

main question: the cause of pleionian variations.

1¢J7t is my intention to study more in detail the variations of temperature which oc-

curred during the years 1900-1909 in Poland, the Russian Empire and India as soon as

circumstances permit.

62 ANNALS NEW -YORK ACADEMY OF SCIENCES

Besides the Scandinavian countries, for which I had the complete

record of observations, I had at my disposal the monthly means of tem-

perature of Bucarest, Kazan, Warsaw, Odessa, Aachen, and Geneva. I

made consecutive twelve monthly totals for these stations and also for

Bodo, Sydvaranger, Haparanda, and Vestervig. On the following dia-

grams (Figs. 10 and 11) I reproduce these totals graphically, together

with the curve of Arequipa, which will serve as a type of the direct solar

variation in equatorial regions.

Bucarest.

Odessa.

Warsaw.

Kazan.

Arequi pr:

0g;

Fic. 10.—Ourves of the consecutive means at Bucharest, Odessa, Warsaw, Kazan and

Arequipa

The striking fact which is exhibited on these curves is that the varia-

tions of the European regions having a frankly continental climate are

radically different from those which lie under the prevalent influence of

the Atlantic. The curve of Kazan exhibits tendencies of increase of

temperature followed by tendencies of decrease in regular successions,

a variation repeating itself independently of the seasons of the year, just

as in Arequipa. In Bucarest and in Warsaw we have also the typical

pleionian variation. The curve of Aachen, on the contrary, is absolutely

different. There we have small ups and downs entirely disfiguring the

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 63

pleionian curve. The Aachen curve is characterized by brachyechronic

variations of small amplitude.

In northwestern Europe, then, the brachypleions must have a pre-

dominant importance, whereas they do not affect eastern Hurope very

greatly. The curves of the Scandinavian stations, on the other hand,

belong to a mixed type of pleions and brachypleions. Here we may have

Geneva.

Aachen.

Yestervie.

Bodo.

4 aparanda

Fie. 11.—Consecutive temperature curves at Geneva, Aachen, Vestervig, Bodo,

Haparanda and Sydvaranger

a succession of several years during which the changes of temperature

will be slow and great, as in Russia, followed by a succession of years of

shorter and more irregular changes entirely different from those of Russia.

It would seem that there are pleionian and brachypleionian areas and

that the border between them may temporarily belong to one area or the

other. In reality, however, things are more complicated because the

pleionian and brachypleionian variations are coexistent over more or less

large areas. The comparison of the curves shows this very plainly.

64 ANNALS NEW YORK ACADEMY OF SCIENCES

If we now compare more closely the curves of Kazan, Warsaw, and

Bucarest with the Arequipa curve, we notice sufficient similarities to

grant that the primary cause of the Russian variations is most probably

the same as that which produces the equatorial variations. The main

cause of the complications in the geographical distribution of the excess

and deficiency of temperature has to be ascribed to the perturbations of

atmospheric circulation and transport of water vapor. We have to admit

that if the value of the solar radiation changes, the temperature at the

earth’s surface must change; but the total atmospheric pressure remains

the same. Consequently, a rise or fall of temperature must produce

abnormal changes in the distribution of atmospheric pressure. ‘These

changes will affect the winds, the rainfall, and also the temperature.

The normal, or let us say the Arequipa, variation of temperature must

therefore undergo, in different regions, all sorts of modifications due to

the local conditions of atmospheric circulation.

This fact explains the coexistence, and mutual dependence, of pleions

and antipleions and explains also, to a certain extent, the persistence and

more or less progressive displacement of the pleions from one region to

another.

On the other hand, some, at least, of the brachypleions may be con-

sidered as peripheric trepidations of the pleions.

At present this interpretation is evidently but a simple working hy-

pothesis for investigations yet to be made. It will, however, be suffi-

cient to compare the curves of Aachen and the Scandinavian stations

with those of figures 59 and 60 to arrive immediately at the conclusion

that the brachypleionian oscillations are not at all a particularity char-

acterizing the purely maritime climate of oceanic islands, as at first one

would have been inclined to think.

The temperature scale not being indicated on the diagrams (Figs.

10 and 11) I give in the following table (Table III) the values of the

highest and lowest consecutive means and their differences. These fig-

ures are °C. It would have meant too much work to reduce all the fig-

ures utilized to draw the curves into mean temperatures and into °C.

The utilized figures are simply totals of twelve monthly means. In the

ease of °C. I added fifty to all figures in order to avoid the negative

values of the winter months. For totals of °F. the figures of course give

an apparently greater amplitude of variation to the curves. The pre-

ceding table will serve to make comparisons possible in case anyone would

like to examine the amplitudes of individual crests. For my present

purpose such comparisons are unnecessary.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 65

TABLE ITI.—E.treme values of consecutive means

Highest Lowest Drees

(STONE) Be clot 0 COO Cn 6 COG IORCRDIDIO Te oar 5 8.4 L9

PACH OTe ca etal oyreactareraialieweusitowenclsic tesco! s/c) ose aha uneuer onsitalie 5 8.2 a)

WMESCOIVS ei ctaicics 6 ce) cual anerster ere ice rclie =) s)-sp 3) initer oeieneire tet lerle lolee xe 6.1 Die

SOO epee fence ey onr eae ore eueitelle nila Sle oviel.s: wlesle topes erorctarat : 29 2.3

Sydvaranger —3 -o 4.3

EVA PAT ANG (ere t6 0/010) e)= «1= ele) ee) 1s = = = : 5.566 2. —2.3 es

SICH EOS Urata eee ha niece eh areas tener hskeriskete: @usi@rersiensyenere .6 9.0 2.6

GES Sar ory cal seal cae av cue faleitevie, ay sh nclovsrceoun (6 9p Bi ae'e ene eibas lorie 8.4 So

VESEY? 36.6 di Oo Gc Olo SiDoinItA Gcheae OF alomioralo chen 6.4 229)

TSEAANIRY . Se SIERO. CROCE SAIS Ck CREM n ERR Rete 1.4 4.6

Passing now to the description of the maps, we will immediately

realize the usefulness of the curves of consecutive means, because these

curves eliminate the possibility of hazardous speculations about the dis-

placement of the pleions from one year to another. Instead of such

superficial considerations, we will find the way to study systematically

the progressive transformation of the maps, a task which I cannot under-

take at present not having the monthly means for all, or at least a large

number of stations.

The map giving the distribution of the departures for 1900 (Fig. 12)

is practically identical with the map of the same year I have traced,

utilizing the departures from the means of 1891-1900." This demon-

strates very clearly the fact that annual departures from ten yearly

means serve perfectly to indicate the position and shape of pleions and

antipleions.

On the present map the quasinormal line crosses Denmark, Southern

Sweden, Curland, and forms a curve across Russia toward the Azof Sea.

North and east of this line the departures are negative, south of it they

are positive. The antipleion forms an immense wave with two centers

of lowest values, one in Scandinavia, the other in Eastern Russia. In

Sweden the greatest negative departure occurs at Quickjock and is

— 2.0 C. The Russian data do not permit of locating the eastern center

of the antipleion exactly. In Kazan the departure is —1.0. The

highest values of the pleion are + 1.5, in Hungary. The pleion is

broken up in central Europe by an area of low values. In southern

Germany and Bohemia, the departures are below + 0.5 and decrease

to 0. along a line extending from the Belgian frontier into Bavaria.

The map of 1901 (Fig. 13) shows a radical change in the distribu-

tion of temperature. Where we had a negative wave we now have a

positive wave. The pleionian departures are + 1.2 in Swedish Lapland

and + 1.3 in southern Russia. The quasinormal line goes from Great

Britain across Germany and Austria towards Rumania. The lowest

departures of the antipleion are — 0.7 in Erfurt and — 0.8 in Gottschee,

in Krain.

Op: (Ctts, py 121

66 ANNALS NEW YORK ACADEMY OF SCIENCES

4 \

——~|

AS)

Fic. 13.—Temperature departures for the year 1901

. orto

~2e5

oye

Fic. 15.—Temperature departures for the year 1903

68 ANNALS NEW YORK ACADEMY OF SCIENCES

Naturally one asks whether the antipleion of 1900 went down or the

pleion went up. The consecutive curves will give some indication about

the displacement which took place: The pleionian crest passed Kasan at

the consecutive mean: Sept. 1900-Aug. 1901. In Haparanda, Bodo

and Sydvaranger the crest occurs at the mean of Noy. 1900—Oct. 1901.

In Vestervig and Aachen, Feb. 1901—March 1902.

We must admit therefore that, most prdébably, the displacement went

from northeast to southwest, but the map shows the existence of an

antipleion over the White Sea. Moreover, in 1901, the consecutive curve

of Kazan is on the descent. The same is true in northern Scandinavia.

If we consider the dates of the occurrence of the minimum, we find:

Sydvaranger, Haparanda, Bod6é, November, 1901—October, 1902; Kazan,

1902; Vestervig, Warsaw, Bucarest, February, 1902—January, 1903;

Geneva, May, 1902—April, 1903. There is, therefore, a progressive in-

vasion of a negative wave coming from the White Sea and spreading out

towards the southwest and south. The map of 1902 shows plainly the

importance of this antipleion.

This characteristic antipleion, with a departure of — 3.1 at its center in

Mezen, follows closely the first depression of Arequipa. Therefore, a de-

tailed study of the meteorological phenomena of 1902 would be most

instructive if one took, besides the European data, those of Asiatic Russia

and India. The distribution of the equideparture lines on the map (Fig.

14) shows plainly the dynamical character of the phenomenon.

It would not be very difficult to find out how this antipleion invaded

Kurope and the reason why could be traced as well, and correlated with

the equatorial variation of temperature.

The map (Fig. 15) of the departures for 1903 is just as interesting as

the map of 1902. There is an important rise of temperature over all the

area with the exception of southwestern Europe, Ireland and Scotland.

Now there is a pleion centered over Russia, where the departures are

+ 1.5 in Pernau, Vologda and Vychnyi Volotchek.

What became of the antipleion of 1902? Did it go towards the At-

lantic and the south, or was there a rise of temperature in situ without

any displacement ?

The consecutive curve of Geneva (Fig. 11) shows that the antipleion

of 1902 certainly did not cross Switzerland to go south; but the curves

of Sydvaranger and Haparanda are very steep immediately after 1902,

the curve of Warsaw (Fig. 10) shows a regular and progressive ascent

from 1902 until 1903, while the curve of Bucarest, on the contrary,

shows a slow ascent followed by a very much faster increase of tempera-

ture towards the end, and there the values remain high till the mean of

AROCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 69

1904

Fic. 16.—Temperature departures for the year 1904

Fia. 17.—Temperature departures for the year 1905

70 ANNALS NEW YORK ACADEMY OF SCIENCES

Fic. 19.—Temperature departures for the year 1907

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE Yt

September, 1903—August, 1904. Consequently, consecutive maps would

show that the formation of the pleion began in the north and extended

progressively south or southeast.

The map of 1904 (Fig. 16) shows a distribution of the equideparture

lines similar, to a certain extent, to that of 1901; but the sign of the

departures is reversed, since we have now an antipleion where we had a

pleion in 1901. The consecutive curves are again a great help towards

the understanding of what happened. lf we consider this depression

of temperature as being due to the same cause as that of Arequipa, we

may say that in Kazan the reaction is felt first, then in Warsaw and.

finally in Bucarest, where it is very much retarded.

In Scandinavia the phenomenon appears to be more complicated.

There we have two distinct depressions. One is coincident with that of

Arequipa, as the curve of Vesterwig shows, and the other is greatly re-

tarded. It may be that the second depression of Haparanda and Sydva-

ranger is due to a propagation of the antipleion first formed in Russia.

The map of 1905 (Fig. 17), if considered from the same point of

view, represents the formation of a pleion and that of 1906 shows the

same pleion after the maximum of its development.

The most important crests on the curves of Kazan and Bucarest occur

between 1905 and 1906 and correspond to an Arequipa crest. In War-

saw we notice fluctuations; the same in Scandinavia, where they are even

more pronounced. This pleion must have been Asiatic.

In 1907 (Fig. 19), there are residual pleions over Scandinavia and

central Europe and an antipleion over Russia.

Between 1907 and 1908 the curves of Warsaw, Bucarest and Geneva

show the Arequipa crest.

This fact demonstrates that the Russian antipleion did not spread out

progressively over central Europe, as a comparison of the maps of 1907

and 1908 seems to indicate. On the contrary, an important interruption

occurred, during which a brachypleion (corresponding to the Arequipa

crest of 1907-1908) came from the south and invaded southern and west-

ern Europe without affecting the Russian antipleion. Finally, this Rus-

sian antipleion of 1908 went west in 1909 (Figs. 20 and 21). The con-

secutive curves, the curve of Geneva in particular, leave no doubt about

this fact.

The main result gained by the study of the maps is that, during the

years 1900 to 1909, the pleions and antipleions did not move from the

Atlantic across Europe towards Asia. On the contrary, the displace-

ment was from the northeast towards the southwest, or from the east

towards the west. Moreover, these displacements did not cross the areas

ANNALS NEW YORK ACADEMY OF SOIENCES

Fic. 21.—Temperature departures for the year 1909

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 73

of maritime climate.. One may say, therefore, that the big pleionian

variations of Europe are a purely continental and, perhaps, Arctic

phenomenon.

It would be premature to attach any importance to the locations of

origin of particular pleions. The areas where they are formed, in situ,

are probably not always the same. Besides, the question whether a pleion

is of an Asiatic or arctic origin has no importance for the present, simply

because it would be absolutely premature to discuss the reasons why,

under the influence of a temporary increase of solar radiation, one loca-

tion of the polar or temperate regions is more favored than others.

It is evident that a temporary increase of energy radiated to the earth’s

surface, during, let us say, three months in succession, will not directly

influence the temperature of the arctic regions if if occurs during the

winter months of the northern hemisphere, whereas the antarctic regions

will be greatly influenced.

The question of the formation and development of pleions, outside the

equatorial regions, must be studied together with the seasonal changes

of atmospheric pressure and the temporary alterations of. atmospheric

circulation, nebulosity, rainfall, ete. I intend to make such a study for

particular pleions and especially for brachypleions. The fact, however,

that in Russia there are some striking coincidences between the forma-

tion of pleions and the crests of the Arequipa curve is a most convincing

proof of a common cosmical cause of these variations.

AMERICAN TEMPERATURE Data For 1900-1909.

Since the equatorial or Arequipa variations of temperature can be ob-

served not only in Russia but also along the Atlantic coast of the United

States, in New York in particular,'* it was really fascinating to follow

more Closely the changes in the distribution of temperature which oc-

curred simultaneously in different regions of the North American con-

tinent. Here, it was possible to follow the phenomenon from ocean to

ovean, over a much more extensive area than that of central Europe, and,

this area being more isolated, it is self-evident that more definite results

were obtainable.

A research, apparently similar to mine, was made long ago by Helm

Clayton.1® It was only after my investigations were nearly completed

that I noticed the fact and Clayton’s writings have therefore not at all

influenced my work. Clayton studied the monthly departure maps pub-

18H. ARCTOWSKI: “On some climatic changes recorded In New York City.” Bull.

Amer. Geogr. Soc., Vol. 45, p. 117. New York, 1913.

1H. HELM CLAYTON: “Weather changes of long period.” Amer. Meteor. Journ., Vol.

2, p. 126. Detroit, 1885.

V4 ANNALS NEW YORK ACADEMY OF SCIENCES

lished in the Monthly Weather Review of 1884 and 1885, and for the

sake of comparison I give his conclusions below.*® The results I have

obtained so far are so different from those of Helm Clayton that it is

perhaps necessary to insist once more upon the fact that my maps are

annual departure maps, whereas the maps utilized by him were monthly

departure maps. Even in the case of monthly maps of temperature,

however, Clayton’s generalizations must be Considered as simply plausible

hypotheses, which may disagree with the observed facts. The departure

maps for the months from August to November, 1912 (see Monthly

Weather Review), will serve as an example.

The method of research I have adopted is evidently the same as that

of Clayton** and the pleionian variation, of equatorial regions in par-

ticular, is certainly the same phenomenon as the meteorological cycle

of twenty-five months’ duration discovered by Clayton,** or the longer

cycle, of about three years, advocated by Lockyer and others.

Though the method of using consecutive means, and tracing departure

maps, has already been used long ago, it has not yet been applied to the

scientific study of climatic variations in a sufficiently extensive and

careful way to lead to the results of general interest and practical ap-

plication which we might expect to obtain.

Before entering into the details of the description of the departure

maps of the years 1900 to 1909, I will take into consideration the geo-

graphical repartition of the range of variation of the annual means of

temperature.

On Bigelow’s tables** I have formed the differences between the high-

01, There are areas of barometric depression, and elevation, which occupy weeks

and months in their movements across the continent from West to Fast.

“2. There exist, Independent of the movements of areas of barometric depression, and

elevation, numerous seesaw oscillations in. the pressure which have been given the name

of surges.

“3. In front of and to the south of areas of barometric depression of slow movement

and long duration, as in those of rapid movement and short duration, the temperature

is above the normal; and below the normal north of them and in their rear which is

usually the front of barometric elevations. In front of, and to the south of, areas of

barometric elevation of long period, as in those of short period, the temperature is below

the normal, and above north of them and in their rear which is usually the front of

depressions, (In winter the area of warmth approaches and usually includes the area

of lowest pressure, and the area of cold approaches and usually includes the area of

highest pressure; in summer, vice versa.)

“4, In front of, and within, barometric depressions of long period, as in those of

short, the rainfall is above the normal, and below. in their rear. In front of, and

within, barometric elevations of long period, as in those of short, the general tendency

is towards fair and clear weather with deficient rainfall.”

71 HENRY HELM CLAYTON: ‘“‘A proposed new method of weather forecasting by analysis

of atmospheric conditions into waves of different lengths... Monthly Weather Review,

1907, p. 161. See also:

HENRY GAWTHROP: Temperature curves (Jbid., p. 576).

*2 American Meteorological Journal, Vol. 1, p. 130. 1884.

23'On: cit;, Bull: S:

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE %5

est and lowest annual means. The geographical distribution of these

figures is most interesting. The highest differences are those of Bis-

marck, Duluth, St. Paul and Marquette. The figures are respectively

9°.8, 9°.7, 9°.5, and 9°.4 F. In North Dakota and the Lake Superior

region the range of possible variation of the annual means is therefore

above 9°F. From that region, the values diminish progressively towards

the east, south and west. The line limiting the region where the differ-

ences are above 5° goes from Portland, Ore., towards Salt Lake City,

North Platte, Hannibal, Lynchburg and from there northeast, along the

Atlantic coast. The difference 7°.2 for Portland, Me., is too high. The

series of observations taken in Portland, Me., is evidently not homo-

geneous. The values of 5°.5 for Los Angeles, 5°.8 for El Paso and

San Antonio are also probably too high, since the line of 4° goes from

Eureka southward over Sacramento toward San Diego, then eastward

towards Little Rock, Memphis, Atlanta and Wilmington.

The lowest value, 3°.1 for San Francisco, and the value 2°.8 for the

shorter series of observations of Corpus Christi and Jupiter, are not very

much higher than the differences 2°.1 and 2°.6 of the pleionian crests

and antipleionian depressions of the consecutive curves of Arequipa and

Bulawayo. It follows that if, all over the United States, the varia-

tions are primarily due to pleions, having the same cause as the equa-

torial pleions, the phenomenon would be four times more pronounced

at the center of the North American continent—in Winnipeg, let us

say—than under the equator. Of course, in the case of the brachypleions,

the difference would probably be very much greater, and if the results

obtained from the study of the interdiurnal mean variabilities of temper-

ature? are taken into account we must be impressed by the similarity

of the results obtained. Evidently, the continentality must have the |

same exaggerating effect on climatic variations that it has on the cold

and warm waves characterizing the changes of weather.

I will pass now to the study of the annual departure maps.

The figures utilized have been taken from the Annual Reports of the

Weather Bureau and those of the Canadian stations were copied from

the Summaries of the Monthly Weather Review. In Table IV, I repro-

duce the means of the decade 1900-1909 and the annual departures from

these means for all the utilized stations. These figures were inscribed on

maps and equideparture lines drawn. The ten maps thus obtained are

reproduced as figures 22-31.

J. HANN: “Untersuchungen uber die Veriinderlichkeit der Tagestemperatur.”’ Si{tz:

Math. Nat. Cl. Acad. Wiss. Wien, Vol. 71, II, p. 571. Wien, 1875.

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Bilele\\e'<e e (e,1e)\e).9) (8) 0) e1.e (0. ¢,\63 8 u0)¢Lele) Selle RIV ‘IOUIOS UO

Slaps sc) le lelele) alsrene, FIDIOD DIE BOO ROO DOOD LETT AT ‘QTIQOW

see ee DOO, OOOO OOOO OOO TARA ‘sTjodvouulyy

evells| sue) e lleus) =) 6 SPORT OPOID OPO" OF Ty HY ‘QONBATIA

0 ae lelere:s Siaiiei okelehe (ere teeiere cae male TT (TAT "AUD SOTW

eevee ojo (eles. euskeseheueile) eis) ohekeneiedes chm SS TIA ‘UBIPIOTV

CO eC) Gets ORES TOUCHE OO iG, ‘stud may

ehelelelulene DODO CEO CRO OT OOOO BAT), ‘aqjenbaeyyy

cl alaratev ete! ate edsialsdalleiellolalacal ener snaiansial PDT OEE A) ‘MOOR

Selahe al exelene S60 .0).0,¢).6/ 3) e's es) ais) aaevefale BA ‘sanqyqoud'y

Orme yor. O VOT @) 8 (0) 6Le70 1s ee evens DOTS | ‘OT[TASTNO'T

eleveieleiers DIDO TIO D101 O.010'0 010/95) 775) ‘sojasuy soy

@/\¢ 0).0/.0) © v6) @)60) ¢) es) ele) e)6)e)els)e)alele ‘yay ‘yooy evIT

606T-006L apnoap ayy of (YZ) Suna aungnsadmaT— AT TAY,

TABLE IV.—Temperature means (°F.) for the decade 1900-1909, etc_—Continued

ARCTOWSKI, CHANGES IN DISTRIBUTION OF

1906 1907 1908 are,

1905

190

1902

1900 1901

Mean

NOAA ANGIOHA MAS & AS al ot

Spa ar vanes nano 1

Wl setae ty ieetee tl ate

TA AIOE OAD AV A IB WS HAO DH 19 HDD PDOOMO

Pe eee en ees es

PtHIF IF IHL L+H 1 ++t++ 1 t4+4444-+4 1 1

ADOIOMAAMDOC DWDNOSNADARKHHARHARAOnAHHOWM

SONSCHOMHOSCSCONSCSMOSCSOSSOonSSSonSCSoOHS

PT It++I+1 1 L+T+T 1 ttH4 1+ 14+ 14441

2S P10 110 t= HO 169 A600. S AO 09. C0 4G R= 00 CD 41

DSSSHSSSsHsSssssesHsHss SSHSSSS

I+++1+1+ FIFF+EI +1447 141444

TAD C9 VOD C19 19 SO SHON NCO AI AT 1D OD HID OD IO HOI OCIOMA

SHASCSnSSSSCOn SOSH OSOHnHOSSSonHHOHOSOS

LW SRiSSel dl set ISS ed se

Yer) CYC EMS CO = S001 001 6 sH 6 Od

so al

FIN HISD O ID 19. OOS PPD C9 19 b= MEO IC CO 2G 1 HCD 1 C9 T1109

SdHHSoSsoSSonSH HOSHSOHOHSHHSOnHOS

+4+4+4+ 1 TFE++ IFT FHH4+1 1 1447 14144

HHOoons ID ID AI SDH AOD EDO NW AI ODI HDA ID

SNNNSOSHOORHHOHOHHHHOOHHNOHHHOS

FAFHEFTTPEE HTT HT Ht4+$ ttt t+

LINAC dh aha le MAcelejerl ia Seo Saeed) GO SO SHI G0 169. CO NI B= Aro CO

OOtnoOns 3040 DOROAOKLHNSOHS SHOISHOOIR

DiathADSotsrist+n Sosa NaN eo HO 1D 19 SO Ht~

Tere ese VE Citric, siecenctet entree crorcriete-ic.o Gaare

BNGUSK ye OMITO oresstniite.c: o's Gisieteiele vero siete le leveveveyie

FUEL AIT CIS COs Bil Beara cy ciateveuera crcuelsliewe lyreerc Gaerne

Ebel diva, IeOeiOy I,m ogoouououeboUapnodd

ARASH ODISDO mm GH ate cpccunicrstensicis sts vete. ous ore 0

PND TORO aC allieeitarctencieteg cvaiceayetchete fore cneneWWrererel's

itmleaIKen Ci ym Nees ore ccenee ove iceegsle@ sehowes

PIMPAMIONML OMEN yet nels res cachetelicsielarer sinless is ae

omen ee TIN rey one avietrancical er cusieie: etela.s) cuanane tallelieriel

. re

Z. —

eEa

Bas

Si eaigs

qs 5

Baa

WITTE TLIC COMBDING Viavsotetdenelelcuexcncreie) inte ste) eyeloneie ans

SVAUI INT AAU Zigitecceni ue vekvcaeuchenelenaions

SAICHAIMEN COM Galinc.s halen stra cisieicle siclevers le sells s) eps ene

SMI UILS ped VI Olemettavarravrel outa cicet ericsiictiacs (oie vonsue citer‘eivaris« ce

SS GAGE a VVISS ewes tetepewcreitctie ederene: cies veneers essere wee

NUREVEDORiwellad cree tests cuca © ore @e 4 eo alee

LOUK Cl wlONWE et Meme reside sietets ete os, st eclseafaliet's gus

WDOKAMEG RVs lkweccteietate incieusoni weiss aie leek +

POT TRV CLM Seren teave tee ronsicne eucvcva cdot ay ostepchie ve eels

SS DUM STEM O eawencs cn crcke opele etree one, sienehsre ei ebe cae

PAGO AVN Dede seeds. sense tonciton suet enero aie ss anenene

PUTED INT EPMO) rer eratrentaceite pevetcoll chal erate eo a: corelceieicenceseher nes ievlens

MOLCCOSEO Di Ofer rere touaketede rece sun eilisiace ierenes 6 a.0 ener

MMO WE Ke NS epee awe; ete) sive neha hen ees@sici'eine.e ede efel evecare

WaLentine ING vctrsirnreclsnoleiererens sce) sieve were 8 ene

WACK Sip Ur oeMiS Siri weneneite) selene isnensuehs) oeveke eeiic, sie lece

WES TV eTON SIDS Ge raicrewevereverene) Greve eveneleve: cee gue slsve

WH Chita CaM Ss ccveresusuclrensusl ole @eslene gveweys deus sneneve se

\wallhecnhysvoya IN, Oo agoqooubunuopoood

)

SS)

TEMPERATURE

American

the

Review and the figures for

_—

=i.

es]

ea)

Weather

Ss.

1 For the Canadian Stations the annual means have been copied from the

Stations have been taken from the Annual Reports of the U.

80 ANNALS NEW YORK ACADEMY OF SCIENCES

Fic. 22.—Temperature departures for the year 1900

‘

Sy of

en cemoen oan «,

- ee

Fic, 23.—Temperature departures for the year 1901

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 81

‘

mise

‘

Fic. 24.—Temperature departures for the year 1902

A :

“-<<" -

eT s

eee lS

== .

pee ae

---"

for the year 1908

Fic. 25.—Temperature departures

82 ANNALS NEW YORK ACADEMY OF SCIENCES

Leaving for the present the curves of consecutive means and the con-

secutive maps, which will serve later for a better comprehension of the

dynamic phenomenon of the transformation of one map into another, I

will describe these annual departure maps and formulate questions and

suppositions, just as I did in my former research into the variations of

temperature during the years 1891-1900. °*

The map for 1900 (Fig. 22) is peculiar in that the departures are

above the average all over the States. The quasinormal line follows

the Gulf of Mexico from Corpus Christi over New Orleans towards

Tampa, Fla. At Key West the departure is —0°.5 F. Porto Rico be-

longs to the pleionian area. In Bermuda the mean equals the ten-yearly

mean. In the northeast there are negative departures in New Brunswick.

The pleion has two centers, one in South Dakota, the other in Penn-

sylvania. The highest departures are + 2°.2 in Valentine, Neb., and

+2°.4 in Harrisburg, Pa. The equideparture lines of + 1°.5, sur-

rounding these centers, are separated by a strip of lower departures ex-

tending from Lake Huron towards Oklahoma.*°

The map of 1901 shows a pleion in the west, an antipleion in the east

and another pleion having its center south or southeast of Nova Scotia.

In Newfoundland the departure is + 0°.8 C.—-+ 1°.4 F. at St. Johns.

It is above + 2° in Nova Scotia. The highest departures of the western

pleion are + 2°.2 (Bismarck, N. Dak., and Pierre, S. Dak.), whereas the

highest departure in 1900 was + 2°.8. The center of the antipleion is

at Macon, where the departure is — 2°.0. Comparing the maps (Figs.

22 and 23), it looks as if the antipleion came from the Gulf of Mexico

pushing the eastern center of the pleion of 1900 from Pennsylvania over

Nova Scotia and New Foundland, while the western center remained

stationary.

The map of 1902 (Fig. 24) is very different from that of 1901. The

positive as well as negative departures are smaller; the contrasts between

the pleions and antipleions are less accentuated than in 1901. ‘The out-

lines of the areas affected by positive and negative departures are com-

plicated. The map gives the impression of representing intercrossing

waves. It is as if the western pleion of 1901 had been cut in two and

as if the two centers had been moved apart: the center of South Dakota

northwesterly into Manitoba and the center of Utah southeasterly to-

wards Texas. An antipleion separates these pleious and, perpendicularly

to this furrow, a ridge of positive departures extends from Louisiana to

Nova Scotia. The antipleion of the west also has the shape of a wave.

2% The departure of +0°.2 at Chicago is evidently incorrect. The departure —0°.1

of Fresno, Calif., 1s likewise in contradiction with the other Californian data.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 83.

Fic. 26.—Temperature departures for the year 1904

Fig. 27.—Temperature departures for the year 1905

84 ANNALS NEW YORK ACADEMY OF SCIENCES

Fic. 28.—Temperature departures for the year 1906

: —s

Fic. 29.—Temperature departures for the year 1907

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE — 85

The question is whether this antipleion, extending from Alberta to Lower

California, came from the Pacific or is the southeastern antipleion of 1901

which moved across the States.

Nineteen hundred and three is a year of a predominant antipleion

covering nearly the entire area of the United States and extending north

and south into Canada and Mexico (Fig. 25). The most negative de-

partures are — 2°.4 at Grand Junction and — 2°.8 at San Antonio.

This antipleion has a third center in South Dakota and resembles in

shape that of the preceding year. A close inspection of the maps gives

the impression of a contra-clockwise movement.

If this hypothesis is justified, it must be admitted that the map of

1904 (Fig. 26) expresses the result of the continuation of this circular

displacement. In 1904, the center of the antipleion is in the northeast

of Lake Huron, with a departure of —3°.4 at Parry Sound. In the

west, on the contrary, there is now a pleion which, in this hypothesis,

would also have traveled contra-clockwise, from Ontario towards Idaho.

The western pleion has two centers with + 1°.9 departures at Helena,

Mont., and Independence, Calif. The map displays a very accentuated

contrast between the temperatures in the west and in the east and is

perfectly typical.

In 1905 (Fig. 27%), we have again negative departures all over the

States with the exception of Florida, California and parts of Washington,

Montana and North Dakota. In Alberta, there is a pleion with de-

partures as high as + 2°.9 (Battleford) and the same pleion extends over

the Pacific, the departures along the coast being + 0°.5 in Port Crescent,

Wash., and + 0°.8 in Eureka, Calif. In 1904 the departure was + 0°.1

in Bermuda, now it is + 0°.6 and it is this Atlantic pleion which extends

from Bermuda over Florida towards the Gulf of Mexico. It seems that

the change of the map of 1904 into that of 1905 was due to a displace-

ment of the antipleion from northeast towards the southwest, accom-

panying a displacement of the pleion from the west towards the north.

The movement was contrary to that of the preceding year, both the pleion

and antipleion remained on the continent and traveled around in the

same direction as the hands of a clock.

The year 1906 shows a continuation of this movement, at least as far

as the pleion is concerned (Fig. 28).

In 1907, on the contrary, the conditions are so very different from

those of 1906 that it is absolutely impossible to make any statement about

the displacements which took place between these two years. The map

of 1907 (Fig. 29) is precisely the reverse of that of 1906. Where there

was an antipleion there is now a pleion and vice versa. The disposition

86 ANNALS NEW YORK ACADEMY OF SCIENCES

- sd vie

<= ment {

Fic. 30.—Temperature departures for the year 1908

¢ ee

ee 1

. —, 4

\ vena, ?

ow, ‘

Cee, SR ies

worm oe

K a =>

= »

--r--

Fic. 31.—Temperature departures for the year 1909

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 8Y

of the equideparture curves is the same. A seesaw movement would ex-

plain the transformation ; but, as will be seen later, such an explanation

is not satisfactory.

The map of 1908 (Fig. 30) indicates a simple displacement of the

pleion towards the north. The shape of the pleion remained practically

the same and in the west an antipleionian wave, following the movement,

advanced over the continent. ‘The pleion has two crests, one going from

Alberta towards Kentucky, with the departures of + 2°.6 in Calgary,

+ 2°.1 in Medicine Hat, + 1°.9 in Bismarck, Minneapolis and Cincin-

nati, and a second wave following a perpendicular direction along the

Atlantic coast in the New England States (+ 1°.6 in Boston and New

Haven). Curiously enough, farther south, a depression in the pleion is

noticeable, the departure being + 0°.5 at Richmond, Raleigh and Char-

lotte, and only + 0°.3 in Lynchburg. On the Atlantic there is an anti-

pleion, the quasinormal line going from Jupiter, Fla., towards Halifax.

In Bermuda, the departure is — 0°.9.

Finally, the map of 1909 (Fig. 31) shows the disappearance of the

northwestern crest of the pleion under the influence of the advancing

antipleion, whose two distinct centers moved from Eureka towards Battle-

ford and from Independence toward Valentine. The pleion of 1908 has

been reduced to a wave extending from Nova Scotia towards Texas. The

most positive departures are + 1°.1 in Sydney, Grand Manan and Char-

lottetown, and + 1°.7 in Fort Worth, Tex.

To gain a more precise knowledge of the displacements of the pleions

and antipleions, which took place during the years 1900-1909, I made

consecutive maps and consecutive curves. I will examine separately the

results gained by the study of the curves and of the maps.

CoNSECUTIVE MApPs

The annual departures of 175 stations were utilized to draw the maps

I have just described. To obtain similar consecutive maps would have

involved a great amount of purely clerical work. I simplified the task

by omitting the Canadian data and taking only the means of the twenty-

one districts into which the United States are divided in the columns of

data published in the “Monthly Weather Review.” I copied the monthly

means for the years 1900-1909 for these districts, then calculated the

consecutive totals, then the individual means and finally the departures

of these means from the normal values. This last operation was some-

what arbitrary and I would certainly have done better by taking the de-

partures from the ten-yearly means.

88 ANNALS NEW YORK ACADEMY OF SCIENCES

At the beginning, I had no intention of doing the work for all the years

and so I made the annual departures correspond to those given in the

“Monthly Weather Review.” These departures are probably taken from

the means of the entire series of observations, and these means increasing

or decreasing as the number of years taken into consideration increases,

the departures are necessarily not homogeneous. This lack of homo-

geneity has no importance, since I adjusted the values, for each year, so

they would correspond to the last annual departures (from the normals)

given in the annual summaries of the “Monthly Weather Review.”

The material which I have at hand consists of ten annual maps, giving

the distribution of the annual departures from normal means, and of one

hundred eight consecutive maps, showing the progressive changes of the

map of each year into that of the following year.

First of all, I must say that comparing the ten annual maps, obtained

by utilizing district departures, with the ten detailed maps, described

previously, one has to admit that the method of grouping the results of

different stations to obtain regional averages is most inconsistent and

defective. One can imagine how inefficient our daily weather maps would

be if instead of utilizing the values given for individual stations we made

regional averages. Still, even such smoothed weather maps would give

some idea about the position of lows, and highs and cold waves could also

be located, though in a very vague and unsatisfactory way.

On the consecutive maps I have drawn, the pleions and antipleions are

of course badly deformed and most interesting details are lacking, but

the more or less progressive displacements taking place can easily be

followed and the precise moments when the important changes in the

distribution of temperature occur are detected without great difficulty.

I will therefore compare the maps, simply in order to reach a better

understanding of the transformations of the annual departure maps from

one to another.

1900-1901. The consecutive maps show that the antipleion of 1901

came from the south and progressed westward over the States. After

some minor oscillations of the quasinormal line,?* the upward movement

of the antipleion starts with the map of September, 1900,—August, 1901.

The annexed diagram shows the successive positions of this line on the

consecutive maps for the periods ending in August, September, October,

November and December, 1901 (Fig. 32). The western pleion remained

practically unchanged.

26 These quasinormal lines deal with departures from normal values, and, evidently,

differ from those of the maps expressing the distribution of departures from ten yearly

means.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE — 89

1901-1902. The western antipleion of 1902 is not the southeastern

antipleion of 1901. The consecutive maps show that the center of the

antipleion remained nearly stationary over the Atlantic, east of Georgia

or South Carolina, and that, at the end of the year, the negative area ex-

tending over the States moved eastward.

The following diagram (Fig. 53) shows the successive positions of the

quasinormal line for the consecutive maps of November, 1901,—October,

1902, until January—December, 1902. The maps show an interesting

feature concerning this antipleion. Its disappearance from the map was

preceded by a progressive shrinkage followed by an expansion. The

shrinkage began with April, 1901,-March, 1902, and continued until

June, 1901,—May, 1902, when the quasinormal line lay from Washington

over Louisville and Memphis towards Vicksburg; then, the negative area

“py

Fic. 32.—Successive positions of the Fic. 383.—Progressive displacements of

quasinormal line the antipleion of 1901

increased again progressively until November, 1901,—October, 1902, and

was followed by the eastward movement shown on the diagram.

The consecutive maps do not give a satisfactory account of the forma-

tion of the negative wave which, on the map of 1902, extends between the

pleions of Canada and Mexico. The regional departure maps do not

show the existence of the two pleionian centers of 1901 (Fig. 23) until

towards the end of the year. The movement of separation begins with

December, 1901,-November, 1902, and corresponds to the rapid drift of

the eastern antipleion towards the southeast. The western antipleion

of 1902 (Fig. 24) came from the southwest and spread out, progressively,

over the entire area of the United States.

1902-1903. Evidently the quasinormal line of the consecutive maps

is not the same as the quasinormal line of the departure maps from the

means of the decade 1900-1909, but the displacements shown and the

transformation of the consecutive maps must be similar to those of the

detailed yearly maps. I repeat this statement to avoid misunderstanding.

90 ANNALS NEW YORK ACADEMY OF SCIENCES

On the consecutive map of 1902, the western antipleion is very much

less developed than on the departure map of 1902 (Fig. 24)- This is

evidently due to the fact that the normals adopted in the “Monthly

Weather Review” are very different from the means of 1900-1909.

The following diagram (Fig. 34) gives the successive positions of the

quasinormal line on the maps ending with October, 1902, December, 1902,

February, 1903, May, 1903, and August, 1903. Figures 35-37 are the

consecutive maps for the years ending with September, October and No-

Fig. 34.—Displacements of the quasi- Fic. 36.— Departures of temperature

normal line averages for November, 1902,-October,

1808

Ni Bri Sa : AG ‘a

Fipenany =

TORS S Gennes:

~ ae os Bb

Fic. 85.— Departures of temperature Fic. 37.— Departures of temperature

averages for October, 1902,-September, averages for December, 1902,-Novem-

1903 ber, 1908

vember, 1903. These diagrams show plainly that we do not have to

deal with a simple displacement from west to east or southwest to north-

east.

We see that the pleion and antipleion are not only dependent upon

each other for their displacements but also have a tendency to remain on

the continent. The antipleion moving eastward displaces the pleion,

first northward then northwestward and finally westward. The pleion

and antipleion move en bloc contra-clockwise.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 9]

1903-1904. The map of 1904, without a doubt, expresses the con-

tinuation of this dynamic phenomenon. The change, however, in the

respective positions of the two centers is not progressive. The following

four maps (Figs. 38-41) show indeed that for February, 1903,—January,

1904, the temperature conditions were still very similar to those of 1903,

whereas for April, 1903,—March, 1904, the distribution of the negative

departures already had the character of the map of 1904. The develop-

ment of the western pleion was delayed, and it is only on the consecu-

tive map ending in November that its maximum development is reached.

WM VA

Fic. 38.— Departures of temperature Fie. 40.— Departures of temperature

averages for February, 1903,January, averages for April, 1903,-March, 1904

1904

St a ee ed woh

‘ aN

Min

al |

. “J

ees

Fic. 39.— Departures of temperature Fic. 41.— Departures of temperature

averages for March, 1903,February, averages for May, 1£03,-April, 1904

1904

1904-1905. The consecutive maps showing the transformation of the

temperature conditions of 1904 into those of 1905 are most interesting,

because they show a slow and continuous movement. The pleion and

antipleion remain bound together and both remain on the continent;

but the displacement is reversed and now it goes clockwise. The follow-

ing two diagrams (Figs- 42-43) will be sufficient to demonstrate inter-

mediate stages between 1904 and 1905. The first one is of the twelve-

92 ANNALS NEW YORK ACADEMY OF SCIENCES

monthly means ending with February, 1905, and the second gives the

distribution of the departures of July, 1904,—June, 1905.

1905-1906. The map of 1905 (Figs. 27 and 44) shows a large pleion

in Canada, another on the West Indies and Florida, and an extensive

antipleion with two centers, one in ‘Texas and the other on Nova Scotia.

The consecutive-map of February, 1905,-January, 1906 (Fig. 45), shows

the two pleions joined together, separating the two antipleionian centers.

The following maps show the shifting and final disappearance of the

northeastern antipleion, but the southern or southwestern antipleion re-

mains, undergoing small changes of position or extent.

Fic. 42.— Departures of temperature Fic. 44.— Departures of temperature

averages for March, 1904,-February, averages for January—December, 1£05

1805

Fig. 48.— Departures of temperature Fig. 45. — Departures of temperature

averages for July, 1904,-June, 1£05 averages for February, 1905,-January,

1806

The variation of the departures is of some interest. The highest de-

parture in the north is + 1°.1, for 1905, in the North Dakota district

+ 2°.1, for February, 1905,January, 1906, + 2°.3 for March, 1905,—

February, 1906, and then decreases to + 1°.0 and afterwards increases’

again progressively until November, 1905,—October, 1906, when it reaches

+ 2°.5. At the center of the antipleion, the negative departures for the

first three consecutive maps are — 1°.4, —1°.1 and —0°.8. A general

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 93

increase of temperature takes place all over the States, in the pleionian

as well as in the antipleionian area. Then, towards the end of the year,

the negativity of the antipleion increases with the increase in positivity

of the pleion.

_ The contrast between the positive and negative departures decreased

and then increased. This particular case shows therefore very well the

importance of minor oscillations, taking place independently of the dis-

placement of pleions and which, at the same time, may interest larger

areas than those covered by pleions and antipleions. I reproduce only

Fic. 46.— Departures of temperature Fic. 48.— Departures of temperature

averages for January—December, 1906 averages for April, 1906,-March, 1907

+c AN

Fic. 47.— Departures of temperature Fic. 49.—- Departures of temperature

averages for February, 1906,January, averages for June, 1906,-May, 1907

1907

the first two consecutive maps showing the junction of the two pleions

(Figs. 44, 45). The other maps simply illustrate a progressive disap-

pearance of the southeastern center and the minor oscillations of the

southern antipleion.

1906-1907. The maps of 1906 and 1907 (Figs. 28, 29), by their pre-

cisely opposite character, seem to indicate a simple seesaw oscillation in

the distribution of temperature.

The consecutive maps contradict this supposition. The following dia-

94. ANNALS NEW YORK ACADEMY OF SCIENCES

grams, representing the conditions for 1906, February, 1906,—January,

1907, April, 1906,-March, 1907, and June, 1906,—May, 1907 (Figs. 46-

49), show that the transformation began with a shght rotary movement,

followed by a displacement of the pleionian center from the north to-

wards the south, and then by a displacement of the pleion towards the

west and of the antipleion towards the east.

1907-1908. The pleion of 1908 (Fig. 30) is so similar to that of

1907 that one would think that nothing extraordinary happened during

the year and that there was simply a shifting of the pleion towards the

northeast. In reality, the consecutive maps show that the pleion and

antipleion moved first around, with the hands of a clock, so that for

February, 1907,—January, 1908, the quasinormal line had already ex-

tended from North Dakota towards Tennessee and Virginia, as is shown

on the following diagram (Fig. 50), then the antipleion extended farther

south (April, 1907,—March, 1908), and from then on it was driven away

progressively in a northeasterly

direction. The lines of the dia-

gram show the successive posi-

tions of the quasinormal line.

The 1908 western antipleion is,

in June, 1907,-May, 1908, al-

ready on the plateaux and from

then on its negativity increases

progressively.

es C j r ac

Fig. 50.—Displacements of the quasi- 1908-1909. Finally, the last

normal line on the consecutive de- twelve consecutive maps show

parture maps of February, 1907,—Jan-

¢ ane ] = PC

wary, 1908, till July, 1907,—June, 1908 that the axis of the pleion of 1908

first turned slightly to a north-

south direction, then moved eastward, then back again to the west. For

November, 1908,—October, 1909, there were two pleionian centers, one

in North Dakota, the other in Texas. The advance of the antipleion

towards the northeast is seen only on the last consecutive map.

So far, the consecutive maps have served only to explain the transfor-

mation of the departure map of one year into that of the following year.

One might be satisfied with the results obtained, the consecutive maps

having served their purpose in a satisfactory way.

The principal conclusion gained is that the method used could be

applied to seasonal forecasting ; but it is evident that, for such a purpose,

it would be necessary to draw the consecutive maps as correctly as possi-

ble, by calculating the means for all the individual stations.

It is also evident that the same would have to be done for the rainfall

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE = 95

data, the atmospheric pressure and the velocities and directions of the

observed winds.

In the present state of our knowledge of the phenomena governing the

climatical variations, however, it would be most unscientific to try to

make seasonal forecastings, since, at present, we see only the possibility

of arriving at practical results by pursuing patiently the research work

in a well-established direction. With the immense amount of work which

yet remains to be done before a clear understanding of the climatical

variations will be reached, any test of the method employed, in order to

show its practical value, would be completely out of place.

To show how each step forward leads to new questions to be solved

and new research work, having apparently nothing in common with the

pursued purpose, I will note a few problems arising from a closer ex-

amination of the consecutive maps.

First of all, during the years 1900-1909, the pleions as well as the

antipleions displayed a tendency of persistence. No seesaw movement,

between a pleion and an antipleion, leading to the gradual disappearance

of both and then to the formation in situ of a pleion on the place for-

merly occupied by the antipleion and vice versa, could be traced. Minor

seesaw oscillations took place, but they served simply to increase or de-

crease the contrast between the pleions and antipleions without destroying

them. Together with a tendency to persist goes a tendency of displace-

ment. These displacements are generally gradual and continuous, but

sometimes they may be very rapid and in striking contrast to the nearly

stationary conditions which preceded or followed the rapid change of

position. The problem is, then, to know what makes a pleion remain on

the map during several years and what makes the pleion move from one

region to another.

Another fact is the tendency of the pleions and antipleions to remain

on the continent. In other words, the phenomenon of the variation in

the distribution of the anomalies of yearly temperatures in North Amer-

ica is to a great extent a purely North American phenomenon.

This leads naturally to another question of some importance. The

pleions and antipleions seem to be correlated or bound together. One

depends on the other, and if one moves the other moves. The area of the

North American continent seems not to be wide enough for the simul-

taneous presence of many pleions and antipleions. In order to remain

on the continent, the motion of a pleion involves a displacement of the

antipleion in an opposite direction. A rotary movement is the conse-

quence. It is a pendulation.

The following diagram shows in a schematic way the pendulations of

96 ANNALS NEW YORK ACADEMY OF SCIENCES

the pleionian center (Fig. 51) and expresses simply the tendency of the

displacements, during the years 1900-1909, and may serve as an illustra-

tion facilitating the comprehension of the problem. For precision it

would have been necessary to have detailed consecutive maps.

sae The principal problem is of

ae PEE eer ALYY course, what keeps the pendula-

eae ware

ee ar

Th \ at; ie

tion coing ? Without some exte-

rior impulse, the movement would

die out or could not even origi-

nate. It seems to me highly im-

probable that a mechanical work-

ing as is exhibited on the diagram

could be due to variations of the

Atlantic ice conditions. Without

doubt, it is the cause of the for-

mation of pleions which, repeating itself more or less periodically, gives

the impulse to the clockwork.

The Russian pleions have shown some correlations with the equatorial

variation of temperature, illustrated by the consecutive curve of Arequipa.

The consecutive curve of New York also belongs to the Arequipa type.

We see now how the tendency of the pleions to maintain their existence

complicates the problem of their mode of formation or origin.

The following diagram (Fig. 52), which expresses graphically the last

oof heb

a 7

fot AY

TA Wwe

Fic. 51.—Pleionian pendulations

Fic. 52.—Pleionian amplitudes and the Arequipa curve

problem I have to mention 1m connection with the study of consecutive

maps, shows plainly that, independently of the pendulations, the Are-

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 97

quipa variation affects the entire system of North American pleions and

antipleions.

I have taken the differences between the highest and lowest departures

for each map, in other words, the total amplitude between pleions and

antipleions. The curve is reversed and I have drawn the Arequipa curve

underneath to make the comparison easier. From 1900 until 1906 these

two curves are similar. Between 1906 and 1907 an interesting anomaly

is noticed. The Arequipa temperatures decreased from 1900 to 1909.

In the United States, the differences between pleions and antipleions were

also decreasing during that period of years.

CONSECUTIVE TEMPERATURE CURVES FOR SEVERAL STATIONS IN THE

UNITED STATES

In order to simplify the work, it was necessary to take into considera-

tion the consecutive means of district data, and it is evident that the

overlapping maps obtained from these figures are but a first approxima-

tion. I will now complicate the problem anew by showing how.the pass-

ing pleions and antipleions affected the succession of means observed at

individual stations.

TABLE V.—Ha«rtreme values of consecutive means

Highest Lowest Sith on

IMEVA RWIS Uy avetcrens rsie ccsicle Boe ersten Meiayeanbatey 77.6 74.3 Baa IL fs3

EDV ATYU TO rey carats beter steyie ter catactte aire fain cast oc arcbay cue a 73.0 69.6 2.4 19

ENON T) Sache cd BIO Cae ie OO OID Oe eres 68.1 64.7 a4! 1.9

RUA GIS rotor ote ete areas aeabara te aocue cohen evarenatems Gens 58.0 3.8 Drei

Wann OM rae prenatal neko, ue ore roere eel nan eietans 56.6 Boia! 4.5 2.5

ING Wg VOD a poretete Oi med Seer Mcn veins AT ari awh 19) 4) 50.2 aye & 3.2

BOTTA sarees recto the uskorene eo) hoe cus oleae 46.7 AD ei: 4.6 2.6

ASH OT te seacket herrea eae cote seenaliete adaeshes 43.6 38.9 4.7 26

Sa mliteStehMamie see sno. c\ 5 Sec ctyace oie aw ogee pea | aX5}603 5.8 ieee

1S) UUM Gece eet rays cestcs cere te done DNs Ich ieee cA 41.5 349)5 (0) 6.5 3.6

Uy OME teptere ret meant coro chic ues oes te ado 44.9 37.6 33 4.1

WYUNNEES): COMTEASES ots caer fs eee es a ee a ae eee cee eens 48.6 43.5 En al 2.8

INOEUDBB Tater cats aie seater erAveccune: wakene 51.8 47.9 3.9 ey

\ubaio) ou Lesa Pe eerie tay are Ace ORME ope ry eee Bee ee 57.9 54.4 33,5) 19

SHECVEVOL Ee warmth ere cons ore neiebeecho nn 67.6 63.8 Bye) Pe Al

Newi Orleans tics care acts Elects are lnicus Tle@ 67.7 3.9 Qe

LBROIREN IEE ahs chetevenr cuca tr yet EIR OL RRL ee eet a RBS 7 50.4 see bets:

MEOSWAN SOLER rete uras ic) setacshncce ciuvhotevetaustels lans.‘e 64.6 61.0 3.6 2.0

USS Obra ey acetone at resto eraiere Chie ie 65.1 6272 2.9 iG

Corpusy CHristimasctactie cee ee cele eke 72.4 69.0 34 1.9

TACO RU Oe eee perch e, OtaIn ete ee CEE eRe aie Se ae ee 58.8 56.3 PASH) 1.4

Not taking into account, at present, the actual monthly means, I will

examine the consecutive annual means, or rather the curves expressing

graphically the variations of these figures. :

The stations for which T made the necessary calculations are Eastport,

Portland, Me., New York, Washington, Raleigh, Savannah, Tampa, Key

98 ANNALS NEW YORK ACADEMY OF SCIENCES

West, Sault St. Marie, Duluth, Havre, Miles City, North Platte, Wichita,

\ TO +} Tow *l ac . ni “alee . x \

Shreveport, New Orleans, Eureka, Los Angeles, El Paso and Corpus

Christi. In figures 53-56, I reproduce the diagrams obtained and in

“Yormpa

Sovannoly

Raleigh

Washing on

| New York.

(09 19/19.

Fic. 53.—Oonsecutive temperature curves of Atlantic coast stations

Table V, I give the values of the highest and lowest consecutive means

and their differences in °F. and °C.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 99

The curves of the stations along the Atlantic coast have already been

published in my paper on the climatical changes recorded in New York

City. In that paper I said:

“The Arequipa curve descends; all the others, on the contrary, are ascending

curves (Fig. 53). This contrast leads to the conclusion that the pleionian

crests are independent of the long-range variations. Annual departures from

ten-yearly means may therefore lead to very erroneous conclusions. At Are-

quipa, for example, the annual means for 1901 and 1902 are higher than the

average of the decade taken into consideration; they form positive departures,

elthough belonging to a depression of the curve.

“This is a strong argument against using such departures without consider-

ing at the same time the trend of the curves. Now, the Arequipa curve has

four crests and four depressions. So has the curve of New York. The most

important difference between the two curves is that the maxima and minima

of the curve of New York occur a few months later than those of Arequipa.

One may say about three months later.

“All the other curves are identical with the curve of New York in some

particulars. For example, the depression of 1904 appears on all the curves.

It occurs sooner in Tampa and Savannah than in Raleigh, Washington and

New York. In Portland, and even more so in Eastport, this depression is

very much retarded. The first crest in the Eastport curve, furthermore, re-

appears, although greatly diminished, in the first depression of New York,

which later corresponds to that of Arequipa. One can follow the gradual

attenuation of this feature going south. For 1902 we have a positive de-

parture in Eastport belonging to a pleion. This pleion (1901-1902) has evi-

dently nothing in common with the equatorial variation of Arequipa and the

other tropical stations. It is another wave having another origin and whose

occurrence is marked all along the Atlantic coast in the midst of the anti-

pleionian deficiency of temperature. About 1905 the curves of the southern

stations differ greatly from the Arequipa curve. The curves of the northern

stations, on the contrary, are similar to the curves of Arequipa and New York,

except at the end. In Eastport we indeed notice a crest between 1909 and

1910 which is not a retarded crest, and going south, we observe the same

attenuation of this phenomenon as between 1901 and 1902.”

I will compare the other curves in a similar way.

In the following diagram (Fig. 54), I reproduce the curves of Miles

City, Duluth, Sault St. Marie and Eastport. These curves are very much

alike. The only striking difference is that the variation of Miles City is

more or less in advance of the others.

The curves of Fig. 55 are those of the line of stations between Havre,

Mont,, and New Orleans. The variation of New Orleans is to a certain

extent opposite to that of Havre, and so it is most interesting to compare

the diagrams one by one and see how the features of one curve gradually

disappear in favor of those of other curves. The curve of Wichita, in

particular, has a most unsettled appearance, since it participates in the

100 ANNALS NEW YORK ACADEMY OF SCIENCES

variations of the northern plateaux as well as of those of the Gulf. A

certain similarity with the curve of Aachen (Fig. 11) is undeniable.

Some other localities of the middle states would give perhaps even a

better example of an unsettled variation.

Figure 56, on which the consecutive curves of Hureka, Los Angeles,

El Paso and Corpus Christi are reproduced, shows that on the Pacific, as

Miles Gly.

Duluth.

Sault S¥.

Marie.

Eastport.

Fic. 54.—Temperature variation of Montana (Miles City) compared with that of

Maine (Fastport)

well as on the Atlantic, the pleionian variations are very pronounced,

presenting a striking difference with northwestern Europe. Moreover,

the curve of Eureka is similar to the Arequipa curve, and even shows

exceedingly interesting small details of the Arequipa curve, details which

cannot be ascribed to chance circumstances. It is also worthy of note that

the Eureka variation is in advance of that of Arequipa. The pleionian

crest of 1904-1905 is evidently out of the question. This pleion appears

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 101

even sooner in Los Angeles, where it corresponds in time to the principal

antipleion of the curves of New York and Arequipa; but brachypleionian

particularities, such as the V-shaped depression of March, 1909,—Febru-

Miles City,

Wi chika.

Fic. 55.—Temperature variations in Montana, Nebraska, Kansas and Louisiana

ary, 1910, appear later in Arequipa than in Eureka. The El Paso curve

shows a variation opposite to that of Arequipa and retarded. The Corpus

Christi curve is more complicated, opposition and similarity of variation

being combined.”

102 ANNALS NEW YORK ACADEMY OF SCIENCES

We may say, therefore, that the consecutive curves of temperature for

the United States, if compared with the Arequipa curve, may belong to a

direct type similar to the Arequipa variation (considered as a standard

of the equatorial or direct variation), or to an inverse type.** Some

curves, it may be added, must be called indifferent, since, to a certain

extent, they belong to both types of variation at the same time. Finally,

there is the independent type. 1

Arequipa ;

Eureka.

Los Angeles.

E\ Paso.

Fic. 56.—Comparison of variations in California and Texas with the Arequipa curve

Most curves may belong, temporarily, to one type or the other, but this

is not a complication, because, if the results gained from the comparison

of the consecutive maps are kept in mind, it is plain that it could not be

27 Compare the maps published by FrANK H. BiGELow: “Studies on the circulation of

the atmospheres. . . .’’ Monthly Weather Review, Vol. 31, p. 515. Washington,

1903. Also: Sir NorMAN Lockypr and Wm. J. S. Lockyrr: “The behaviour of the

short-period atmospheric pressure variation over the earth’s surface.’ (Proc. Roy. Soc.

London, Vol. 73, p. 457. London, 1904.)

AROTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 103

otherwise. Since the pleions displace themselves, the crests of the curves

cannot occur simultaneously everywhere, and since it has not been possi-

ble to detect important and persistent seesaw centers, it seems a prtort

very improbable that the direct and inverse types of variation could be

characteristic for certain given locations. Therefore, there is no fixed

location for the inverse or compensating type.

An inspection of the consecutive curves shows, however, that in New

Mexico, Arizona and Southern California the existence of a center, where

the variation displays a striking preference to belong to the inverse type,

may be suspected, and that, on the contrary, in Pennsylvania and Oregon,

the direct type must be predominant.

Are these locations centers of origin of pleionian variations? Not

necessarily. Besides, the records of only ten years of observations are

insufficient to give definite results. Even such as it is, the result gained

leads to further investigations in regard to the question of the mode of

formation of pleions in situ.

Leaving this question as an unsolved problem, I will pass to another

most puzzling subject. .

Since, for certain parts of the United States, the consecutive tempera-

ture curves belong to the direct type,—that is to say, are similar and

coincide more or less in time with the equatorial curves,—the impulse

producing these variations must be the same as that which produces the

tropical variations. This impulse is evidently extra-terrestrial. There-

fore, where the variation is direct, the departures of temperature will not

be due to abnormal conditions of atmospheric circulation but will, on the

contrary, produce such changes of atmospheric pressure, wind direction

and velocity, etc., as may be characteristic for pleions or antipleions. On

the maps the pleions do not disappear: they move away.

Now the question is how—in a direct type of variation—the pleion

corresponding to the second crest of the consecutive curve is renewed.

Is it the same pleion coming back from the region it was pushed away

from by the formation in situ of the direct antipleion, or is it a new

pleion, and if so what became of the first one?

Let us call the pleionian crests of the Arequipa curve A, B, C and D

(Fig. 1). The consecutive maps show that the crest B of New York

went northwest over Canada and then southwest towards California. The

pleion came back nearly the same way during 1904-1906. The crest C

of New York is therefore the same as B; but, if we try to follow this

pendulation on the consecutive curves of individual stations, we do not

succeed very well. This is because, as has been shown in Fig. 52, the

amplitude of the departures changes independently of the pendulation.

104 ANNALS NEW YORK ACADEMY OF SCIENCES

The pleions pendulate and surge at the same time. An old pleion may

be reintensified. In the case of the pleions B and C the surging is noth-

ing but the superposition of a new pleion upon an old one, so that C is

the residual of B, plus a new impulse produced in situ under the influence

of the direct solar action. In this way, it is conceivable why the pleionian

variations may be more important on the North American continent than

the identical variations in tropical regions. «

ABpout TEMPERATURE VARIATIONS AND THE CHANGES OF THE ARCTIC

Icke CONDITIONS

In order to connect the European annual departure maps with those

of the North American continent, I utilized the results of the observa-

tions made at St. Johns, N. F., Upernivik, Jacobshavn and Ivigtut, on

the west coast, and Angmagsalik, on the east coast of Greenland, those

of the Icelandic stations Stykkisholm, Vestmanné, Grimsey and Berufjord

and, finally, the observations made in Thorshavn of the Faroé Islands.

For information about the variations which occurred on the Atlantic

Ocean, I took the results of the observations made in San Juan (Porto

Rico), Hamilton (Bermuda), Angra do Heroismo and Ponta Delgada

(Azores), Funchal (Madeira), St. Vincente de Cabo Verde and, finally,

those of St. Helena.

The St. Helena observations were extracted from a report of J. S.

Dines.** The portuguese data were kindly sent to me by the Director of

the Observatory of Lisboa, in manuscript for the years 1906-1909 and in

printed form for the previous years.*® The data for Bermuda were copied

from the “Monthly Weather Review” and the reports of the Meteoro-

logical Service of Canada. Those for Porto Rico were sent to me by

Section Director Oliver L. Fassig. The results of the observations made

at Danish stations were sent to me by the Director of the Meteorological

Institute of Copenhagen.*® Finally, the data for Newfoundland were

copied from the Canadian Reports. Unfortunately, for the period of

years taken into consideration, only the records of St. Johns are complete.

It would have been very desirable to have some records for Labrador

and the Hudson Bay region, to obtain a closer connection between Green-

land and Canada, but the distances between Ivigtut and St. Johns, Father

Point and Quebec are so much smaller than the ordinary pleionian dimen-

°8 JOHN SOMERS DINES: Climatological tables for St. Helena, with a report on

(Meteor. Office Publ. No. 203: The trade winds of the Atlantic Ocean, London, 1910.)

* Anaes do Observatorio do Infanta d. Luis. Obsarvacoes dos postos meteorologicos.

%° Meteorologisk Aarbog . . . Anden del: Faeréerne, Island, Grénland og St. Croix.

Udgivet af det danske meteorologiske Institut,

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 105

sions, that it is perfectly safe to say that the records of Greenland and

Iceland are entirely sufficient for the purpose of the questions I had to

solve.

In Table VI, I give the annual departures from the ten-yearly means

of temperature for the stations now taken into consideration, the dia-

Upernwik.

Jace \shavn.

vighwr.

Anqmagiaki.

Stykkighelm.

Grimsey.

Berufierd.

Vestmanwa

pa wiee

Thorshavn-

Fic. 57.—Temperature variations in Greenland, Iceland and Faroe

grams (Figs. 57-60) express graphically the succession of consecutive

means, and in Table VII, I give the highest and lowest of these values

as well as their differences.

. ANNALS NEW YORK ACADEMY OF SCIENCES

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ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 10%

The following questions may be taken into consideration :

1). Is there any trace of the Arequipa variation on the consecutive

curves of Arctic stations ? :

2). How far do the pleionian variations of the North American conti-

nent extend over oceanic areas ?

3). Is there a system of Atlantic variations independent of those of

Europe and North America ?

4). What are the connections between the continental variations and

those observed in the Arctic regions ?

5). Do the Arctic ice conditions influence the variations of annual

temperatures observed on continental areas ?

Sy. Valves $

Fic. 58.—Temperature variations in Newfoundland and Maine

The curves on Fig. 57 give an answer to the first of these questions.

Two types are distinguishable: the west Greenland type, best represented

by the curve of Jacobshavn, and the Icelandic, or let us say Grimsey type.

Angmagsalik, on the east coast of Greenland, belongs to the Icelandic

type and the curve of Ivigtut is transitional, since it is similar to the

curve of Jacobshavn until 1905 and very much more like the curve of

Angmagsalik after 1905 or 1906.

If we compare the curves of Jacobshayn and Grimsey with the Are-

quipa curve we must admit some similarities which are too well pro-

nounced to be ascribed to a simple chance circumstance. With the ex-

ception of the part comprising the consecutive means of February, 1903,—

108 ANNALS NEW YORK ACADEMY OF SCIENCES

January, 1904, to October, 1904,-September, 1905, the Grimsey curve

shows all the crests and depressions of the Arequipa curve slightly re-

tarded. Jacobshavn, on the contrary, is in advance of Arequipa.

Grimsey is a small island situated on the Polar Circle, north of Ice-

land, and the latitude of Jacobshavn is 69° 13’ N. Both of these stations,

therefore, are under the influence of polar currents and polar ice.

If the consecutive temperature curves of these stations display simi-

larities with the Arequipa curve, and, in consequence also with thoge of

Bulawayo and Mauritius, we must admit that it is absolutely out of the

question to search for an explanation of these variations in the changes

of polar ice conditions.

The second question could not be answered by a simple inspection of

Funchel.

Fic. 59.—Temperature variations in the Azores, Madeira and Cape Verde Isl.

the departures given in Table VI and the curves of consecutive means

of Figs. 59 and 60. Therefore, I have drawn maps showing the probable

connections between the European and American pleions. The map for

1909, which I reproduce here (Fig. 61), may serve as an example.

On this map there is a continuous chain of pleionian centers extending

from northeastern Russia over Greenland and Labrador towards Texas

and probably Mexico. The quasinormal line goes between Iceland and

the Faroes, the departures being + 0°.2 in Berufjord and Vestmanno

and —0°.4C. in Thorshavn. In the latitude of Newfoundland, the

quasinormal line must go between the continents and run in a southern

direction towards the Azores, where Angra do Heroismo belongs to the

American pleions and Ponta Delgada to the western European antipleion.

The other maps also show, in a convincing way, that there can be no

question of a special Atlantic variation. Parts of the Atlantic area be-

long to one pleion or the other or are covered by an antipleion separating

pleions.

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 109

The fourth question, “What are the connections between the conti-

nental variations and those observed in the Arctic regions?” can best be

answered—with the maps on hand—by saying that the north polar annual

temperature changes form, probably, an intrinsic part of those occurring

in Europe, Siberia and North America. The ice-covered Arctic Ocean

connects Nowaya Zembla and the Siberian shores with Arctic America

into one immense continental area. On this area, pleions and antipleions

are formed and conjugate into one system.

The question, “Do the Arctic ice conditions influence the annual tem-

peratures observed in Europe and North America?” ought therefore be

reversed into the question, “How do the pleionian—or let us say the

Fic. 60.—Temperature curves at St. Helena, Arequipa, Porto Rico and Bermuda

Arequipa variations—influence the ice conditions?” ‘This is a very wide

subject, about which much might be said.

Air temperature is only one of the factors influencing the drift of polar

ice. Ocean currents, and especially the winds, are more important factors

than temperature. It is very well known that in the Arctic, as well as in

the Antarctic, the ice conditions of certain regions may vary considerably

one year from another and, from the knowledge gained in the North

American archipelago—the Northwest Passage in particular—we must

infer the existence of long-range or even secular variations.

The quantity of icebergs drifting down into the path of the transat-

lantic ocean steamers also varies considerably. The same may be said

about the Antarctic.

110 ANNALS NEW YORK ACADEMY OF SCIENCES

Speaking of ice conditions we must make a distinction between ice-

bergs and sea ice, the conditions under which these two kinds of ice are

produced and drift being absolutely different.

Icebergs are anchored deep in the water and are much less influenced

by the direction of the winds than by the ocean currents. They originate

at the glaciers. The quantity of icebergs carried down through Davis

Strait, for example, and along the Newfoundland Banks, will depend

mostly on the factors which acted upon the flow of the glaciers. Sup-

posing normal conditions of the glaciers (for example, a regular advance),

a succession of cold years followed by a warm year and, in particular, an

abnormally warm summer, will favor considerably the production of

icebergs.

In 1909, for example, much ice was noticed in the Atlantic.**

The consecutive temperature curves of Upernivik and Jacobshayn give

an explanation to this fact. During 1906 and 1907 we notice a remark-

able depression in the curves (Fig. 57), followed by a steep ascent, culmi-

nating, in 1908 and 1909, farther south, in Ivigtut.

The drift of polar sea ice, on the other hand, is a most complicated

phenomenon. In the Antarctic, the conditions are very much simpler

than in the Arctic, and, even there, the drift is far from being a simple

function of the velocity and direction of the wind.

For the north polar basin, the distribution of the surrounding lands

and islands, and the existence of well-pronounced ocean currents, compli-

cate the ice-drift to such an extent that the possibilities of a successful

study of the correlations between the anomalies of the meteorological con-

ditions and the abnormal changes of the ice conditions is evidently most

problematical.

The observations collected by the Danish Meteorological Institute and

printed every year concern the ice conditions during the navigable season

only and are naturally restricted to the peripheral areas of the frozen sea.

In some waters, we have to deal with winter ice, which must melt away

during the summer; in other waters it is old drifting polar ice which

hinders navigation. To correlate these variable ice conditions, of the

navigable season of some arctic seas, with atmospheric temperature data

of distant stations is a task which can lead only to very uncertain results.

“In the special reprint of the Nautical-meteorological Annual of the Danish Meteoro-

logical Institute, “‘Isforholdene i de arktiske Have, 1909,” it is said:

“Off New Foundland and on the transatlantic steamer routes uncommonly much ice

was observed, floes as well as icebergs. As early as February there was much ice, an@

from March to July the conditions were more unfavorable, than they have been for

many years. The icebergs held out uncommonly late, the navigation being much ham-

pered at Cape Race as late as August. It was not till September that the ice com-

menced to decrease, but still many icebergs were to be met in Belle-Isle Strait and far

off-shore off the Strait.”

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 111

Nevertheless, comparing the yearly temperature departures of the Ice-

landic stations and Angmagsalik, on the east coast of Greenland, with the

state of the ice in Denmark Strait and north of Iceland, one finds that a

correlation is undeniable.

Now, why is the variation of Grimsey (Fig. 57) so much more accen-

tuated than that of Berufjord or Vestmanné? It seems evident that the

proximity of the ice must be the cause.

~ Consequently, the Icelandic consecutive temperature curves could be

taken as an example proving the influence of the ice on the variation of

temperature. The ice conditions of Denmark Strait must greatly influ-

ence the temperatures of Grimsey, especially some of the monthly means,

by accentuating them one way or the other. It is not, however, the ice

which causes the observed variations of temperature producing the for-

mation of pleions and antipleions. The departure maps I have drawn

show this plainly.

The changes of ice conditions are more or less local phenomena re-

stricted to small areas; the formation and development of the pleions and

antipleions, on the contrary, are a universal phenomenon.

CONCLUSIONS

In the case of the annual departures of temperature for the years 1891

to 1900, which I utilized in my previous investigations, I dealt with the

results of observations made all over the world and gained therefore some

precise knowledge of the distribution and extent of the pleions and anti-

pleions, and found that the years 1893 and 1900 were particularly inter-

esting, the first being a year of predominant antipleions and the second

being a typical pleionian year.*?

In 1900, the pleions were not only very accentuated, with exceptionally

high departures at their centers, but the areas they covered were fused

together in such a way that the antipleions appeared as isolated patches

on a pleionian background. The year 1900 was exceptionally warm, the

temperature of our atmosphere being above the average, the negative

areas being insufficient to compensate the excess of temperature of the

positive areas.

In some cases,—the map for 1909 (Fig. 61) shows it plainly,—conju-

gated pleions form bands of very extensive dimensions. In other cases,

there are intercrossing pleionian bands forming a real network with

antipleionian patches between.

= Op. cit., p. 123.

112 ANNALS NEW YORK ACADEMY OF SCIENCES

Therefore, since, as has been demonstrated in this memoir, the Are-

quipa variation is not exclusively an equatorial phenomenon, but appears,

more or less modified, in North America, Europe and even in the arctic

regions, the question is whether the years of conjoined pleions do not

correspond to crests of the Arequipa curve and whether the depressions

of this curve do not correspond to years: of isolated pleions in a net of

conjoined antipleions. In fact, the maps for 1900-1909 show that the

years 1904 and 1907, closely following the Arequipa depressions, are years

of conjoint antipleions, and that the years 1900, 1908 and to a certain

extent 1905, are pleionian years with isolated antipleions.

Fic. 61.—Pleionian connections

The existence of macropleionian variations, the close correlation of the

pleionian phenomenon with the Arequipa variation, the compensating

antipleions, and, finally, the dynamic character of these climatic changes,

eliminate, it seems to me, the hypothesis attributing such changes exclu-

sively to the presence of variable quantities of voleanic dust in the higher

layers of our atmosphere.

Variations of the solar radiation must be the real and most important

cause producing the changes of our climates and keeping them in a

dynamie state.

The elaborate investigations pursued at the Smithsonian Astrophysical

Observatory, and the Mount Wilson Observations in particular, give

striking support to this conclusion.

In fact, considering the means of the solar constants, observed at Mount

Wilson during the summer months of 1905, 1906, 1908, 1909 and 1910,

and comparing the differences of these mean values with the correspond-

ARCTOWSKI, CHANGES IN DISTRIBUTION OF TEMPERATURE 113

ing differences of temperature in Arequipa, one arrives at the conclusion

that a difference of 1° F. corresponds to a change of 0.01 of the solar

constant.

It would be premature to conclude that the brachypleionian, the

pleionian and macropleionian variations are simply due to corresponding

variations of the solar constant. Other factors may indeed complicate

the phenomenon. Further research into the variations of the climates of

Asia, South Africa and Australia, in particular, must be made before

any definite conclusions can be reached. It is also evident that the sea-

sonal changes of temperature, atmospheric pressure and rainfall have to

be taken into consideration. I intend to do this.

In this paper, I have shown that in far distant regions of the globe,

simultaneously with the appearance of the Arequipa crests, pleions are

formed ; that these pleions have a tendency to persist; that, in order to

persist, one must displace another. Pleions and antipleions are corre-

lated: if one moves, the other moves. In North America the displace-

ments seem to be confined to the North American continent. In conse-

quence, the pleions must pendulate from one side to the other. More-

over, the differences between the pleionian crests and the antipleionian

depressions of temperature change. These changes of amplitude seem to

be in immediate correlation with the equatorial changes of temperature.

The Arequipa curve may, therefore, be considered as a very convenient

standard for the study of all the complicated phenomena of climatic

variations, and of those observed in North America in particular.

It appears now perfectly evident that a more detailed study of the

Arequipa variations will advance very greatly the problem of correlations

between solar and terrestrial phenomena.

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ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIV, pp. 115-170, pll. VII-XXI

Editor, Epmunp OtT1s Hovey

THE GENESIS OF CERTAIN PALEOZOIC

INTERBEDDED IRON ORE DEPOSITS

RAYMOND BarTLeTT EARLE

NEW YORK

PUBLISHED BY THE ACADEMY

4 Auaust, 1914

THE NEW YORK ACADEMY OF SCIENCES

(Lycrum oF Naturat History, 1817-1876)

OFrricers, 1914

President—Grorck FREDERICK Kunz, 601 West 110th Street

Vice-Presidents—CHARLES P. BerKeyY, RAyMOND C. OspurN,

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[Annas N.Y. Acap. Scr., Vol. XXIV, pp. 115-170, pll. VII-XXI. 4 August, 1914}

THE GENESIS OF CERTAIN PALEOZOIC INTERBEDDED

. IRON ORE DEPOSITS?

By RAYMOND BARTLETT EARLE

(Presented in abstract before the Academy, 7 April, 1913)

CONTENTS

Page

DATGRO GCE OMe earcesea ie eeree tiare ap otek e eyes SoS al ao a cla a erento oe obs Shera alte. ensues 116

ENCINO WiLEC TIM CTNES era ater anenerars ielici/sevessiee lis: a/.eie sei raelees axe teal eb ellelbpetal allows, @ a heleGuslien cues 8 HT

Bart ee As Study ang Criticism Of previous) UHEOLIES)...+ +... 5 = - 118

ASR SUE ATI META Ty neue cpac a teatcy ore are nUete eve slate sie terials 6 sales, ete araunare elese, s seks 118

Iron ore deposits of the Clinton formation................ Paertrorchs ere. 120

GOES Oa ORE sc. ote cies sess) occ yovellere suscero AiSlavs, sie eidveevee"s wlene needa pfeianeleys eve tate 120

PEXGETU Ot CP OSUES ogo leyh eter score recovereve Saye S srevels Delenel eaehelsie oa Sialaleie) ciexelevais 121

OGWELILACOZOVCs CEPOSTUES wis ners oeroinne lore ois choles cheloies opens omen fanaiteh ie, chavaiete eles 123

Wabhana deposit. INewroundland|2. secs cere sete re sere FOO OLE. 23

Morbrook and Nictaux deposits, NOva Seo0tia= ca. c-.- 260+ 65 55 124

Miraavallevadeposit.. Cape Breton: Na Shas sce cis orlee cree slelereelee 124

SUIMMArVaOt et MECOMeESSO/SCNESIS: s16< (oars cle oe. o so areca oom cities nisl seve 124

EAGT eC SP OS ULI OM ate reccy eee eps hese oa ievevacevcten stele way Stele chet cageaie eusvelene 125

SHO GRAY WET ae od poole OU ROO a OC DIC ODO Eos De EID eISnne 129

Residualgenrichment theory soso ciecee ec cle ece +c aah CaS 129

Replacenlentatheonycrrce oye ott ooo mael oes atl o nike acca eae 136

Application recent investi GatlONSs.s. cme. oc ocie oe esses eas cas sisice 131

MheoLyAOtsoriein ale sedimMentaAciOnh a-.c sek cieile c eiele elec soll cileiea ee ciate 131

SeqimentanyeaASpeCh Of OLnenWe da -musvicie crore cnele ce tecehe sis) slele ote 132

Consequences of sedimentary theory.............0c.cesee-- 132

EUG val LOT CO esas « fareterayeaiale oiratebarae traces tee ree oe ta er o iekere eee 133

Inadequacy of sedimentation in open sea......... Heractstnisteom. 13

Sedimentationkinylacoonsiysone sewer eee nee. ieee Syn ees .. 134

Theories of replacement and secondary enrichment....,.......... 135

IBEESISLEN CE TOLIOLE SCAINISE. in tervals alee ee ker ER CL cee sie eisinciee 135

lWnnrenlacedehinrestoneny recieves eietrtorie cee ete screen clon enced eo are 135

Secondarya enrichment GheOLiessee entices case canes occbee eee. 136

SumplemeplacementsteOrys ance cee. sce selec su cee HOPROCC His Or 136

Patil Artesian replacementstheory. «ccs tecncecdtns cecceweeessbecee 137

ANTIETAM “OGIVONTTLOTOSS iciche b ao! PARRA CoRR © ORE CRORE eR a EO eae 137

COMEROUIM CM PACLOLS paretrary cy ete close wre © alaxeveieier she anc ot cave arasimierd okaicse 137

CirematonzOLsarctesiaMmyyaLelscsat<)e5e acs cis os cies co alei oe cro os 138

Dy PiCMESeChlOuS Of ClinbOMmmOre sis naa clack ool oe oe se Selec, ewcene een 139

JUL TSISTONL Ie! 6 Cen Bits Ces eke Bie ec hk CRN CHE ER OLE ee hn se) So

ASTUTE OO one cic i ROOT TOR ae Ee See me a ee 139

Ses AOE Le PR ASEM a ek eel ARTS cyt) as ck © woe See. oe Hhdieichs Shc cl gedlsicis' Baveibs 148

ENGI CSS COS eters chet tatarcherne evdi-c era seveXs ie lensa ies atevale. Sicha absban s oihoue aeteke em ersi nate 144

1 Manuscript received by the Editor, 15 December, 1913. (115)

116 ANNALS NEW YORK ACADEMY OF SCIENCES

Page

WAT OUMEA 0. os fe ha ae 5 6 Zs. oro. Gyn nceieve Blue eset e ee Ruete eee tn eee Caen ie te eee 144

IWiGSE: Vir cL Bip 5 io ce Sloe ccustis ee iol aleve sete doase eher Rel el Te otel c Tete emene onen neta: Seema 145

PENNS YL VAD are oie eiousverokopstene (etateror n/sfebstcrorboyene ete talel ave retcnae Metohonetot eetete 145

IN QW OLS a aaive vas ors cycisint iatote ev entiyeweme, execs a et chante totene eo oRe le heres Nesenelte ene apemea 146

INOW aS COLLARS ic ie Sia\e beled! ereueyeicnstennlavene cleyeueie te ier s ParereneTe exe oeese ano oie 147

Artesian conditions inthe Clinton deposits ss. 1. ciieiere ce icles cierto ie 147

POLOUS TAY OLS oi cose ovee ieee aiote ale MiATCRY, cite ye ataucheceneratorsrston elena 148

TMpErviOus VAVELS/j.lelece cic\ siete le el oicla ele ote 2. ag, ao sk Oe Sk 148

Marine artesian (SLOPCS! 2s 5% ciel. ore, ofexereucle'ai chavars loelenetele ots lots Mokeliote onetonee ane 149

Infiltrationy Of meteor GswabeLs yt teteleereiclenersietetere oe eter meoteretatenenoretere 149

Ore conditions resulting from artesian slopes...............--.-ee-- 150

Depth" Of -GEPOSiESS 0 sé eeyers, em jeue.o-d eteiouc one alskoushe /oascene loaieke teeter etoteehsae tena 150

Hxtent OLGeposit GOwNeGip es cee acc cverenei, victotel ueiel anenetemeb sient cites taliotale ils!

Widexdistributionsofe Gepositstrcsy-icrsrrere ce eisietciclel ois cteaeletcacioieneretonsiets 151

Occurrence of odlitic and fossiliferous ore............----++--- 151

Variations im ichemical compositionins. sc siete cee monn erase aay b

Ve PIAGIONS) IN IEOREUTC sic.eis, acs, cue veysucieeeretere exe ehoue one Chevelete tenes ent hetereicntetons 152

Variations ANeGICHNESS ier cpesereperereieuel ocieneyeteeveietelera homers hetsues caeto or crepertete 152

Artesian replacement theory as applied to other horizons............ 152

DepositsofmwWwabana, NewLounadlan Glee se see ateroeie etel-tel eee = ene sie 153

Deposits of Mira Valley, ‘Cape Breton, Ne Scpae 2 eerste ie sie eo 153

GCeneralisummanysandeConcluslonSeerersisueiteletereieitoncie teeter ole usier ieliel eyeteietet )

PIG PLUME MS IDUMO STAD Wyevale tape rets)seaeie%el a chonener keke venckoious c: srorsey col euch ckemokeuetonsnettetenele y

INTRODUCTION

The great economic importance of interbedded iron ore deposits has

been recognized for many years. ‘l'wo types of these ores may be cited

as notable examples: first, and possibly most important, are the Clinton

hematites extending along the Appalachian system of mountains for

nearly two thousand miles and having their greatest development in the

Birmingham district, Alabama; second, the Wabana hematite deposits,

on and near Belle Isle, Newfoundland.

The great extent, commercial importance and scientific interest of

these Paleozoic interbedded iron ore deposits has long made them a sub-

ject of painstaking exploration and study; the extensive development of

them that has taken place during the last fifty years, and more especially

within the last ten years, has made it possible to gather together a large

amount of information of a detailed and accurate nature that under

other conditions would have been impossible.

Underground mining has largely taken the place of earlier open-cut

methods. At Wabana, for example, the ore is now being mined under

the sea at a distance of two miles from the original open-cut workings.

EARLE, INTERBEDDED IRON ORE DEPOSITS 117

In Birmingham and Attalla, Alabama; in Clinton, New York, and in

many other places, the same conditions prevail, and hard ore under-

ground mining has largely superseded the soft ore open-cuts.

Deep borings, in some cases nearly 2,000 feet in depth and several

miles from the present workings, have brought to light conditions un-

known in former times. Genetic theories, advanced originally from a

study of outcrops and open-cut mines, undoubtedly would have been

different, had the present data been available at the time. Yet with all

the data accessible at the present time and much literature within reach,

the question of the genesis of interbedded Paleozoic iron ores, and more

particularly the Clinton ores, is still in controversy. Men of established

reputation and wide experience adhere to theories sharply at variance

with one another. At least two and possibly three such theories are still

advanced and have the active support of men prominent in the mining

and geological world.

The practical importance of an accurate knowledge of the origin of

these ores must not be overlooked. Upon such knowledge depends the

interpretation of conditions underground below the present zone of

mining, the depth to which the ore may be expected to go and the con-

tinuance or change of richness of the ores.

It has been the purpose of the writer to include in this paper a brief

review of former theories and to discuss these theories in relation to re-

cent field and laboratory developments, showing where they fail to meet

certain conditions now known to exist and therefore must to some extent

be altered or superseded.

Further, the paper proposes and elaborates a theory of genesis which

the writer has worked out in the field and laboratory and which, in order

to separate from other theories and to avoid confusion, he calls the “Arte-

sian Replacement Theory.”

In brief, the writer attempts to maintain the following thesis: that the

Paleozoic interbedded iron ores of eastern North America, and more par-

ticularly the so-called Clinton ores, are replacements of porous strata of

ordinary mechanical sediments by iron oxide, the agency being ferrugi-

nous waters acting under artesian conditions.

ACKNOWLEDGMENTS

The writer wishes to acknowledge the criticisms, suggestions and as-

sistance given by Prof. J. Edmund Woodman, Dr. Albert B. Pacini,

Dr. Augustus Pacini, Prof. C. H. Smyth, Jr., S. W. McCallie, E. C.

Eckel, E. F. Burchard, Chas. A. Borst, Dr. E. A. Smith, Dr. E. O.

118 ANNALS NEW YORK ACADEMY OF SCIENCES

Hovey, Prof. A. W. Grabau, W. M. Bowron, W. C. Phalen, Prof. J. J.

Stevenson, Prof. C. P. Berkey, J. Bewley and H. V. Maxwell.

The writer made use of slides loaned by Prof. C. H. Smyth, Jr., in-

cluding those used as a basis for the sedimentary theory ; also slides loaned

by S. W. McCallie, State Geologist of Georgia, and a set of slides from

E. F. Burchard, of the United States Geological Survey.

The field work was provided for by a grant from the John Strong

Newberry Fund of the New York Academy of Sciences.

PART I. A STUDY AND CRITICISM OF PREVIOUS THEORIES

THE SILURIAN ERA

Whether the events that took place during the Silurian era were such

as could give rise to immense deposits of iron ore precipitated as original

material and thus forming contemporary sedimentary iron ore beds, or

whether fossiliferous limestones and sandstones of a nature favorable for

the later penetration of iron-bearing solutions were formed during a por-

tion of this era, cannot probably be determined without detailed study of

probable land and sea conditions at that time; but if any extended study

of these deposits is to be made, a knowledge of land and sea areas and. a

study of conditions that affected different kinds of deposits at the time

the inclosing strata were laid down seem not only desirable but important.

According to Dana, the North American continent at this time con-

sisted of a broad land area extending from Alabama northward east of

the present Appalachian system through Georgia, Tennessee, the Vir-

ginias, Pennsylvania and into New York, there turning westward, skirt-

ing the Great Lake region, then turning in a more or less southerly direc-

tion through a portion of Wisconsin, then abruptly turning northward

and running far into Canada. The southern and eastern portions of this

continent must have extended far out into the Atlantic ocean. On the

west, was a fast closing sea area shut off from the cold waters of the

arctic regions by rather extensive areas of the Archean shield. This left

an immense interior sea and a gulf or bay nearly 800 miles long, favor-

able to the presence of warm currents which undoubtedly greatly influ-

enced life in the waters and temperature conditions on the land. That

these conditions were responsible to a large extent for the texture, compo-

sition and distribution of the Silurian strata, we cannot doubt.

Quoting from S. W. McCallie (216. p. 162) :

“The region, however, of this tumultuous sea, with its rapid, moving cur-

rents, appeared to have been rarely of long duration. Scarcely had the deposits

EARLE, INTERBEDDED IRON ORE DEPOSITS 119

of sand and pebbles been fairly inaugurated, when the work was brought to a

sudden close by a deepening of the waters, or a change of sediments. The

enfeebled currents were now enabled to carry only the finest sands and clays,

the materials of which formed the innumerable layers of shale. The later

condition seems to have predominated throughout the entire Clinton epoch,

but the frequent occurrence of sandstone marks intervals of time and less often

repeated, the conditions favorable for the deposition of sands and clays gaye

place to conditions favorable to the deposition of limestone. The last named

conditions point to the clearing of the waters, and probably also the deepening

of the sea. The thinness of the individual limestone beds would indicate that

the conditions favorable for the deposition were of short duration. Yet, at

the same time, the extended area over which they often occur shows that the

conditions were widespread, and not confined to certain special localities. In

the entire series of Clinton rocks, from the beginning to the end, we here see

no evidence of sudden upheavals or tilting of strata. The character of the

sediment points only to general oscillations of the sea floor, many times re-

peated.”

At the close of the Clinton, no marked changes took place till the close

or near the close of the Niagaran period; then came a gentle uplift, as

shown by the erosional unconformities. This emergence continued well

into the Middle Silurian. Before the close of the Silurian period, two

more periods of elevation have been recorded.

The layers of sediment that formed a portion of the epicontinental

shelf at the close of the Clinton era thus emerged from their original

position and at the close of the Niagaran became a part of the coastal

plain, the layers of the Clinton formation outcropping and thus placing

their catch basins in a position favorable for the easy penetration of me-

teoric waters charged with iron-bearing solutions.

The following correlation table has been taken from Professor Grabau’s

work (128, p. 87):

Siluric: Upper or Monroan........... Hiatus and disconformity

Akron dolomite

Bertie waterlime

Hiatus and disconformity

Middle or Salinan..... ....-. Hiatus and disconformity

Salina.... Camillus

Syracuse

Vernon

Pittsford

120 ANNALS NEW YORK ACADEMY OF SCIENCES

Lower or Niagaran......... Hiatus and disconformity

Guelph

Lockport

Itochester

Clinton

(Disconformity refers to an erosional unconformity. )

The important points with reference to iron ore deposits to be deduced

from the above described conditions appear to be as follows: first, a thick

series of sedimentary beds of rapidly changing texture and composition,

clays and shales, sandstones and longer continued but less frequent lime-

stone deposits; second, an irregular shore outline with consequent effects

upon shape and size of sedimentary beds; third, a large area open to the

constantly changing waters of moving and probably rapidly moving

ocean currents from the south; fourth, to the east, land areas of the older

crystalline rocks of both acid and basic types, from which the iron salts

were dissolved in the course of weathering; fifth, a long period of slight

oscillations of the sea floor. After the deposits had been formed, they

were slowly elevated, and land areas were increased by a gradual emer-

gence of the sedimentary beds. No violent or pronounced folding took

place until the beginning of the Appalachian revolution, but mild dis-

conformities followed the slight uplifts accompanied by slight tilting.

Erosion of the strata on this coastal plain gave access on the part of

the ferruginous waters to the porous beds, in which the water soon devel-

oped artesion conditions.

Iron OrE Deposits OF THE CLINTON FORMATION

The Clinton iron ore was first discovered in or near the town of Clin-

ton, New York. It was found later to be very common throughout the

Upper Silurian, and the same type occurs also in other geological hori-

zons. It has been traced extensively throughout much of eastern North

America along the folds of the Appalachian system.

The Clinton ores are usually found interbedded with slates, shales,

sandstones and impure limestones.

TYPES OF ORE

The Clinton iron ores are known by various names according to text-

ure, composition and location.

The fossil ores (Plates VIII, IX, XVI) are composed of large masses

of marine fossils, such as bryozoans. corals, crinoid stems, brachiopods

and many other characteristic fossils of that age. These fossils are usually

EARLE, INTERBEDDED IRON ORE DEPOSITS 121

found in a very fragmental condition and have been wholly or partly re-

placed and coated and cemented with iron, or a mixture of iron oxide and

calcite cement.

The odlitic ores (Plates X, XX, X XI) are composed of odlites of hema-

tite cemented ‘together like the fossil ores, but containing the peculiar

odlitic structures which have often been referred to as resembling fish roe.

The odlites are made up of a nucleus of quartz or other mineral, coated

in concentric rings or spheres with iron, usually in the form of red oxide.

The flaxseed or “seed” ore is really odlitic ore and has the same pecu-

liar structure. In some cases, however, the term refers only to a smaller

grained odlite, such as that in Ohio and Wisconsin.

Dyestone ore is the name given to the Clinton red hematite of Ten-

nessee and some other regions because of the fact that it has long been

used as a paint or dye; and even in very early times it was mined in a

small way by near-by inhabitants for such purposes.

The red flux beds refer to a lean seam or seams of fossil ore in northern

New York, the highest iron-bearing seam of the New York Clinton

formation, and found typically at Clinton, New York.

Soft and hard ore are names used particularly for southern deposits,

to denote the difference between unaltered ore and that which, as a result

of weathering and a loss of soluble materials like calcite, has left a resi-

due rich in iron oxide and high in silica; the resulting soft ore being

rather more porous than the hard, and found at or within a few hundred

feet of the surface. The hard ore, on the other hand, is called hard, not

because of its actual hardness, but because it runs high in lime and has

not been affected by surface changes due to weathering. If we were to

dissolve the lime from hard ore, the result would be a residue rich in

iron and silica and precisely like the soft ores. Because of the value of

lime in fluxing iron ores, the hard ores of lower grade are much sought

and extensively mined. The soft ores, originally supposed to be the only

valuable ores, have been for the most part worked out; and the old open-

cut mines have given way to the underground hard ore mines.

EXTENT OF DEPOSITS

One of the most interesting problems to be solved in a study of the

origin of these iron ores is how any single theory of origin can account

for a line of deposits extending over such an enormous area. Following

the shoreline of the old Silurian land areas bordering the epicontinental

sea, we find deposits intermittently all along the line (Plate VII).

In Wisconsin, the ore occurs in Dodge County, attaining its greatest

#22 ANNALS NEW YORK ACADEMY OF SCIENCES

importance at a place called Iron Ridge. This Wisconsin deposit is iso-

lated and unlike the Clinton deposits found elsewhere, both in the shape

of the body which appears to have resulted from filling of a local basin,

and also in respect to the size of the odlites, which are smaller than the

oodlites found elsewhere and are peculiarly flattened. Professor Grabau

of Columbia University (128, p. 77) has suggested that they may be

wind-blown deposits in the nature of sand dunes, which have been buried

and later impregnated with iron ore.

The ore next appears in New York, beginning near Rochester, where

it can be seen in the Genesee Gorge in Monroe County, and then extend-

ing eastwardly through Wayne, Oneida, Madison and Herkimer Counties.

In this state, the ore is being steadily mined at Ontario and Clinton.

The most extensive development is that of the Borst properties, in what

appears to be a small bay of the old Clinton sea, covering possibly 2,000

acres near Clinton. Southward, we find the Clinton ores again outcrop-

ping in Pennsylvania. Here the deposits extend in a broken belt across

the central and southern parts of the state, including Montour, Snyder,

Juniata, Blair, Bedford, Mifflen, Centre, Fulton and Huntingdon Coun-

ties. These occurrences form a belt of several parallel ridges which run

‘southward into Maryland, where they appear in two beds in Allegany

County. The ore then passes into West Virginia, where it appears in

Mercer, Monroe, Greenbrier, Pendleton, Hardy and Grant Counties.

"These West Virginia deposits have been but little used or explored.

‘The ores are then found in a few isolated sections along a line passing

through the western part of Virginia and including Wythe, Giles, Bland,

Tazewell, Russell, Scott, Lee and Wise Counties. These deposits have

been worked tto a limited extent but are for the most part in a very unde-

veloped condition.

The ore belt then passes through Tennessee, extending across the entire

width of the state, a distance of over 150 miles, into Georgia. The Ten-

nessee ores occur in Claiborne, Campbell, Rhea, Roan, Sequatchie, Ham-

blin and Marion Counties. Here, owing to the much-folded condition

of the strata, many seams in parallel ridges appear running in a southerly

direction into Georgia. In Georgia, the ore is found in Dade, Walker,

Chattooga, Whitfield and Catoosa Counties. The ores of Dirtseller,

Gaylors, Taylors Ridges and Lookout Mountain all are of considerable

interest. ;

From Georgia we find the ore extending into Alabama, where it reaches

its greatest development in the Birmingham district. It is found in

Shelby, Tuscaloosa, Bibbs, Jefferson, Dekalb, Etowah and St. Clair

Counties.

EARLE, INTERBEDDED IRON ORE D#HPOSITS 123

Two other separate occurrences of this Clinton ore have been noticed.

One of them is a short spur extending from Kentucky into the southern

portion of Ohio. In Kentucky, it appears in Bath, Montgomery and

Fleming Counties. In Ohio, it is found in Clinton, Adams, Highland

and Muskingum Counties. The other occurrence, which is of no present

importance, is that of Missouri, where in Holt County a deep borehole

revealed a seam of fossil ore in what appeared to be Clinton strata.

From this outline, it is clear that these deposits are of great extent,

and that this feature must be reckoned with in accounting for their

origin.

OrHER Pateozotc DEpositTs

WABANA DEPOSIT, NEWFOUNDLAND

The Wabana deposit, one of the largest deposits of interbedded iron

ore in the world, is located on Belle Isle, in part, and extends for a con-

siderable distance under the waters of Conception Bay, Newfoundland.

The properties have been estimated to contain 3,635,000,000 tons of

hematite iron ore (170, pp. 745-752).

Conception Bay on the east is bounded by a shore of Huronian strata,

which overly an anticline of Laurentian age, but are not conformable

with it. The western shore of the bay is regarded as pre-Cambrian.

Between these shores is a great synclinal trough of sandstones, slates and

shales of Cambrian age. The upper strata forms Belle Isle and contains

six beds of hematite, two of which are being worked at present. They

show the following section (Symons; 328, p. 1009) :

Feet Inches

SLUG URES PES HA ce oad, CS RIC CROCE HELENE ORE TCE CEES mR eR roi 56

LMI AAO Meee eaters’ Sloss wire sheleh crate biata lettre eVeleurieuars ease, 2 1

SAMOStOM Garr mete G oheceore ole « Ciaeieta ee ee nitions waar e ekis 5 eye

15 Levene Ceseare Seto Polos CI IgCa cP Cece IGieRe chet Ais orcs aceon it 3

SAIL SUOM Cemeteries suciattteie: sickeyain eenekaral cia eieretmrecela wibees 2 Be

18 WebOeFeR oil ets Fy peek RCe MORE RCE Ric PEARARDL Er CRCAAY ick nc Rene re ence eae Pa 3

SAMASTOMES 22s ctace stools susie. otitl eins evan dicncyeieie..2 svetenete.it oe a:

1 8 ex OC ES EN eM ote co cxencar cd. Sect EL ROMER ICC CLT ER CPCI CEE SRE ee 3

SAM AISEOME mas Aeaysteeets see cleus olete ae Bioee chit Orel eibe ec austere 2 6

MOMMA GOR ee parcactevataetoi aici; « slenel Sis oro e cris eis ae ieee il B

Sandstone and shale........ Menetrsitiste ses eherecefete 3 :

Hematiter.. jis. He SOC Oe Oe edi sja weieiene. ae

Sandstone ....... aera seit seateesisaciate siete eteie! sya erereeie 46 ae

Hematite 2.0.5.0... eihereistee Siosts ake oh aycieucheie.o sit exe 9 A

SANASCONELANGESH WLOx.1 s crekersiecveier trereieiesere laine oon LOO “fe

Hema titerer cor teaie tete ce cae loool dec ddladecuecdlee 12 6

124 ANNALS NEW YORK ACADEMY OF SCIENCES

The ore consists of a dense red hematite, high specific gravity, with

bright metallic luster and a highly developed cleavage. The ore is of the

non-bessemer type.

These deposits are now being mined two miles from the outcrop, under

the sea. The quality of the ore has slightly improved with depth.

TORBROOK AND NICTAUX DEPOSITS, NOVA SCOTIA

Several beds of hematite of a similar type to the regular Clinton ores

have been located at Torbrook and Nictaux, Nova Scotia. The two

principal beds are the so-called “Shell” vein and the Leckie vein. Sec-

tions of this deposit may be found on page 147.

MIRA VALLEY DEPOSIT, CAPE BRETON, N. S.

The ore deposits of Mira Valley, Cape Breton, N. 8., are interbedded

iron ores much like the Clinton deposits. Professor Woodman in his

report (356, II-12—(3) ) says in reference to them:

“The iron-bearing minerals are magnetite, red compact hematite, specular

hematite, and possibly siderite in small amount. They occur in bands, inter-

stratified with the sediments. In places they grade imperceptably into the

latter across the bedding, and often downward or on the dip and longitudinally

or on the strike. . . . These ores furnish perhaps the best examples known

of partial and interrupted replacement.”

Section on McKinnon farm: Backes

Slate wm waillivcgs sre tee,s (sega eke sotete fore reroxthouekovels Mista peiae sreiele hisveais

REG SH EMALICC See sista 17 apotste be rojcuaia ar aie ate ce, o onete lava fe eee) cieie uaoualla fale 3.0

Sates An. iii s acceso sctarecotereis oles © atc larsdetNote eigio sve halal abies 1.5

QUMATETALE Riad Secale orate cous tesainvel nt hetaians leona elke ehectke tale elehereister ate ib

IMR MOTUS Es, arcane ieoreieateern Vere teabehe is far ciaimielsininne 'arbie wieterseanee 1.0

SST Gee eyes atctisy ze sestaoucsieh Pane ee au ares Cal erator fo mialrane alate leloiarevalsiotercts 0.5

SIDGOM EE eens cclevohie sil sete recclotele aiaichastansin’D cade once char crone ne ote

OREN raat 14 er AI NRE Pe RENAE ESATO ARTS EB tone aD hrs oe ecg hac 1.0

(STEN EUCAILRE Aetna ORO DE DIG COG COD OORT IC oO GrO Cod Maer or 2.0

SIH ESAAS oo. BO aCe RG Rule Eon tC ODICLOIE OCr Sta Oo On Dodc 1.0

TOF eyes eho eran a ei oick clolekorcvct si wet ® cuscteaus, 6 eabtavetovaun eievetere ererenete 10335)

STATON re eicteketenhs sie cha ature aPelay a sreravatcue ty tote oraiare a tionaeiees

SUMMARY OF THEORIES OF GENESIS

The origin of the Clinton ores has long been the subject of dispute,

and even to-day, with the large amount of data available, we find con-

siderable diversity of opinion. Mining men, owners of mines and those

EARLE, INTERBEDDED IRON ORE DEPOSITS 125

interested in the financial success of the various properties naturally

lean for the most part to the theory that will best support their conten-

tion that the richness of the ore body will not diminish with depth. The

views maintaining this contention seem to be well sustained in certain

places by some of the facts developed in the course of actual mining

operations. In other localities, however, data appear to contradict this

view to some extent.

A theory which would apply to all of the Clinton deposits must ac-

count for the odlitic character of some ores and the fossiliferous charac-

ter of others, for the occurrence of the ores in conformable strata, for the

difference in lime and silica content in the various ore beds and within

the same bed, for the presence of waterworn pebbles and grains of sand,

for the soft and hard ores so common in the southern localities and for

the compact and cleavable ores of some of the northern deposits. To

find a theory that will reconcile all of these variables has thus far been

impossible, and most writers have admitted that to a limited degree

other theories besides their own may have some value.

Three principal hypotheses have been advanced to account for these

Clinton ores: (1) the theory of original deposition, which has been

referred to as the sedimentary theory; (2) the residual enrichment

theory; (3) the replacement theory. Of these theories, the first has the

greatest number of advocates. It has the merit that depth would not

affect the value of the deposits.

PRIMARY DEPOSITION

The advocates of the primary deposition theory believe that the Clin-

ton ores were deposited contemporaneously with the inclosing rocks, i»

the form of chemical precipitation at the bottom of the sea. Some

claim that the iron was originally dissolved from the ancient crystalline

and metamorphic rocks of Appalachia Land. 'The ferruginous waters

were carried into inclosed or partly inclosed shallow seas or basins. The

iron salts were slowly oxidized and precipitated gradually, forming con-

centric layers of iron about particles of sediment on the sea bottom. As

the sediments varied in kind and texture in different places and at dil-

ferent times, the nuclei about which the iron concretions were formed

differed. In some layers, the odlitic structure surrounded grains of well-

rounded quartz sand; in other layers, broken fragments of fossils such as

crinoid stems, bryozoans, brachiopods or corals were inclosed in iron

concretions. It is claimed by some that where calcareous fossils were

present, some replacement occurred, but only while the Sri: of original

sedimentation was in progress.

126 ANNALS NEW YORK ACADEMY OF SCIENCES

The advocates of this theory are numerous. In order to set forth the

arguments given in favor of this theory, the writer quotes from several]

of its leading advocates.

Quoting E. C. Eckel (37, pp. 32-33) :

“The principal facts supporting the theory of sedimentary origin may be

briefly summarized as follows: bah

“1. In mining from slopes running down on the dip of the ore bed, when

once the limit of surface weathering is passed—and this may be at any point

from 1 to 100 feet below the outcrop—no further important change in the ore

is found with increasing depth; though a number of mine workings are now

close to 2,000 feet from the outcrop.

“2. A number of borings in Alabama have struck the ore at points from one-

half to one mile back from the outcrop, and at depths of 400 to 800 feet below

the surface. The ore encountered in these borings was hard ore of the usual

quality, and not merely a ‘ferruginous limestone. Several borings in New

York have struck Clinton ore at distances of from 10 to 15 miles back from

the outcrop. These borings showed good ore at depths of 664 to 995 feet below

the surface.

“3. The physical character of the odlitic ore cannot readily be explained on

any replacement theory, while the formation at the present day of original

oolitic materials is a matter of common knowledge.

“4. The occurrence of fragments of the ore in overlying beds of limestone

in the Clinton formation as described by Smyth, points to the fact that the

ore had been formed prior to the deposition of this limestone.

“5. If the replacement theory were accepted, one would expect that the ore

beds would show a greater vertical range; that is, that they would at places

occur in rocks of other than Clinton age. Throughout their entire extent, the

Clinton beds are closely associated with Silurian and Devonian limestones and

shales, some of which offer excellent receptacles for the replacement deposits,

but the characteristic red ores are confined to the Clinton itself.”

The author goes on to say that primary replacements did not exist to

any great extent, but, although no definite proof has been found, it is

probable that some secondary replacement has since taken place. Leach-

ing, of course, is noted. Eckel has done a very considerable amount of

work on these ores while engaged in the economic work of the U. 5.

Geological Survey, and, although his principal investigations were upon

the deposits of the southern states, he included a wide extent of Clinton

deposits in his special study, and his views must be recognized as founded

upon accurate information and a broad knowledge of the literature

available.

According to Professor C. H. Smyth, Jr. (317), the replacement

theory for the origin of the Clinton ore was not substantiated by the

facts in the field. The caleareous rocks would certainly have caused the

iron to be precipitated while it was passing through them, yet the ore is

EARLE, INTERBEDDED IRON ORE DEPOSITS 107

found in places directly underlying limestones and shales. Concretions

in the lean ore were found to be as ferruginous as those found in the

richer ores; accordingly, the substitution took place before the fossil

fragments were consolidated into a bed by the cementing material. If

the ore is formed by a process of replacement, it should contain some

ferrous carbonate, yet this has never been found. The iron did not come

from above, for the Clinton ore beds are often horizontal, with no chance

for the action of downward-circulating waters. There is no doubt that

the ore was laid down in the form of an original precipitate at the same

general time that the inclosing sediments were deposited. It is likely

that there has been some enrichment of the deposits by the removal of

calcium carbonate. The iron is secondary only in respect to the organic

fragments, but primary with respect to the ore deposits as a whole.

Weathering has contributed to the present condition of the formation as

we find it to-day in some localities. Iron oxide and silica were deposited

together from solution in meteoric waters. Organic material caused the

retention of the iron in such waters. There is a connection between

silicic acid, iron and organic acids in the soils, and a deposition of iron

and silica together. Odltes were not originally calcareous.

Smyth has probably been quoted more than any other writer in sup-

port of the sedimentary theory of origin. It is certain that the careful

microscopic work done by him is well worthy of careful consideration

before coming to any final conclusion in regard to the origin of these

deposits. Most of Smyth’s work was founded on a study of the Clinton

ores of New York.

Quoting D. H. Newland and C. A. Hartnagel (234, p. 50):

“The evidence in support of both views has been traversed very thoroughly

by C. H. Smyth, Jr., in a paper which represents as well the results of long

experience and close study of the Clinton ores both in northern and southern

districts. There can be no doubt after an impartial perusal of Professor

Smyth’s paper that the theory of sedimentary origin is fully substantiated for

most of the occurrences. For the ores under present consideration. this is the

only explanation at all compatible with the conditions.

“The stratigraphic features presented by the New York section of the Clin-

ten do not lend themselves to the conception of vertical circulations of ground

water such as would be required to dissolve and carry iron from the overlying

strata. The ore beds everywhere lie nearly horizontal; their dip is universally

toward the south, at an angle no greater probably in many places than that

given by the contour of the original sea bottom on which they were deposited.

At no time in their subsequent history have they been steeply inclined. More-

over, they are overlain by thick shales not readily permeable to water. Under-

ground flowage must necessarily be limited and be dependent for the most

part on the cropping out of the more porous strata-like limestone and sand-

stone layers. Thus it is directed rather along the bedding planes than across

128 ANNALS NEW YORK ACADEMY OF SCIENCES

them. Below the ore, there is also more or less shale intervening before the

top of the sandstone and conglomerate basement is reached.”

G. P. Grimsley (130, p. 74):

“The rocks of the Clinton series in this state are shales, clays, sandstones

and an absence of limestone. If there was originally a bed of limestone now

replaced by ore, the stratum was a very irregular one, varying in thickness

from 6 inches to 5 feet. It expanded and contracted from place to place in a

most irregular manner; a relation very unusual for limestone, but often present

in sandstones and other shallow water rocks. By the theory of original sea

deposition of this iron ore, it would be formed in the Clinton sea in the same

manner as sandstones and shales. The iron was precipitated and mixed with

sand and clay in which fossils were preserved. The odlitic structure would

imply a concretionary deposit, the iron ore being precipitated around sand

grains in concentric form. In some portions of the sea, as in the Keyser area,

there was only a slight precipitation of iron in the sand.

“The difficult factor to account for in this theory is the quantity of iron

available for this deposit in the Clinton sea, apparently not duplicated at any

other time before or since. There must have been at this time an exceptional

quantity of iron present; its source is difficult to explain. There are thus

encountered in both theories factors almost impossible to account for; but it

seems to the writer that the theory of original deposition offers a more satis-

factory explanation of the origin of these West Virginia Clinton ores than

that of replacement.”

One of the most complete publications on the Clinton ores has been

made by S. W. McCalhe (216) for the Georgia Geological Survey. He

agrees with Eckel and Smyth in placing the origin as original sedi-

mentary deposition, but differs from them as to the source of the iron.

He maintains that it came originally from large deposits of glauconite

marl.

Both J. S. Newberry (282) and T. C. Chamberlin (53) conclude that

the Clinton ores of their states were formed by original deposition of

their iron content, similar to the Swedish lake ores.

H. D. Rogers (290, p. 729):

“The regular ores of the Surgent (Clinton) series are to be regarded as

among the permanent constituent strata of the formation, and as having origi-

pated with other sedimentary materials in the form of very extended, but

thin, sheets of ferruginous matter, covering at successive epochs the wide floor

of the quiet Appalachian sea.”

He goes on to say that the source of the oxides has not been deter-

mined. He acknowledges that much secondary enrichment has taken

place by enormous quantities of ferruginous matter diffused in marls,

slates and shales in contact with the ore bodies, being dissolved in the

form of sulphate and then redepositing the iron in the ore beds, reaction

EARLE, INTERBEDDED IRON ORE DEPOSITS 129

with the lime of fossils converting it to peroxide. This secondary en-

richment is plausible because where the outcrop, the slope of the ground,

the thickness of the overlying strata and other conditions are favorable

to considerable infiltration of surface water, the ore carries a higher

amount of iron than at less favorable places. The fossils often form

one-half of the total weight of the ore; it is obvious that if part of the

lime thus contained is dissolved out, the remaining peroxide of iron will

form a much larger percentage of the total bulk of remaining material.

SECONDARY ORIGIN

Residual Enrichment Theory

The residual enrichment theory starts with the supposition that the

ore beds were originally limestones rich in iron, that by a process of

leaching the hme carbonate was partly or wholly removed, and that the

iron, together with the insoluble material, was left in a much more con-

ccentrated form.

Similar effects are known in tropical countries; in Cuba, for instance,

where silica by a process of weathering known as laterization has been

removed from iron-bearing rocks, leaving the iron and insoluble portions

rich enough to be classed as an ore and mined profitably.

I. C. Russell (292, pp. 22-23) :

“Portions of the Silurian rocks of Alabama, readily recognized as limestones

when unweathered, are easily mistaken for sandstones and shales when only

their weathered outcrops can be seen. The Clinton ore, or fossil ore, inter-

bedded with strata of shale and sandstone forms one of the most character-

istic beds in the Upper Silurian rocks of Tennessee and Alabama. In the

mines of Gadsden and Attalla, Ala., where Clinton ore is worked, the strata

are highly inclined (a dip of 70 to 80 degrees to the southeast prevailing) and

well exposed for study.

“The outcrops of the beds are soft, porous, highly fossiliferous ore, which

has a deep brownish red color, and is easily worked and easily smelted. The

ore at Attalla retains this character to the depth of about 250 feet, measured

down the slope, and then changes to a hard, compact, ferruginous limestone,

rich in fossils. The marked difference in the character of the ore in the upper

portions of the mines as compared with that of the lower portions is due

entirely to weathering. This is shown by its chemical composition. Two

typical samples of the ore, selected by me—one from near the surface, repre-

senting the ordinary character of the soft ore, and the other from a depth of

‘250 feet, representing the hard ore, but not the most calcareous variety—gave

on analysis the following percentages of iron, lime and carbonic acid, after

‘drying at 105 degrees Centigrade:

At surface 250 feet

ESS CSS S DDC ORES UREOS Ces SCT ee 57.52% 7.75%

(GEIO) excel aig Grd SPOS BIG OIC EROS PRICE RES 1.38% 47.64%

rare e tiers Marana te, shevavorn el axe \jo,0 6)9/ eel oc) 0: .80% * 34.90%”

130 ANNALS NEW YORK ACADEMY OF SCIENCES

Eekel (37, p. 33) claims that Russell was mistaken and that the At-

talla ores do not vary with depth.

Replacement Theory

The replacement theory holds that the iron content of the Clinton

rocks in the form found at present has resulted from a replacement of

lime carbonate by iron, long after the rocks had been deposited. The

iron was introduced by descending waters charged with iron which they

had dissolved out of overlying ferruginous rocks.

J.J. Rutledge (293, pp. 254-255) :

“The conclusion that the iron content of the Clinton iron ore beds of Stone

Valley, Penn., is due mostly to replacement by removal and enrichment, seems

unavoidable, when it is considered that but a portion of the fossiliferous lime-

stone or of the hard ore is found to contain iron oxide when examined in thin

sections under a microscope. Calcite cement makes up by far the greater

portion of the section.

“An analysis of the limestone shows that it contains but 2.12 per cent of

FeO and 2.35 per cent of Fe,O,. These seem much too small an iron content

to yield as rich an ore as the soft ore, simply by the removal of the calcium

carbonate. Field conditions such as the occurrence of weathered shales, dull

colored clays and iron-stained sandstones, prove that the action of replacement

is still going on.

“The iron came originally from the overlying shales and was transferred

later to the beds of fossiliferous limestone.”

The following reasons are advanced by Rutledge for the statement

that the addition of iron was not due merely to the removal of the lime-

stone, as would be the case under the enrichment theory :

“(a) The character of iron ore concretions where associated with silica.

“(b) The invariable association of the soft ores (rich) with the leached,

decolorized shales and the hard (lean) ores with unweathered, bright red

shales.

“(c) The relations of the ores to the shattered sandstones and to the topo-

graphic situation of the ores.

“(d) The fact that analogous replacements are now going on in the Medina

formation.

“(e) The observed progressive steps in the transformation of the limestone

to an ore, which may be followed in the field, in the sections under the micro-

scope and in chemical analyses.

“(f) The absence of conditions such as local crumpling, including a shrink-

ing of the strata, pointing to a relative rather than an absolute enrichment

of the ores.”

I. C. White (198, pp. 135-137) :

“The iron has evidently been filtered into the bed as the lime has been:

EARLE, INTERBEDDED IRON ORE DEPOSITS 131

filtered out of the bed, otherwise the percentage of iron in the bed would not

diminish below drainage level.

“Wherever the ore is valuable the inclosing rocks are very much weathered ;

the lime rocks are changed into clay and the shales overlying the ore are

bleached almost white; their iron having presumably been transferred to the

ore bed. And this is a reasonable way of explaining the fact that the ore bed

does not always keep the same place in the series, for any bed can become an

ore bed, provided it is so situated as to be a water-bearer and recipient of the

iron-leachings.”

A. F. Foerste (110, pp. 28-29) :

“As a rule the iron has replaced the substance of the bryozoan itself; all

the stages between partial and complete replacement may be noticed, the most

complete stages being of course found in the purer ores. Usually, correspond-

ing changes are observed in the cement which binds the o@litic grains together

into a solid mass. It is evident in these cases that the origin of the odlitic

structure is not due to a concretionary segregation of iron particles, but finds

its explanation in the gradual replacement of the lime of the fragmental fossil

bryozoans, particle by particle, by the iron ore.”

N. S. Shaler (303, p. 163) :

“The ores were not included in the present iron-ore beds at the time of their

deposition, as conditions varied so much at different points that this would

have been impossible. The ore-occurrences are due to replacement of limestone

beds by iron-bearing solutions derived from overlying shales. The iron could

not have been deposited as far from the shore as the limestones were.”

J. P. Kimball (190, p. 355) :

“Parts of thin fossiliferous limestones of the Clinton group of strata are

often replaced by red and brown ferric oxides from extraneous sources.

“This replacement has been wrought especially in steep dips by infiltrations

from drainage of adjacent ferruginous strata, partially of an inferior series

outcropping topographically higher in the flanks of these parallel ridges.’

APPLICATION OF RECENT INVESTIGATIONS

THEORY OF ORIGINAL SEDIMENTATION

Even though it may be demonstrated that the odlitic hematite can be

successfully synthesized in a chemical laboratory in open agitated water ;

even though odlitic formations such as the sand of the Great Salt Lake

in Utah and the brown iron odlites of the Swedish lakes are being formed

in open water to-day; yet no matter how plausible the theory may be in

most respects, if a single factor prevails that would be impossible under

conditions necessary for original deposition of the iron ore beds, it is

132 ANNALS NEW YORK ACADEMY OF SCIENCES

enough to discredit the correctness of the sedimentary theory and to

force us to look elsewhere for an explanation of the origin of these forma-

tions.

Sedimentary Aspect of the Ore Beds

That the general appearance of the ore beds would give the impression

that they must be regular sedimentary iron-ore beds laid down as the

advocates of sedimentation suggest, cannot be doubted. Clean contacts,

lens-shaped deposits, widespread occurrence, separated individual iron-

coated odlites, non-ferruginous sandstone and limestone beds overlying

some of the ore beds and underlying others, all would tend to give weight

to the sedimentary hypothesis. Before the theory can be considered as

proved, however, it must account for certain conditions that appear to the

writer irreconcilable with any theory based upon original deposition.

Consequences of Sedimentary Theory

In the first place, let us apply the sedimentary theory to the odlitic

hematites that are so common in New York, Virginia, West Virginia,

Kentucky, Ohio and Wisconsin. Under the sedimentary theory, it is

assumed that the Clinton Sea was heavily charged with iron salts in solu-

tion, and that, as sediments were being laid down along the shallow and

gently inclined shore slopes, myriads of sand grains under the influence

of considerably agitated waters were coated with layer after layer of

iron oxide, which in many cases alternated with silica. These iron-coated

grains finally accumulated into beds in the same manner as any sand

stratum would accumulate and were then cemented by more iron and

calcite into solid beds or layers of sedimentary rock like any other sedi-

mentary deposit.

For the sake of argument, let us assume that such conditions did exist.

If the sea-water contained enough iron in solution successfully to coat

grains of sand until they formed a bed several feet in thickness, would it

not be reasonable to suppose that all sediments laid down simultaneously

would be coated, impregnated or at least stained with iron? Would not

all lenses of clay and shale and limestone be completely saturated with

the same iron-bearing sea-water that coated the mass of odlites? Would

it be possible for any portion of the shore deposits along the entire length

of the Clinton Sea to have escaped without leaving permanent evidence

of the presence of such large quantities of iron in solution in the sea-

water—iron sufficient to cause deposits within a comparatively short

period extending for nearly two thousand miles along the shore, many

miles out to sea and in some cases many feet in thickness?

EARLE, INTERBEDDED IRON ORE DEPOSITS 13

Field Evidence

In a small seam of odlitic hematite about eight inches in thickness

located at Big Stone Gap, Virginia, the writer discovered what at first

appeared to be a small bowlder (Plate XI, fig. 1) entirely surrounded by

iron odlites. Upon removing the stone and breaking it, he found that

instead of being an ordinary bowlder, it was an original formation, such

as is often present in beds of loose sand that have been penetrated grad-

ually by mineral-bearing solutions and consolidated by the well known

process of cavernous consolidation, leaving loose sand-filled cavities (Plate

XI, fig. 1). The “bowlder” was well filled with practically pure loose

quartz sand, with no iron-coated or hardly even iron-stained grains (Plate

XI, fig. 2) and was merely the first of several also similarly sand filled.

Here we have a local accumulation of sand made up of quartz grains

entirely surrounded by iron-coated odlites, yet completely ignored by the

iron-charged solutions and not even consolidated. A little farther on in

the same seam,:another small mass of yellowish white sand was found,

which was partly consolidated but had not been penetrated by the solu-

’ tions that coated the surrounding odlites (Plates XII, XIIT).

If we still believe that the iron-bearing solutions were a part of the

sea-water, how can we explain two sets of different consolidations, one

with iron the other without iron, from the same source and at the same

time as the surrounding conditions seem to indicate in this case? Let it

be emphasized that these occurrences are situated not at margins of ore

seams, but well within a distinct stratum of hematite.

In Clinton, New York, in a single hand specimen, the writer found

odlites coated with iron oxide and other odlites coated with a green min-

eral in concentric layers (probably an iron silicate, greenolite) and still

a third type of odlite composed of a quartz nucleus, then a ring of iron

oxide, then a thicker ring of the green mineral and finally another ring

of iron oxide. In a seam in Birmingham, Alabama, a single slide of the

Clinton ore shows a calcite-coated odlite and an iron-coated odlite side by

side. How would it be possible for the iron-charged sea-water to distin-

guish between different grains of the same mineral and coat one with one

substance and its neighbor with an entirely different mineral ?

At Niagara gorge, we find the Clinton series of limestones, shales and

sandstones, but no evidence of iron-ore seams. This indicates that the

iron-bearing marine solutions had suspended operations at this point, and

yet had been active as far west as Ohio, Wisconsin and Holt County,

Missouri.

Finally, in applying the sedimentary theory to the fossil-ore beds, we

134 ANNALS NEW YORK ACADEMY OF SCIENCES

find conditions similar to those prevailing in the odlitic strata; limestones

untouched by iron-bearing solutions, but with overlying and underlying

iron-ore seams; lenses from a few inches to many feet in length composed

of limestone with only a slight marginal penetration of the iron, and yet

entirely surrounded by iron ore (Plate XIV, fig. 1). In places, fractures

in the limestone beds have been penetratéd, by iron and the walls of the

breaks lined with ore. In other occurrences, the iron has followed seams

or laminations in the limestones and has replaced the limestone along

these planes of weakness (Plate XV).

A generally prevailing condition of apparent replacement in all stages

is found in both fossiliferous and odlitic beds, in which both calcite and

quartz show corrosion and replacement (see photomicrographs, Plates

ROWE KORY KOR)

Inadequacy of Sedimentation in Open Sea

The conclusion seems justified that, whereas widespread similarity of

conditions should be expected, with unbroken evidence of the presence of

marine iron-bearing solutions in the sedimentary beds (whether of sand-

stone, limestone, shale or clay), yet the reverse conditions actually exist,

for (1) small lenses of loose sand untouched by iron-bearing solutions

are found, which, under the conditions imposed by any sedimentary

theory, could not have been free from the iron; (2) two unlike consoli-

dations, one without iron, the other surrounding the first and completely

charged with iron—a circumstance that would have been impossible

under the sedimentary conditions pointed out by the various advocates

of marine deposition of iron ores; (3) differently coated odlites in the

same immediate locality would hardly seem possible under such a theory ;

(4) the penetration of iron into seams, lamination planes, weakened

strata, mudcracks and fissures running off from the main ore beds could

hardly be explained under theories depending upon a primary origin of

the ores. |

Sedimentation in Lagoons

In regard to a growth within inclosed lagoons or basins of shallow

water, the field evidence in some places may bear this out. The writer’s

observations, however, have seemed to show much active wave erosion and

considerable rather violent agitation of the sea-water. This is illustrated

by what appear to be two well-formed stacks which could only have been

shaped by wave erosion; one at Clinton, New York, and the other at Red

Mountain, Birmingham, Alabama. Further evidence might be suggested,

as, for example, the existence of several kinds of varieties of coral which

EARLE, INTERBEDDED IRON ORE DEPOSITS 135

do not thrive in the still waters of inclosed basins but require agitated

waters in the open sea. In places, also, the sediments contain a large

amount of water-worn material, fossils badly broken and coarse-textured

conglomerates. So, although we do see in places such testimony as Pro-

fessor Smyth (317) has suggested, yet we find also much evidence of

quite different conditions; and, therefore, it seems to the writer that

httle importance can be attached to the supposed basins as an aid to the

determination of the origin of these ores.

THEORIES OF REPLACEMENT AND SECONDARY ENRICHMENT

Persistence of Ore Seams

The question of depth and distance from the outcrop to which the ore

is known to extend is an interesting one, and the facts are inconsistent

with the theories of secondary enrichmefit and replacement, where such

theories depend upon leaching of slates and shales or vertical descent of

ground waters. One boring has shown good ores, 1,902 feet deep and

two and one-half miles from the outcrop; another over 800 feet deep and

more than ten miles from outcrop and with a very low dip. The writer

is inclined to agree with Professor Smyth (loc. cit.) in part in regard to

such data; but as to using this great depth as an argument in favor of

original deposition, he cannot convince himself that it applies. Some of

the deposits in that event must have extended into waters of very con-

siderable depth and distance from shore; and as depth increased, the

amount of iron necessary for keeping up the same degree of richness as

nearer to the shore must have been great indeed. It would seem highly

improbable that these iron-bearing marine waters could circulate over

and through the sediments without becoming diluted in the great expanse

of water, as currents carried them far out to sea. The present writer

would, on the other hand, lay claim to the argument of great depth in

support of his ideas of origin, which differ widely from those of the advo-

cates of original deposition.

Unreplaced Limestone

Finally, as to the argument that some overlying beds of limestone

would be excellent for replacement of lime by iron and yet remain prac-

tically untouched with clean-cut contacts although in close proximity to

iron-bearing seams. Here again the writer agrees with Professor Smyth

that the facts are against the replacement theories as ordinarily ad-

vanced, especially since many layers of impervious rock lying in a more

or less horizontal position intervene between the ore seams and the sur-

136 ANNALS NEW YORK ACADEMY OF SCIENCES

face. Yet the writers own conception of the origin of these ores is

much strengthened by these same conditions, which are indeed neces-

sary, according to his ideas, for the existence of the iron-bearing seams.

Because of these conclusions, it seems unnecessary to the writer to spend

further time on a theory that in the hght of such conditions as have

been pointed out seems not only inadequate but impossible.

Secondary Enrichment Theories

Under the head of secondary enrichment may be classed both enrich-

ment due to replacements and that due to residual enrichment. Of the

theories of secondary origin, some depend upon leaching of soluble mat-

ter and a consequent enrichment of the iron-bearing deposits because of

relative insolubility of the iron, and others upon a combination of re-

placement with enrichment by a process of leaching of iron from over-

lying ferruginous shales and slates and replacement of the lime in the

underlying limestone by iron thus obtained. The most that can be said

regarding these possibilities is that undoubtedly these alterations have

been made, but to a very limited extent, and such methods are wholly

inadequate to explain the distribution of the ore, as shown by recent

borings and extensive underground mining, which have proved that hard

ore does not change materially with depth, and that the above theories

only account for the very superficial facies called soft ores. Absence of

extensive exploration gave these theories plausibility and caused much

favorable comment upon them for a time, but more recent underground

mining has caused them to be more or less generally discredited.

Simple Replacement Theory

We still have one well recognized theory to discuss before advancing

the theory of the writer, and that is simple replacement. ‘The advocates

of this theory have seen extensive evidence of replacement of the calcite

by iron in the fossiliferous beds and have noted the replacement of the

lime cement by iron. In respect to the evidence advanced by these au-

thors, the writer is inclined to believe that to a large extent it is correct,

but in a few particulars he finds himself obliged to disagree with their

deductions.

The first is the attempt to account for the iron as a leached product

from overlying shales. It seems incredible that such immense quanti-

ties of iron can have been derived from so limited a source. It also

appears, as Professor Smyth has well stated, that the intervening layers

of limestone which are comparatively free from iron would have offered

EARLE, INTERBEDDED IRON ORE DEPOSITS 137

an excellent field for progressive replacement, whereas we find more or

less clean-cut contacts and underlying rich iron ore beds. A second

point of disagreement is in relation to the direction of movement of the

iron-bearing solutions under these theories, which, in the various papers

examined, seems to be by vertical descent of ground water, often limited

in depth to a few hundred feet. Thus I. C. Russell (292) refers to a

case in Attalla, Alabama, in which the ore changed to ferruginous lime-

stone within a few hundred feet of the surface.

PART II. ARTESIAN REPLACEMENT THEORY

ARTESIAN CONDITIONS

CONTROLLING FACTORS

Artesian conditions result from a natural arrangement of strata in

such manner that they act as a retaining basin or catch basin in porous

strata in which water is or may be confined under hydrostatic pressure

sufficient to cause the water to rise when the reservoir is tapped.

The conditions requisite for the existence of artesian wells, as set

forth by Chamberlin (54a), are the following:

1) A porous stratum for the penetration of water ;

2) An impervious underlying layer to prevent the downward escape

of water ;

3) An impervious overlying layer to retain the water under pressure ;

4) An inclination of the layers, at least in part, so that the point of

entrance is higher than any other portion of the retaining layers;

5) A reasonably large exposure of the porous layer, in order that free

entrance may be provided for the penetrating waters ;

6) Sufficient rainfall for water supply ;

7) Absence of any place of escape for the retained water.

This summary of the usually quoted factors may be taken to indicate

ideal artesian conditions, but many variations may exist and still allow

artesian flow, although these requisites or adequate substitutes for them

must be present.

The pervious medium may be any crystalline or sedimentary non-

crystalline rock or stratum which contains enough pore space to permit

a circulation of the penetrating water. Sandstones (particularly of

coarse texture), fossiliferous limestones and even in some cases coarsely

crystalline limestone may serve as a carrier and saturation medium for

artesian waters. In some instances, even bedding planes, laminations

or fracture systems may be adequate.

138 ; ANNALS NEW YORK ACADEMY OF SCIENCES

The impervious floor is not absolutely necessary. In some cases, arte-

sian flow might be expected if the underlying layer, although penetrable,

was less porous than the middle layer, so that the incoming water would

accumulate with greater rapidity than it could escape downward. This

would occur in the case of the two sandstones of marked difference in

texture, the upper coarser and the lower finer.

The impervious layer above is more essential, but even here extreme

differences of texture may give some results, even though the overlying

layer is somewhat porous. It must be remembered, moreover, that poros-

ity is relative and that absolutely impervious strata are unknown.

Another very important consideration with reference to these porous

and impervious layers is the possibility of accumulations by precipitation

or by the mechanical fillmg of voids at or near the line of contact be-

tween the strata. If, for example, two sandstones, one coarser than the

other, are in contact, precipitation would first occur near the contact in

the pore spaces of the finer textured rock, as there the penetrating solu-

tions would move with less freedom and rapidity.

Mechanical sediments as well as mineral crusts might be expected to

play some part toward establishing more complete artesian conditions.

Circulating ground waters, following lines of least resistance, tend to

establish more or less definite channels, and if these channels are fairly

well retained, nature itself will attempt to improve conditions by steadily

increasing the density of the carrying medium through cementation and

other processes of filling the minute channels of escape.

Inclination of artesian beds is necessary only for the purpose of allow-

ing gravity to establish hydrostatic pressure. If the water head is suffi-

ciently high to develop enough pressure to overcome the friction and

other causes of retarding a free flow of water, it is fair to assume that

artesian waterways may exist in practically horizontal layers, the move-

ment of the water depending upon the amount of pressure exerted by the

water column.

The absence of an avenue of escape may be accounted for in many

ways; for example, a marine slope may be terminated at the lower end

by a change of texture from coarse to very fine, as sand to mud; or pre-

cipitation may take place at the lower end of a runway, thus filling the

voids in the previously porous layers.

CIRCULATION OF ARTESIAN WATERS

It has been suggested that artesian water is stagnant until tapped;

but the writer is inclined to believe that absolutely stagnant artesian

waters would be unusual if not impossible.

EARLE, INTERBEDDED IRON ORE DEPOSITS 139

In the first place, any leakage, even though very slow, would promote

circulation in the inclosed waters ; artesian conditions depend upon rela-

tive, rather than absolute, imperviousness.

In the second place, differences in temperature would cause the estab-

lishment of currents involving a more or less constant circulation. That

such differences of temperature do exist between the surface waters at

the outcrop of the porous layers and the waters confined at considerable

depths is hardly open to question. ‘The density of cooler water is greater

than of water at higher temperatures, and therefore such water would be

acted upon by gravity, causing the denser water to sink while the less

dense would rise.

In the third place, dissolved salts would add to density of the waters,

and if solutions heavily charged with iron salts were admitted to the

artesian runways, they would tend to sink until by precipitation they

lost a part or most of their load, after which they would tend to rise and

give place to other charged water from above.

Fourth, waters charged with insoluble mechanical sediment would

tend to sink and set up circulation within the runway.

Fifth, oscillating movements of the water would occur because of tidal

variations in load, accession of fresh surface water, crustal movements

and other minor causes effecting changes of pressure transmitted in

various ways, such as through the overlying impervious layer or through

the water in the reservoir.

Slowly moving waters thus act as carriers of iron salts and other min-

erals and gases and precipitate much more readily because of relative

confinement and slow method of circulation.

TYPICAL SECTIONS OF CLINTON ORES

MISSOURI

Holt County. Drill hole. Red odlitic hematite of Clinton age, 1,885

feet below surface, showed the following section (Crane, 66) :

Feet Inches

Rurple shales) GimperviouS)inccseues se eece oes 21 3

Oohtiewhematiten(POrous) esos soe olen oe 3 8

Earthy argillaceous hematite................... es 5

Light green sandy shale (impervious).......... 2, 6

Bluish green shale (impervious)............... 64 9

ALABAMA

In the Birmingham District, out of about 80 sections extending over

forty-two properties, seventy-two included ore seams either fossil or

140 ANNALS NEW YORK ACADEMY OF SCIENCES

odlitic with shale or slate directly overlying and underlying the ore beds.

These seams included the Ida, Big and Irondale, besides many too small

to be of practical importance. (For sections, see Eckel, 37, pp. 74-78.)

Section East No. 2 mine, Red Mountain (Phillips, 266, p. 64) :

Feet Inches

GClaty amdSoOile vse «cre ete sst svete larseevekerens me tatoystottevenetehs 6

SAMAUSTOME) A airsysotererole cueterete sseketondistercte eiac S etchevsieve’ss 3

CU BI ss reid foie: SR syste garenend © otiekatete: stalel ovoneieye sa: o eke etekoreneh mye i

SANGUSTOMEINSS ai srcpons s sisnet olors, shshelerenero etereseilorsiere iol ete feuehere 1 as

Cy so oie Sees i otenstotaneredo te lavercteve mucherste Coleus cele isiees eiciews =e 2

ORG aah sco) Rae enter Cee aie eT eh teres Cee ere ate 6

CUA Reta ecoeeccs tale creretens wllorchena s/overmionetcie tienen eke fetee ss 2

OO’ cicieis. 5's. acces ve eek oe ie eile ore) ow ane-akel sraysraneceiere ehene sles 3.0

Gaye tee eiaetorcpereearecsrsbocinite ie orersvenoerte retort ee ctor al

OC ere esa ciara ee als Goteue tens We He pee ane: Siisuale ish yee vatere lie el susie 4

Gay) Hearne HRA otek avons to otons athe Lele tioaloretereraearstel 4

ORCL A Sai oe elves Sees ore een aie NO siolate moe eare lie rsleate 4

Qa Ge aia lays tarcicst oer acl oiateteterai ss ies re tele ores a fove teers : 0.5

OTe reve rairccnbostare saiolicte dors lo, clei ose tevokaensh el ove, wile ct hagetehanevele site fe 1 il

Gaye asc cctussa a cio tivousieucichensy overs ouave Tekeke mieuer sue tetoueveleue, ose 2

CCE e canetests Gieiins Aer oye wnsh ote ies; eee sretensreusuars Gnsvs eyene siete se 10

DVS iajars aps avcre asco let oper ores ates cakes] custodian el ere Geiss 1

ONG es scat ayaiays arava tore Mceyoielonst sastenerooretereierettaeie Ge orabavere ors 2.0

CLAY pe eraie Sita oteral tie atetrelietevelace uel amet eleienere Tooter sexes 0.5

(Oey AIO OM LCOS RCUEAMEICRERG: Chan ice OG COFOI CREO TGR OR 0.5

Clay Ss BO Getiei Meeleole Sele oisioras ernie Gielen eats eeleles 1

(ON cee IE. CS OORT CI CROC MEIC RRC COLOR FCIO. GO OR ee 2

Ay ate are vie oye ans ictoreilspevolsyet oreveclovevercueme rol verietemeaieeWereteus 0.5

ORS SINE (SLANE yor. hievere eal chelots levetonctione oho evacenehsleteboke 2

(ONT GercaIee Ca IneIO OOOO Cc apBa namo tiacoocoO oes Z

Ore sine ram ede eyepeieve sterols overonorersl sleleieserserentelecoreve 1 4

SUE OMS IatS RIE CO TORIES DOE ORG Cea Ors cin: ero Icio Ceioa: ace 0.5

Ones ofine PoraIN EA iene. earths eels) eionstlatelscletcnsterenche 5

GT Biv aieerera cic cisisis seas se eheveteetotelavchernteneler she cyotehcienereres> i

(Oney wins Camiiivenlos pa sno ome odgapcoedeuGRGUDOUUoUS a

IGT GBOtho oi to ator aCIGlOnS IIOICTa CIGD IE ORrcre nic cinta locate 1

GEO MTIME TET AIN EO: fishers roveycrere + elavore<s reiore conereversieioreists 4

Seite abercye tac tettuctscs vevewes stcterapo.cotmvancucte,corousmepshcicvouscereusers 2

OTE mISAN CG eeyetac: rosie Norsters eve a clerneolorer cle rsvonereterelevens ave a

See ceria re torecuctonstte a (evans rays 5 obovate, oy aus ov eieyelterer he sievetelererele if

MTOM SAM Gy seravereh cree sos ts caltche, wife ssVrar aan’ oireitelterehecaratiorairera reels oe 74

SATS) a pycBhek OROuS CREEL ROG -CRCRORSE CROCE EMER HEPOIETE ME PET CIATG Ny CHOICE il 46

ON EOMISAMG epee etetereehetsielsiele) clejeislase wife ehetalelietsie! «chste ac 6

BR cha Go BO cl0O0 COUtrt a OC DIRE Goat o SOO oO oc 1

(COWRA, Gis ooadeaded5o090n GaDdgOOonKDODOUDdOOS 7

Slatemarcitictaererscier 5 SICAL ERG GIORNO RNY CECT 1

irs, lke de dooaoassnocdesdadcucoodado0 soeraOOnS 2

later terisiereserskere Ae ASH LOO CLA ATENEO OORT ar 0.5

A 2

HARLH, INTERBEDDED IRON ORE DEPOSITS

Feet

TEL Gy crear crtereteneeis clare ic tsra eileke afeteraile: sreeneravele rarer eues

OLA se erste re © aoe cia Ghee aay anctavas ave lalate debate Sraettian

SAGO Reyer ane ar cols oes cireisilasiciretersnaneperet aie tate @tohs tenets, shale

OPE SAI iy erere, 5 ck Hecate. cover eens eins ceri axahouste era atetoeieietete

Slaterandesandiy “OL vic civereroeinwlareo uelece evareveressi« o's

OTC SATAY ss aiereecais.a si vse lovane polar eseeausceys ais ay ace eueweverar en’

AV ise eo poser eter ato roo -oikas ueptorr Sys sats (oe naireev aye Slisises ouiev-eics corals Menage

“

DSTA Pe rer eeete each ros ce Mer ckete ance eco Akl cists lobar nwanetaiersahovos

OTEK S OOC aer.doreea ate remece acto leta aca s)0) ayeilay 6, ers, Suse hie, ereveleus 10

QOLCS OOO Traps or iatenene he ovsinetaislaile sae gsc aha totem ie wane sie 12

Ww wa ©

Or Wor

141

Cherokee County. Section at Ford New Bank, N. W. 14 of N. W. 4,

Sec. 33, T. 9, R. 9 E., southwest side of Round Mountain (Phillips, 266,

ib Gad) Feet

Shales COVED oare tate tee eleisiere s hiatenshalels Sweceievsiersterete 6

OreTSOLt Up DWeLAWEMEMG icra ore ocsustens, arose shele ors leceue ee

NATL CONC Most wraraledsiteterts, wiel-e ote, shave tay se, Siar’ a apahs svayena tone il

SATO By CLIO WASH case, ae cata eucllcl cb ensustersr sveievondis telet elefeierere i

Ore, reported to be 2 feet in places, lower bench. al

AM CS TOME Care heyauscsrets (ote leivhers isielelslsyele cfeleaaievarovets eveieie

Inches

Dekalb County. S. W. corner 8. E. 4, Sec. 4, T. 10, R. 6 E.:

Feet

Mn Coes eiepel cha cestenstapsyovew date ladetevecs Ausra rata ora-alenenseroke toate

QressSWalyiyale cats sisveie ca ers ashlee) she suave niereitiwlepsvardie tee eels 1

SHS eae oe roicas de ate ev are la sole a uetsrece, olla oiciataucthuelate chal aietd ors 3

ORC ae rates etsy chara hone fav eda: aust euaite io laroies he coc faites anodteveneleve.tauts alt

SiGiGmGoebewosecgeesbeo boss mn aor oDubboaGooe. :

Same a little northeast :

Feet

STAM etre eter crete cae on ctedere rave tess tere averoyereiulsrenate Mavaito re citate ae

Oe EOOUE Saryeiat ts tretete oe lelels Goetbve ssaeusdare cldic wiete she la's ae

SS hel iy eretictey exchakstohavre toleva. sire Reresecare re: oi slleneuehonatas + au@iotegsrene Se 15

OER secre cre aot avencVoilons) Saray (elaine aye) suc sieve Sie cusyeteneyereces

Shaler cece rasiote s.5 sites ean ia ois thei aatoretslionas Sone esol

N. W. corner of Sec. 33, T. 8, R. 4 E. (266, p. 45) :

Feet

OTe sA Ota ais Aatovahettes ce teaie Orasetee eer Sterse eGo me aie a

Shale abouts. rere cisiom eee ere aienere eines 18

OTe a OURG ac. areas tare otrsne ee lercaiiops sonle Ge Sid nerd wi GS ejeei's ho

Sal Giese ter ep apn otaiere sonata isla claete cers “a Jevelle ea 10-12

ONES EN OO Rens 6 Gio CeO OCLC CRO Onan

For other sections adjacent to above, see 266, pp. 44-48,

Inches

142

Etowah County.

Tad) RG He (266, 'p.48)-

ANNALS NEW YORK ACADEMY OF SCIENCES

Feet

Sandstones with some interstratified shales and

LOI rod oie (are 85. o fode) bie Biol ede sons che: eheuanete weirs lode] oftetens ve eens: 225

Shale; ore; in: alternate Streaks): <i... eters ieee &

Sandstone, very hard, called cap rock to ore....

Sette is. Se oer eee eae a re ee eae ER:

(Ole GAO GEICO A nid cos EDO CMD Ob OO OO COC Ooo

SINS Oi. acdc, Biot ered wie whey elon adiete cc nto e oleuekeco ue tre Dee sie: 5 :

LOVRNIAG Sigco GoonlonUGooo oN DOmoG OOM OOOO OND 6 CGmrc

Shales with interstratified sandstone, about..... 100

Ore, good and soft, outcrop about.............. 3

Shales Sanmadstones vaboult. omits ores crercieeiers > 175

Shales, ore, the ore very sandy and in thin seams

TIN SNA Cs jcrone yee reiese hensiere ioiete shevedoye We eyenel siete eveiareexere.te 10

Loam, sandy, red, with loose shales, about...... 80

Loam, ore, the ore sandy and in loose pieces in

NEC SAN Give LOAme a Ollitiere rie levlencuererenoueie lene terol ceneievere 10

Pelham) (Prenton) limestones: cs cicrsicieivieicte cle ele = oie

Broughton Bridge Gap, N. E. 14 of N. E.

/4)

Inches

‘

{

Jefferson County. West Red Mountain. Section in Pit in 8. KE. 4 of

N. W. 14, Sec. 20, T. 15, R. 1 W. (266, p. 52):

Feet

DEDTIS;: SOUS a ousie che sersnsis wis « aheteials Gisuseueieio es Olle :

Ore, Sandy, aMlare ere vans) rer elciete sieves etenerele D

Shale, yellowish, only in places............... 56

OR URI OnG.ccI LGC GDC ROE LOO A .C.cre OTS 6

ShoailessyelllowalShiiivs sreletvorstere ic ciel sii ptolors che hglentese ue

(ORG: Ce rerio ctateha ton eis te ces oa nletlsnelaherecsereteme tes cses 1

Shale, ore, the shale is yellowish and carries

the ore only in places, in streaks........... aie

OGRE rere contre falls stor ere tenehere tors Leet ntelonsnelal shetesers il

Shale spy ellowaShincicuretierstrerencrctorexne vices eceies L214

Ore, Soft ascanlet Coloma ce ieuctelstete oierenetetenonetone al

Ore, shale, in alternate streaks, the ore is

SIO her Game BSG OOo SOMOS os tahstons He eh orate ee 1

@Orewshalen the Orel 1S Softee -icte uokevee svete tee as 7

Section of Big Seam, opposite Oxmoor (266, p. 61) :

Feet

OSH erie ealcus ie tetas luceicve, ste Rildie he fenedel storeheheke Jers verei eve AG 1

SHAVES MED OLESaiacc. ccleteieleloinlate «wheels ates ate teirare toes Trace

OTOH es ere err eerela tc aa Wows rshoha ans (e aistedetaredevers S atts 8

STHILGS Ir raers etnercreretetcde olde ove toranelasdtolerore spaielmerecene sas as

ONS AE eieiios stots vol ehetes cs yaiey syoyerahelsioig savatelteueveve, 6 siece 2

SNS Warreraarcr ea tanetatetelensticls, chen sistevoloy en siervesnetenelel siromelerrs He

Oressne: siacperedealetedste ts a ORO Dore SONOS COO Ge 8

SHAMLe Wc ateerorsheder slays aleuchevene: suas Biever eS ieiiste Slayereie evexee

Inches

Whore -

ior)

tO & bo

EARLE, INTERBEDDED IRON ORE DEPOSITS 143

Feet Inches

STV AIG Be, Petre retrenlel at ciot oars ofr a rebee ot an evie siesta tarioitallor eitelty on a 2

GOTO oy avel = tera eh shal al sh orec a iat sualel ave Shops otseive: « atecerealeratells S3 11

OTT GP acyekerakshatoncr cvercheiat ci suevehatepavat svaverctabelehesctatgneveless 7 ee

AO) TEC yaratrexatte Satted slike! i eiier ol aie) «'ahac aavehall ae) Sieravanal cretelatotetaters 1 3

GEORGIA

In Georgia, the same arrangement of strata prevails as that found in

Alabama. The porous layers of sandstone or limestone are joined top

‘and bottom with impervious layers of slates or shales. In a few cases,

fine-textured sandstone joined the much coarser layers of ore. 'Thirty-

seven sections taken in this state showed without exception similar favor-

able artesian conditions. In nearly all cases, the ore seams consisted of

fossil ore and always much coarser than surrounding layers.

Walker County, Lookout Mountain (216, p. 96), Edmund Evitt’s

property. Lot 220, 12th district: ,

Feet Inches

SIVAN Paya oateratinseperet sane whey Ser aete eek naa eho pita ere teberstels

COC aye star cr ctoretete lonley a ele tae ar ars ates spellinielace biel ape le niatage eles. Ye -

Solna Oday ere verepete rei seetabek aves cleriaputet tuarade Have ronilen aturey aulsueqec eee 4

OIE RSIS ta to CPO ORCL Oe ORE NCHS IORE REE PCN es PS Seta : 10

HOB KEY: 6 Ber stGawatic Oram Toes CIRCE DIOR BOLE Cre ODER COIR Ero

Chattooga County. Lookout Mountain (216, p. 123). W. T. Henry’s

property. Lot 171, 13th district:

Feet Inches

SVQRW G48. o Sets CIC SIE SORE OOO ICICISII Ore ICT Cee Rs

OTLB pe eter oat aie shore tore: overdo oesuaisloneta alerane eis ere locas eeiele 1 2

NO NEMONeytest cera telote a cilehetena love ote) ciate char oiglousiefeleiatere.ecets 1 10

Ore rsa fos ee Bie Siete soka, oecl ehouenetabe mye ew swt oh elie ekeetove 5 4

Sly all Ginn: sddapey teres cher ace ws tad patat ee sie iol ats atelier ete aia See 6

Oregeie. DONOR CICRES DIG EEE OLS COO ICRC eT Rae 2

ST werreteuarecerstsiotere Sates, deine aleustetaarele erelew alelstersieiate

Dirtseller Mountain. Z (216, p. 130). Lot 150, 14th district:

Feet Inches

(CURE Soi DO iC OC GEOG SIOIO Ie i TOROS SIRT an ene Ur mae Hae

(e)

Ler |

OHKRAODEED PA.

(QR Sirol CASS atsnelatateheve la a eicvetss lavecs| eveisteve his

14-4. ANNALS NEW YORK ACADEMY OF SCIENCES

Taylor’s Ridge (216, p. 133) :

Feet Inches

Heavy-bedded ‘Sandstone =. --.iscewicis « etereretoieioieis els

(OL ey ety oro eR ERIC AOR RIS en AGG Occ otadaes ots 5

S01 1 ce er eee Rot etc mets cGeehenS. Gio ics OR CRON se aL

QO cGare wis Biche vsilsice:efo, ashe ovate one corakouehenor onotelive eter ete etey ee al il

OTIC TD 5 lays eve ferede asda ho wrest BSc oteke ckerlone o esenel telotersioie te

Mr. Maddox’s property (216, p. 135). Lot 160:

Feet Inches

SANASEONE vac kove sleeve lolekovere, sheseilens ie loveieroterey oareeeieteenere ce ae acs

OLE saiehein by avetts taker eyaves of te lois ohare teliartarelovereveleteielel efekeiete ler le 56 7.5

SHA CMe er cccioieucis cite toe rovetnic, eteiGue aincle ere Mra creat fe 3

OTC reo teiver cece svonstovaseuete iota) she tone Weiss ete Jonata tetouetete tereraneiehiwetee te i a bts

SAME accrrerctavtaciate eisreuets des fo ete owe iskere ee neraven na eon 7

Dade County. Lookout Creek (216, p. 59). Lot 83, 18th district:

Feet Inches

Ore (overlain Dy Shale) micccciesiete ae ciclo isacio es Sie 10

SAVOY eoies-sepesouckcieveke ates cisyaie sors iolelin eveieleretelsleois: obeForevere ae 8

(DCs one vs Taifareie ie iofoto eG foie feloiey ase coleie ls cave polevereieis eislaseerere 1 ae

SINR Rais otto tehete bee are rern lays fosloue. velo Pavers. Whale elec lord wfoiete 1

ORISA ROR ROS LOND OIG ORT RE CEOS eet rr ee Ste a 6

SIAC Gis thee etocleratelo ae efovelotoelo e Bvsteleos ie ntotowlere tote olor 3

ORC Meo efoecs Biot usters Santis « ike Siewe woth Oho ore iforsiele 6

SAG ercteyratetesspeynlste avers, ote S ove) eaene eho evore ersten ole eneretel shave Be il

OC Fer ucuede retteveh oteuecy cle tsieiei@ lavehevere ioiee ete talloreteter tie erences 1

STAC metare.cteystaetshoha eters bie) Sialtehelais lem retslne cam lepeitor aie 2

Herrurcinous) fOSSil Limestone. /reis cl eters ole) ole als ae 9

SH al Oop gee rarctayeee re ates fe ret bieiel old atekors ers tekoetslepeltenstetenerts 6.5

HOSSTIFELOUSs LIMESTONE S scr uss-atereteceuehelotener susie strche ous 4

Shale with thin layers of sandstone and lime-

SCOM OM ere caerelavs ous ieis, PA ayeveso elaiis ol eipiecetetenevensielers, Suelo 40

TENNESSEE

Safford (295, p. 304):

Feet Inches

Greenish shale........... Weis rele ie bretedeuetone. doavetereceevels 22 %

Orevwithsparcine Of Shales..-v. cco ctciirele cleleroiseeleTe i 6

SANASTONE aN CuSl aimed syste cicie loveietebeiche Sleketoteleleleiete 6

Greenish shale with occasional iron seams...... 67

OolitiChorew calcareous jose vee s celcls we Se nictetelelos 4 a

GPECNISHESH RLS che ort sis wcois ct bie c she eer Miolore eieorei Rare loiots 21 3

VIRGINIA

Low Moor, Horse Mountain (92, p. 188) :

Feet Inches

Slates andsthinisaAndSstome vee cls isle icles vic sls, « ie 3 10

Fossil ore, brown and porous.............. 5 7

Hossilsorenredsand tainly; SOOM sec. ete ieee eel = 1 2

CHER Ye Cl ayacde rere sercistoreitoteleiens isos sic leveushe siete) Crelisyeileyoxs 6

RSH ET VEST ang ye earataass Ans RCE AEE CRC OREN Cin, Oc RRO ICA ACER Dy

EARLE, INTERBEDDED IRON ORE DEPOSITS 145

Slope 2:

Feet Inches

WOH CUWENNWANIEG BK5ooobOobbUGODODnDOOCOUuDOUOCS 30 a

SMITE Sieyeeereeraia cress related cdenah axed af earteychcbercne) ester ehohehotehshe lis pe

FRCAGROSSTINOLGretsr einer eves sch) doyevchoneiel clalciietorsacrelsioneieie 1 4

Ochery shales and thin sandstone....,......... il

ShalestanGesamadStOnme acces ctelslersvele ovetetatstoneloictelehs 2,

Big Stone Gap, Va.: = ae ee

Slate spac yanvea tiered sac cis cterelerclelelcierclereiels <i olenele il

@MOlICRORE Te Poet rcrere oreo s rs oa oheelatadarero are eave siclo-e A 8

WEST VIRGINIA

In West Virginia, the same artesian arrangement of strata prevails as

that found in the more southern states. Shales overlying and underlying

ore seams in almost all cases.

Pendleton County. Wagner Knob (130, p. 166) :

Inches

an anemwalleoreeneshale ncyercierelercloisisieielsielcreielelckelelelsl«/ lee

(CC OOGR GOLEM ea erate oto ciate kere e la tonelies OR te tevoret olobane tone crete exeveteress) eile 5

IDI STO OENye cae paeooeo du OOULUoMC GOH OOOOO DODO OUROOCG 4

Site hic: Cine soc SG GtOO GDC COCO. 6 HD OOOO nC UUDRICOMOUUUOC 18

INCOR A Guligeds Go Bhbes GORDO oer on.o GOO con one corimo ere oor

Hootnwall sereentshiall Gaererraiciccrerersierroicte crore toeholiet=lelenoe eis

Z (1380, p. 167): ae

Ean einewallvoreenesnal@yyeraci-istetererso ciciciicter-tsieisisissersis ae

GOO Oe ae erereieicne lore heteloae aia cdi ay eva otete) oforey.s leks: eye she hal svete: st 6.5-9

GTECMESN ATES: ee so aleiels sie oy ete austere ei elstione, Sher ers. iepei svevett aa sre. (Cow

COOUTOLO Rares ates o. suavelisceravereceislsiave oisle-el'steretege etenenereiae ties 3-4

LAE Y BOLE rae tata cere teks ele iy otatenede enslolenesrepate ctlnvcie, etsy orereus) sieyets 4

GrEEMY SIDES iocisy te Wis ohsadrevotevakar thaletelets ie) cyaleneuole scetsyenaleetestte 9

SlatyeandeSam diya Ore crerersi-tata clei) sieleleici ciate dice cleisis eictoler cers 5-6

Hootawallworeent Shale ct. 1c erie sc aleretelsnstovsielcheroleiols el avele ere

(130, DP: 197) : Feet Inches

Black shales....... AS SOU nD DCO OEOC COORD RECOODS 4

VEdE TOSSUEMEIMA TCO sayencreretevs rol cieteteiersie? hotoie avetelersteve al ae

Thins fakeys WblacksisShale.ys scm cmerecteielctelsiciels savetsisie we ft

MAINES COMO acc sc.0 ea ce siete ereicre: oleteliseoverareveie.e eve, cueletsis st 2

Shalesiwathy limed ayers. cercrcicis cree otic e.cisiets ciel: 1

PENNSYLVANIA

The same arrangement of ore and shale is found very generally in

‘Pennsylvania.

146 ANNALS NEW YORK ACADEMY OF SCIENCES

Union and Snyder-Counties (84, pp. 65-68) :

Feet Inches

Sandy calcareous shales.............-. q5307 175

Oy (Vol eri anganoonacagaadaddgacododds 2-3

Purplish red! calcareous Shalerty. .iteieiel-le ie 10-380 oie

Ore; Danville sores. cc evcssys sie else ele eles eleteteveyeners sis 16-18

Shale smiddie olive Shaler ci... 1-1-1 <heleseveleteletelase 150

Iron sandstone and shales......... rate gists opsks 60-70

Shale; lower olive shalet <<... 1+ sisiclele eqs leiels 500-600 AN

Birdseye OSSil Orelyeveie «cles sievelel leis eleveyetere aC 8-10

Shales; lower Olive Shaless 2.0.1. + icreleseieieie a’ 150

Moores Ore Bank (83, p. 58 F):

Shale White clay, carbonaceous

Ore Limestone, at top a rotten olive shale

Fire-clay Sandstone

Ore

Granville Gap (83, p. 46 F): ae Dek

Hower Chinton; Shales seyeiieicrerreleielclelekepsietele/erets 135

ISTOCK-OLE Ge tickeicheiele cievsiees oreeiaielo aerehe isialorenehole 3

MELrULINOUSBSATIC STONE! is eucleneietes cieleleleleneeyer 6

Shale, light green and yellow............... 30 fe

BITGSeye OSSIIVOLGs 1G. cele laieve eieleleierele la lei- ats 8-12

VElLOWaShale treet lleiercrecrsoeirelersy ores eieiehererereiene 30

ELOCK-SHOG- OCH icteloteleleisionsie) shoketerel sfolenoteloislevelerers Ae

IES ace ccmonevorereast ovecenevagewevensse ake e¥eiscswerors coke toans 150-200

Medina sandstone; sNOnLVislejict-ieieieswelsleisie olels1<

NEW YORK

The Clinton red hematites of New York meet the requirements of the

artesian theory: impervious layers of shales and cherty limestones, with

coarse Oolitic or fossil ore in the porous layers.

Genesee Gorge, Rochester (234, p. 20):

Feet Inches

Bluishseray limestonens-iciec- 26 ee SaaS ODES eee AS si

Greenmsnaless. ta iercersieke ci oioietarare a Favepeite (oiets\e oh orexet 24

Hard siliceous limestone....... FOO AA OOIG Nonie oe. ie

WEONGOnELOSSIl ay eee eee eine a he oie tote Sate efelia ous iid 14-16

GreeCTESH Alerter icke res icus nre wie lsielaialehensustere dial ete lavexee . 24 ae

Ontario (234, p. 21):

Feet Inches

Cherty limestone........ aye leuarene sis erate latsiene-siele tetevets 8 a

TRON OLE: MOSUL ore a leseke eters ars. siete clsle eterclstetsie voteustele 2 2

Green sshalersercciei seis ticscle mr obonetettcenetererenate siateuare 9

Medina shale........... miata a yavela lo teva aleve el eicons) we tore loko mummers a

EARLE, INTERBEDDED IRON ORE DEPOSITS 147

Clinton (317 and 216, p. 29):

Feet Inches

Sandstone, calcareous, thin shale at bottom..... 50 ae

Red this bedyshalepartings. oc. .ccc. 3 clcie ese cls 6

Sandstone, very calcareous, with small seams of

1UN0) Th AG OC POR RIC IIOIE CLO. ODI o DOG 6

STAG pcre eka tate Ste sacirelvel score levoiay Me te setei-cl el tracevenefiarsver eves 15 ake

ONCE ONC ereiere.c.c1s, 0202 oe ereiei sselekeverexeys cvcteroreveraierersveis ae 25-40

Shales merely, asp aretin Os «\<1syeleia cre) cievsis etelelerel sisi sl «tele 2 56

@OMAGCLOTC goin. wis cosy soletd sila e aide ie alee cis Slave crouse ohare

Shale witha somensamdsGomey-i cee) cies clemiciencic crore 100

NGVA SCOTIA

The same artesian strata are found in Nova Scotia. It is uncertain

that these ores are Clinton, but they are called Clinton by several writers,

and until they are more accurately placed, they will be referred to as

Clinton ores.

Baker No. 1, Pit 10 (South Side) (356, p. 71):

Feet Inches

OTR OR IG Net aaa cote e oa tahahes alates aim os Tata Sreveieie @ Se letelele aioe Ss 10

SVE reenter are solani e: wictenaza) oferel ox ehoieg, Stoupvera Wiel snsverehecene 2 10

ONC tacos eae oy eyaieN ciie) aohe del ovssdaior anal ahel orev ai ageKe, GeolecereNs are7ays +

SS eatie ieeitees ay ated oh cttarre, nate ete ytacue Sus, ous hev’o, a Sue lapedeveuaye/eiste tere 2 6

TO arape it ena hoot aha fe PS ielepel elle sd te lah a oilslis face Duane Mie levelalerer es 0

LAE Cie teres areas ene cee afatc cycle: bichayaleveceveretelon le sLeeiene al 6

(QinG), Sarin ERAGE eee OIC tetonc cline cic CicnerO D, 3

SCM Aree ah acer rar ete bial Miche lous slike Gheid oherebelohot es telel ots 3 3

OTe re eres orcas ies hel crete alec 1 hauske er ape love tetens wlolotonsbere tess, guste 6

Leekie Vein, Pit No. 24. (356, p. 80):

Feet Inches

GEreEneSobtes lA Tees a te rstere «wy ouet acoavores © oils teteeteiere aye tere 1

TOR earcie aie oler ethene ai s-doal Seay atadeedl Gee leveteeeia/e aieinieeveleles il

SLAC yor atepres cteretas suo etate ie stse yee anes etre abe taitetalleh dys 1 3

OB steer ats hails Hoke unis Le Meee POT a A eases ereiect 6

ARTESIAN CONDITIONS IN THE CLINTON DEPOSITS

A close examination of a hundred or more ore seams, distributed from

Birmingham, Alabama, to Rochester, New York, has been made by the

writer, and in practically every case structures were found that would

favor excellent artesian conditions. Beside the seams personally exam-

ined, practically all available literature that contained sections of Clinton

deposits (and including some unpublished manuscripts also containing

sections) has been carefully examined, with the same result in nearly

every case. Out of more than eighty sections in Alabama alone, seventy-

148 ANNALS NEW YORK ACADEMY OF SCIENCES

two showed ore seams with shale or clay partings or strata ranging from

a fraction of an inch to several hundred feet in thickness above and

below.

Taking up the artesian conditions found in the Clinton iron ore de-

posits more in detail, we find governing factors.

POROUS LAYERS

The first are the porous strata, or better those which were without

doubt originally porous, and which consist of fragmentary rocks such as

sandstones now in many cases altered to the odlitic hematite beds. Seams

of this class were personally examined at Clinton, New York, and Big

Stone Gap, Virginia. Specimens of odlitic ore with quartz grains as

nuclei were also examined from Kentucky and from Wisconsin. Records

of similar strata have been found in Ohio and West Virginia.

Rock slides made from this class of ore show conclusively that the

original sediments must have been ordinary shore or near-shore deposits

of sand, similar in every way to ordinary marine sand such as we find on

our beaches to-day. Sand, loose or consolidated by cementation into

common sandstone, forms as perfect a porous medium as could be de-

sired for artesian purposes. Some sandstones show as high as 30 per cent

pore space. The other principal type of Clinton ore, the fossil ore, con-

sists of beds of fossil fragments such as pieces of crinoid stems, corals,

bryozoans, brachiopods, and many other varieties of Clinton fossils,

deposited by the ordinary processes of sedimentation and later consoli-

dated into the usual types of fossiliferous limestones. These furnish,

in the earlier stages at least, ideal porous conditions and are quoted by

practically all writers on artesian flows as favorable for water penetra-

tion.

After a close examination of slides of these fossil beds (Plates IX,

XVI), it cannot be doubted that for a time at least these layers must

have been extremely free runways for penetrating surface waters. Arte-

sian reservoirs exist in rocks like the coarsely crystalline limestones, far

less favorable than either sandstone or fossiliferous limestone, and there-

fore it would appear to the writer that the complete porosity of these

layers can hardly be disputed.

IMPERVIOUS LAYERS

Impervious contacts were found, separating two strata of different

textures and degrees of porosity.

As has already been pointed out (page 138), where two porous layers

EARLE, INTERBEDDED IRON ORE DEPOSITS 149

of different density occur together, there seems to be a natural tendency

for either mechanical or chemical filling to take place, beginning along

the line of contact and extending a short distance into the finer-textured

stratum, thus protecting the latter from further penetration by the solu-

tions contained in the coarser layer as effectually as though the finer layer

had been impervious in the first place. This is well shown in various

specimens of cavernous consolidation (Plate XI), in which iron solutions

penetrated the finer sand for a short distance, filling the pore spaces so

completely that part of the inclosed sand remained not only uncoated

with iron, but even unconsolidated.

MARINE ARTESIAN SLOPES

Marine artesian slopes are among the common sources of artesian water

supply to-day. Strata of alternating sand and mud, often many times

repeated, are among the commonest types of in-shore deposits, and these

sedimentary layers as originally deposited have an initial dip. Further-

“more, the coarser and more porous layers as they extend into deeper

waters tend to change their textures from coarse to fine and their contents

eventually from sand to mud or ooze. These conditions result in a nat-

ural catch basin for penetrating water that cannot be improved upon for

the establishment of good artesian conditions.

The Clinton beds comprised alternating impervious and porous layers,

forming the marine slopes of the epicontinental shelf of that period, a

condition in all respects favorable for the retention of artesian waters

after uplift. These runways probably were brought to an end downward

by a change of texture and material from porous to impervious deposits

seaward ; but even if such a sealing of the porous medium did not occur,

it is highly probable that in a comparatively short time precipitation

would cause a filling of the voids at the lower end of the runways and

accomplish the same results as a change of texture.

INFILTRATION OF METEORIC WATER

That conditions favorable to the easy penetration and retention of

ground or surface waters could exist, therefore, seems clear; and that

penetration of such water in these channels took place is equally well

indicated by field study and the microscopic examination of slides from

Clinton seams. This is shown by the evident and widespread corrosion

of the nuclei of calcite (Plates IX, XVI), and even quartz in some cases

(Plates XX, XXT), that form so large a part of these deposits. If we

150 ANNALS NEW YORK ACADEMY OF SCIENCES

admit that these fragments and grains are corroded, we must also admit

that solvent waters were present at some time in these artesian runways.

We are not dependent, however, upon this one bit of evidence. The

penetration of iron for short distances into slightly porous contact layers,

with a progressive thinning out of the iron (Plate XX, fig. 2), until

within a short distance from the line of contact penetration and precipi-

tation altogether ceased ; the filling of the seams caused by cross-bedding,

muderacks (Plate X VIII), sand streaks in the shale, fractures and places

of weakness, all point to precipitation from penetrating solutions. Cav-

ernous consolidation in loose sand layers (Plates XI, XII, XIII), filling

of corrosion embayments in nuclei (Plates XVI, XX, X XI), widespread

replacement in all stages of completeness of calcite and in some cases of

quartz by iron, and the secondary calcite, iron and to some extent silica

cementation of the iron-coated fragments, all add to the certainty of the

filling of these retaining layers or catch basins with artesian waters.

Thus we must conclude that all the factors necessary for complete

artesian conditions existed in the Clinton strata; that much evidence has

been adduced that these natural artesian runways were well filled with

ferruginous solutions, and finally that these solutions were responsible

for the present mineral content of the ore seams.

OrE CONDITIONS RESULTING FROM ARTESIAN SLOPES

DEPTH OF DEPOSITS

The only downward limit under this theory would be the limit of the

artesian flow. As artesian wells have been sunk in some cases to more

than 4,000 feet, and as artesian conditions would seem to be as perfect in

the Clinton strata as could be expected anywhere, it appears to the writer

at least that the only limit of ore deposition would be the seaward ex-

tremity of the porous strata, and that this limit might well be expected

in many places to extend to at least as great depths as any artesian well

known at the present time.

That borings in Birmingham, Alabama, have demonstrated the exist-

ence of good ore at 1,902 feet would appear to bear out the writer’s con-

tention that the iron content of the seams should extend to great depths

with little or no change in richness within the hard-ore limits and that

this condition would be found wherever the proper artesian factors along

the marine slopes existed. In Holt County, Missouri, a borehole 1,885

feet showed good ore at that depth and favorable artesian conditions be-

cause of the impervious overlying and underlying beds (66, p. 148).

EARLE, INTERBEDDED IRON ORE DEPOSITS 151

EXTENT OF DEPOSITS DOWN THE DIP

Some artesian flows are found to extend for more than a hundred miles

from the outcrop, and flows tapped scores of miles from the intake are

not uncommon. If we admit that artesian conditions are responsible for

the existence of these ore deposits, then we must recognize that the limit

of artesian layers alone will determine the distance along the dip to

which these deposits can be expected to extend. As one fairly good ex-

ample, the case noted by Newland (234, p. 51) might be cited:

“The recent exploration with the diamond drill has shown that there is no

notable change of character on the dip for distances of five or six miles from

the outcrop. Deep borings made some years since at Syracuse and Chittenango

found hematite below 600 feet, showing it to be of normal composition.”

WIDE DISTRIBUTION OF DEPOSITS

Conditions that caused the formation of artesian runways, and later con-

ditions that brought about periods of heavy rainfall and rapid weathering

sufficient to produce the iron-bearing solutions that penetrated and filled

with iron ore these artesian runways or reservoirs, were so widespread

and extensive that no merely local results could follow, but rather the

development of a series of artesian slopes such as we find along the whole

Silurian shoreline, well filled with ferruginous material.

OCCURRENCE OF OOLITIC AND FOSSIL ORES

Whether the porous layers were limestone or sandstone would not affect

the question of genesis in any way, under this theory. Sandstone strata

might produce odlitic hematite, while fossiliferous limestone might pro-

duce the characteristic fossil ore, and still both types were dependent

upon similar artesian runways and penetrating iron-bearing solutions.

VARIATIONS IN CHEMICAL COMPOSITION

As these Clinton ores extend nearly two thousand miles along the out-

crops, and as the old land areas varied in composition, in some places

containing acid rocks and in others basic with different mineral con-

stituents, a difference in chemical composition of the ores might be ex-

pected. The fact, also, that the porous layers differed to some extent,

some possibly having a primary silica cement, others a calcareous cement,

and still others having no cement whatever, these and other minor varia-

tions in the original deposits would lead one to expect just such variations

in composition as we find in ore beds to-day. It would, therefore, still

152 ANNALS NEW YORK ACADEMY OF SCIENCES

further tend to strengthen the artesian theory that such variations in

mineral content exist.

VARIATIONS IN TEXTURE

Variations in texture would be inevitable, exactly as they occur to-day

in any series of marine shore deposits, and the texture of the different

ore seams varies as would be expected, seams of fine ore and seams of

coarse in the same localities being found, and also variations within the

same seams.

VARIATIONS IN RICHNESS

Artesian conditions would also account to a large extent for the varia-

tions in richness of the Clinton ores of different localities and for varia-

tions within the same seam. Differences in temperature, pressure, rate

of flow and size, shape and composition of the grains of sand within the

porous layers would all influence the degree of richness of the ore, as

would variations in the nature of the cement.

Artesian replacement, therefore, would account satisfactorily for depth,

extent along the dip and wide distribution of the ore deposits. It would

apply equally well to the fossil ores or to the odlitic hematites, and it

would satisfactorily explain the variations in composition, texture and

richness. ;

On the other hand, the absence of artesian conditions would account

for a deficiency or total absence of iron in limestone or sandstone strata

otherwise favorably located. In Niagara Gorge, where the Clinton strata

are well exposed, no ore seams outcrop. Otherwise, unaccountable breaks

in the continuity of the ore deposits could easily be explained by a failure

of the strata to provide good artesian runways or catch basins for the

iron-bearing solutions.

ARTESIAN REPLACEMENT THEORY AS APPLIED TO OTHER Horizons

It is not likely that conditions favorable for the accumulation of iron

ore in the porous strata of artesian runways will be found in any other

geological horizon on such an extensive scale as those of the Clinton.

The peculiarly favorable conditions resulting from the rapidly changing

textures of sedimentary beds deposited in the Silurian Sea, and the periods

of crustal movements, heavy precipitation and rapid weathering which

followed, furnished a most remarkable combination of factors requisite

for the formation of great numbers of artesian runways, with ample op-

portunity for subsequent filling. It is to be expected, however, that

artesian conditions will be found in many horizons of marine strata at

EARLE, INTERBEDDED IRON ORE DEPOSITS 153

widely different ages. If these artesian runways have been so situated

that mineral-bearing solutions could penetrate their porous layers, there

is no reason why deposits similar to those of the Clinton age should not

be formed.

The exact stratigraphic position of several of the so-called Clinton

beds is uncertain, and when the fossil content of these beds has been

worked out, some changes may be expected in their stratigraphic posi-

tion. The geologic position of some of the interbedded hematites and

magnetites of Nova Scotia, which by some have been classed as Clinton,

is still in doubt.

The writer has used the term Clinton more to characterize a type of

deposit than the ore from a definite geologic horizon, and it is probable

that several beds referred to as of Clinton are not of Clinton age. It is

certain, however, that all the occurrences treated in this paper are well

within the Paleozoic.

DEPOSITS OF WABANA, BELLE ISLE, NEWFOUNDLAND

The Wabana deposits of Newfoundland would appear to meet the

requirements of the artesian theory fully as well as the beds already

referred to under the Clinton. The porous layers now represented by

the ore beds, the impervious or less porous adjoining layers giving good

artesian runways, the marine slope giving the proper inclination to the

beds and the necessary limit of the porous layers by marine slope methods,

and finally the great depth and continued richness of the deposits, all

point toward artesian replacement.

DEPOSITS OF THE MIRA VALLEY, CAPE BRETON, N. S.

The Cambrian ores of the Mira Valley, Cape Breton, also have the

necessary factors of artesian ore deposits. The iron ores occur in lime-

stones and quartzites as the porous layers with slates interstratified, thus

giving the same general conditions as were noted in the usual type of

Clinton deposit.

Study of other deposits indicates that although this theory is more ex-

tensively applicable to the Clinton ores, it is equally applicable to similar

beds of iron ore in other horizons and may be found useful in working

out the origin not only of other iron ores but other minerals as well.

GENERAL SUMMARY AND CONCLUSIONS

The advocates of the sedimentary theory, although advancing many

plausible arguments in favor of their ideas of origin of the Clinton ores,

154 ANNALS NEW YORK ACADEMY OF SCIENCES

yet depend upon a condition of ore deposition unknown at any other

time, the direct precipitation of iron ores in sea-water. Posepny says

(273, p. 121)

“In short, a number of investigators have adopted the hypothesis of an

original deposition from the ocean without giving any other reason than the

observed relations of stratification. Yet, in a considerable experience with

ore-deposits in marine limestones, I have never been able to find genuine ore-

beds among them, but always only ores of subsequent introduction; so that I

feel warranted in believing that such beds proper do not evist.”

They recognize many factors that are difficult to explain under their

hypothesis. Many conditions are found that cannot be accounted for

under this theory. Moreover, the principal points in favor of the sedi-

mentary theory apply equally well to the Artesian Replacement Theory.

The field conditions, hard to account for under the sedimentary hy-

pothesis, are expectable under the latter theory. Instead of relying upon

conditions unknown before or since, the writer bases his deductions only

upon well recognized conditions that are known to have been in operation

during many geological periods.

The writer has therefore come to the following conclusions in regard

to the origin of most of the Paleozoic interbedded iron-ore deposits :

1) The Clinton strata were favorable for the deep penetration of sur-

face water along well defined runways of porous rock, protected top and

bottom by impervious strata.

2) Iron-bearing solutions actually did penetrate these artesian slopes

and were to a large extent responsible for the deposition of the Clinton

hematites and other interbedded iron-ore deposits.

3) The strata were evidently marine but chiefly of a near-shore type,

as shown by shallow-water conditions such as the accumulation of large

deposits of fossil fragments, evidently broken to pieces by the action of

shore waves and ocean currents.

4) Corals were found in sufficient number to indicate that conditions

necessary for successful growth of the polyp, such as mild climate, shallow

water, open sea and a lack of much fresh water, must have existed.

As the beds were marine, shore or near shore deposits, they must have

been formed with a gentle seaward dip.

The Silurian Sea produced all of the conditions necessary for artesian

slopes.

After these strata were formed, elevation took place, so that the out-

crops were above the sea and the porous layers were then in a position to

receive surface water. Then came a period, or possibly several periods,

of considerable precipitation and abundant weathering; large volumes of

EARLE, INTERBEDDED IRON ORE DEPOSITS 155

iron-bearing waters, deriving the necessary solutions from the old grani-

toid and schistose rocks, found their way down these natural runways.

The water probably contained considerable carbon dioxide (CO,) and

thus, because of its own nature, aided by increasing pressures and tem-

peratures, became an active solvent, until it reached the saturation point ;

it then became a depositional agent and began to deposit. The iron salts

were probably the first ingredients to be given up; then followed other

constituents, such as secondary calcite and silica which form a prominent

part of the final deposits.

The solid particles which were not entirely dissolved from the original

constituents of the porous layers, and which included in many cases large

numbers of quartz grains, became centers for the segregation of iron.

These quartz grains were therefore first corroded to a varying extent and

then protected from further corrosion by layers of iron and in some cases

secondary silica. Finally, the remaining pore space was filled in by sec-

ondary calcite, sometimes mixed with iron. In a large number of cases,

the iron replaced both calcite and quartz. This is well shown where the

iron has worked its way into microscopic cracks and gradually clouded

the quartz and other nuclei and in many cases actually replaced it.

The artesian contacts are fairly clean, as would be expected, the shales

and clays furnishing the cleanest of the contacts except those forming

along fractures. Where such breaks occur in the inclosing layers, they

are filled with streaks of iron ore. The iron appears to follow fractures

and other such planes of weakness as lamination or stratification planes.

Tron also fills mud cracks and other holes and porous places left in the

shales and other contact layers.

Where iron has penetrated a short distance into the inclosing layers, it

appears as though much pressure had been exerted upon the solutions.

Depth, extent along the dip, wide distribution, differences in composi-

tion, texture and richness, all can be accounted for under this theory

without the necessity of appealing to special conditions, unique for this

particular period. Under the artesian theory, deposits were probably

made with the usual deliberateness characteristic of natural processes of

deposition. It is entirely posssible that the time consumed in the com-

plete filling of these artesian runways with ore was many times longer

than.the time taken for the deposition of the sediments that composed

the original Clinton layers.

Finally, under the Artesian Replacement Theory, the genesis of the

iron ores shows an interesting similarity in many ways to that of origin

of the Lake Superior hematites and magnetites.

13.

15.

ANNALS NEW YORK ACADEMY OF SCIENCES

PART III. BIBLIOGRAPHY

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160 ANNALS NEW YORK ACADEMY OF SCIENCES

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162 ANNALS NEW YORK ACADEMY OF SCIENCES

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148 : Kingston Folio, Tennessee. Geol. Atlas of U. 8., U. S. Geol. Surv.

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150. : Sewanee Folio, Tennessee. Geol. Atlas of U. S., U. S. Geol. Surv.

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: Idem, Pt. I, The Tennessee Valley Region, pp. 58-59, 375. 1896.

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ANNALS NEW YORK ACADEMY OF SCIENCES

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294

EARLE, INTERBEDDED IRON ORE DEPOSITS 167

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ANNALS NEW YORK ACADEMY OF SCIENCES

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ANNALS NEW YORK ACADEMY OF SCIENCES

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Part i, No. 20. 1909.

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Sci., Vol. XXXIV, pp. 113-127. 1912.

ANNALS N. Y. ACAD. SCI. VOLUME XXIV, PLATE VII

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Vol. XXIV, pp. 171-318

Hditor, EpMuND OTIs Hovey

CLIMATE AND EVOLUTION

W. D. MatTtHEW

NEW YORK

PUBLISHED BY THE ACADEMY

18 Fepruary, 1915

THE NEW YORK ACADEMY OF SCIENCES

(Lyozum or Naturat History, 1817-1876)

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‘i 1 ANNALS N. Y. Acap. Sci., Vol. XXIV, pp. 171-318. 18 February, 1915]

CLIMATE AND EVOLUTION!

By W. D. MatTtTHEW

(Presented in abstract before the Academy, 13 February, 1911)

CONTENTS

Page

DTU CLS EMM ETI e Gaye boats 2 ace dates Me nerap etal Stepetea nm del Sials ete wieweite ce 18@) Ore Poe oak cree 172

IFAT eT CRC tal Oneness cto, te otireceroiel avon aller ech eter cred etetotanteyeireltal anal et ele (oraseliohaie @erene si elerer 173

Alternations of elevation and climate during geological time....... a6 Alri

Rewmine paseo sien GIECRIN RSIS a aqdae eo bododa soo Ob coo tNaoomadcdc 174

Distribution of land and water, present and past..................- 175

Effects of alternations of elevation and climate upon evolution of

COLES EMEA le PAM el Srerere siete oe oiiete- BRE SRO OE OO HO AEIOD pic dino Oc 176

Comparison with the paleontological record........ SA LS chee 178

Interpretation of supposed exceptions................+-00:ss-0--0-- 179

PTINGI PLES sof MISPELSA lla, as sve hevs ie siete sas ceeypoepateyeiewsvnds a)e,8 ERS OM OER otose 180

Review of the evolution of vertebrate life............-....0.-02.0.. 181

Imperfection of the geological record.............-.....++-<s--; Siete terevets 183

Zovlogical regions, past and present.............0.-00.2-eeee-e Stak eeere crete é . 185

HOLME APICES mam CoD SS tay fer euelaerelctsrelcrelenel eictieronencneied oekelietel cre lelete! «i-tele)iait> 189

VeGSTONA CORTE) ALOMrgers vets aieienavaie eleletetsiel cle sellecefeoroi ERE RR RCSA ol CR eear a ts 191

Synchronism and homotaxis........... Sedes sate SPRUE, owt stat oaewetepare Sauaks ts 192

; TAATAAy CORRARIHOIN Tol Souiln wlNeinKNes oa oobnoe donc s00o 005 Soo ou sO oS 195

GCENCLELSHOsGISPERSAlevere serie ete oles |= la ere raters eve 1s (ots tele eheliotelatevoles sie WO Sraictalehee 200

Oceanicrandaconrinentaluis!andSryen cael seicios cteis o averei ole eyelet ale) eller aie\elote el ereres 202

Faunal differences between oceanic and continental islands.......... 202

Natural rafts and the probabilities of over-sea migration thereby.... 206

Considerations affecting probabilities of over-sea migration in special

GASES? ciajsie shaves ons Seaensreues ER hapa ath chenevitie evs tata a ataits vance eyicr otepe aisle swale ateponse SOS

ID ISGELSANO te eiey TT AN Aeterna alee eels) elena) feline aterchalaiielajaite).cl stele Bt spelehs ey-vste 209

WB Vis 5 ey ose See NAMM a tic satens raratarey er cheverateiaNenet cliellsiehs essreste leyoue: afousel's Paiste Sas 209

ESPIMAATCS yey cletateiiekechetheleveune ee Bot kekebadeenats revels eC Nraratist sie COVA a aMebeuallaras @isy shane eit 214

(GRIT SHON ERI. ORs een Ales tier 6 EIR RICE CHOY ONC RERORCR) ERE ca ee nCROT on te PRE cc Beek Ped clten! Ors 217

COE INIG Baineena teecicmen ett Nee eS BOA tena atte toe ai cealetes PPR yah LAS RON ed PR eae Pa 218

TO CY OMe efeueyelere sie avy eles eels coe ele Arete eM beleyaie witthensintetese elected 220

IVIISEGIT CEE taeveleerciatsvereter siciere tetetslene ee lers AB AUR etereteralstavernie wileletako crenata ows 221

UOTEEHOR DAIS OSE OF Gis Widid ides Se Gore td DIOP RCo Ce Ie eee ECRECICIcrO taro ac 221

WEI GT ET ASO tea yereievetara sues ce! aleurone eles haere nehereiets elatadhine withoeh atoints asics 222

15 Wiss) Pa ae Gio eels Ns Te eaCTCIAENG adecal etches cial ot cuntlavehancus ie isdel exe (6: 8s, 66F sus)» 223

TOYS Ee Snes eel HAR eee. cI ONEe CRI CHG REMI Aahaicusvsvarsts ESP APNA eat eae ererere sae 223

TPMT AYER Gp aad PROCS Oi he ov PONS CG TS CS RAC NCTE THERE ARNON EE MICRO IGN SNE RCV he 27-34

PMSECULVOLE 2) 6:2 a: eheiei ais ane PieToreisl shetevars saceieie isis einiele\ere! sre Fe SS OP ALONG Oe 224

Chiroptera....... Se OORT, COTO Ie shevlaba tabs ye ate: re deve ata a9 el eae eee 227

LOGO Sg o SES ee dics Ors ORE TG ERC CRO Cie ern CRT aeRO PS AO Ps ctr Cb 228

1 Manuscript received by the Editor, 20 October, 1914.

172 ANNALS NEW YORK ACADEMY OF SCIENCES

, Page

POCLISSOGEACEVIA «a: odes hisysteusieveve eile ieaclavttevohelevstartetencla is fate MAIS oie Dake Gee Oe

UL Se revere rctete ouetetaciereve A COMIC COO OOS See pono Biso bob ofa. - 235

MAMI. Slayers elere ererel« le Be I OC EME OER enc a cA sine Oi 238

RHINOCCLOCIEH she cs Se cease lok elote steer tio ee oC eens aie ee eee 240

AT GLO MACE Aras eie wast tain oroiets le a ole oletoiors oe cuel epitope eel Ieee ea oe 241

Pigs Jana! WCCCALIES isle taisic exe cheseve oasis + cloles ole hele o hein e inion eee 241

FUUIITIATUGS eae tee ie ctepeh oteyei sued tsietst steie« Fe cee dyh ao loko SR ee 242

PrODOSCIMED . Sie ars eis, SF reefs) Posie nS te oy eicete eee tains Gh rete ere te eee eee 254

SUT OTT AN 67 ja, oe whe cereal S-oje ys foueco char aelle \e inftes apeFe feheks aeons teweiore bolted mevete ee shouetot ale toner oeetene 256

Condylarthra and, specialized \suceeSSors......2+-500 o20-+ssene es soe een eOm

HOM atayyer.) he chevete tobe teves ose love: csi Mews! eteve owniloletspere eso. ehayeerevavelione ie odetelevenene toleae vent 259

Marsupialia....... a ee OCR REC Ee OS COO DO Ono Cr 262

MON OEREMM ACA. os cys le tere allele ais ogote Sis cae ede Ghchsiete s eutin es estiee AG Uie Et ove E Te ene 270

Summary of the evidence from dispersal of land mammals.......... 270

Interpretation of negative evidence in fossil mammal faune......... 273

Dispersal of reptilia....... 5 Ae te ibre.tocies ere weeks we oseyalic reve lake awed tesegai eet TaiGh eee 274

Dinosauria...... sssduaile seuss eta ateberai’suabote cua ol shelekols wi eiejsbaeneue: ethaleiduelane suoWateustoumeee 275

(OL LOOUE heee airee RNA CIARA Ae Robina ieee eM TCT OR aE mee Ee cans care 6 280

CrOCOMTMART Ki. derok red. setete cicys e.os Clae je Sun steleliowje sietars else jyctale 'oreccle ete, aseporetees 284

TOS COT GUT A area lsratere etore ee cle, bree eve heac a fos oneicerauayenere beta obs, ote sete tells neds Lat velar Rotate 288

PISHEESAIU OF, MOUS eye bate toysites's: eulers' oles uci ew cella we te else ictie: eens Yon shelope borer etter: oxeiciedevastoeee, as) SePemeC ea ee

WISMELSAl OL sAIMP MUP ere .= epoca voters @) vie, ai cv recoie eieusle oe eheher shepelernslemey oer sper apcNorarenetete 294

PMispersal vot mresh=wabter f1SheSeyee tacts clove ciereoricle nie Serer tare te etere ote 297

General considerations on the distribution of invertebrates and plants.... 299

interpretation -of distribution data, of ierayiish; .).2 6 ©) ne ene 301

Distribution ot elias MOrtensis. .\. saosin oh oe clowns <>) da .cleeeeemee 303

DIS GED UGLOM TO te ee CICLO evens cotsicves svoncie)oieucliolerc¥ eters totete rots teier ~/eveuorstsicattel a eoeraaet eae 304

CricgicisMmeot, SOMETOPPOSLNE MhivIp OLNESES yei-weveyevere ciel aireeite seve) =e cues oleiene ou-patloueiiosellers 305

On vain speculations......... BHC R TR Oe OUEST EEE oman io ae oc 306

Summary of evidence....... ais echs Peta tin ar noner least ah omens rahe cue) SRE Poe CLAN cue eee Peete 308

FAD PEM GE |S ers Natoma le itctlete, eves ALORS SAGA RAE OR SA ic TEE BOERS enti Ct & 311

THESIS

1. Secular climatic change has been an important factor in the evolu-

tion of land vertebrates and the principal known cause of their present

distribution.

2. The principal lines of migration in later geological epochs have

been radial from Holarctice centers of dispersal.

3. The geographic changes required to explain the present distribution

of land vertebrates are not extensive and for the most part do not affect

the permanence of the oceans as defined by the continental shelf.

4. The theories of alternations of moist and uniform with arid and

zonal climates, as elaborated by Chamberlin, are in exact accord with

the course of evolution of land vertebrates, when interpreted with due

allowance for the probable gaps in the record.

MATTHEW, CLIMATE AND EVOLUTION 73

5. The numerous hypothetical land bridges in temperate tropical and

southern regions, connecting continents now separated by deep oceans,

which have been advocated by various authors, are improbable and un-

necessary to explain geographic distribution. On the contrary, the

known facts point distinctly to a general permanency of continental out-

lines during the later epochs of geologic time, provided that due allow-

ance be made for the known or probable gaps in our knowledge.

INTRODUCTION

ALTERNATIONS OF ELEVATION AND CLIMATE DURING GEOLOGICAL TIME

Several years ago,? I had the honor to give a talk upon “Climate and

Evolution” before the Linnean Society. The subject was then new to

me—it was an application to vertebrate paleontology of theories in

regard to geological history which had been brought forward by Cham-

berlin a year or two previously. I have had these concepts more or less

in mind ever since, and though I must admit that I am far from having

the evidence in shape for final presentation, I desire to submit for gen-

eral consideration the conclusions thus far reached.

Chamberlin’s theories are to-day well known and are year by year

gaining a wider acceptance. So far as they pertain to the present sub-

ject, they differ from the older prevailing concept of geological climatic

conditions chiefly in that they involve an alternation of climates through

the course of geologic time from extremes of warm, moist tropical and

uniform, to extremes of cold, arid zonal climates. The former are the

results of prolonged base-level erosion and the overflow of large conti-

nental areas by shallow seas. The latter are the results of the re-adjust-

ments needed to bring the continents once more into isostatic balance,

involving the general lifting of the continents, especially of their borders,

the expansion of the continental areas to their utmost limits and the

renewal of rapid erosion.

These alternations of conditions are marked by alternations of the

prevalent type of formation in the geological series. The uniform base-

leveling corresponds to widespread deposits of limestones and in its

waning stages with coal formations. The periods of uplift are marked

by thick barren formations, often red in color, by indications of arid

conditions in salt and gypsum beds and they finally culminate in great

extension of glaciers from boreal and high mountain areas.

2 Jan. 14, 1902.

’T. C. CHAMBERLIN: Jour. Geol., vols. v-viii. 1897-1901.

17a: ANNALS NEW YORK ACADEMY OF SCIENCES

Chamberlin’s text book of geology may be consulted, for the more exact

and extended exposition of these theories. The present purpose is to in-

dicate their application to the evolution of land vertebrates.

PERMANENCY OF THE OCEAN BASINS

In the first place, we may note that they depend as a fundamental

basis on the general permanency of the great ocean basins. The conti-

Fig. 1.

The areas within the continental shelf (100-fathom line) are left unshaded. This map

represents the true relations of land and water in the northern hemisphere far more

correctly than does the usual Mercator projection. The unity of Arctogzea and the direct

relation is obvious between the various degrees of isolation of the southern continents

and of peculiarity of their faune.

Zoological regions on north polar projection

nents have been alternately partly overflowed, separated and insular, or

raised to their greatest extent and united largely into a single mass. The

great ocean basins have in the main been permanent. This principle is

MATTHEW, CLIMATE AND EVOLUTION 175

dependent upon the known facts in regard to isostasy. The rocks under-

lying the oceans are heavier than those underlying the continents, as is

proved by the deficiency of gravity measurements in the continents as

compared with those in oceanic areas, the deficiency being most marked

in certain, mostly high-lying parts of the continents. The conclusion

appears unavoidable that in a broad way the present distribution of land

and shallow water on the one hand, of deep water on the other, has been

substantially unchanged.* Changes in past geography have been of two

kinds :

1) The continents have been alternately partly overflowed and then have

emerged to the limits of the continental shelf.

2) Certain lines of unstable conditions have been subject to folding and

crumpling, accompanied with great changes of level.

DISTRIBUTION OF LAND AND WATER, PRESENT AND PAST

The present distribution of land and water shows the great land masses

located mostly in the northern hemisphere.® The land areas, extended

to the borders of the continental shelf, form a single great irregular mass

with three great projections, South America, Africa and Australasia,

radiating out from it into the southern hemisphere. A rise of 600 feet

would unite all the land into a single mass.° Only New Zealand, Mada-

gascar, the Antilles and numerous small oceanic islands would remain

separate. The Kast Indian islands would be part of the main land. A

lowering of 600 feet would isolate North America, South America, Asia,

Africa and Australia as separate insular continents. Europe would

form a complex of islands and peninsulas much like the East Indies of

to-day. :

According to the present theory, we have recently passed through an

epoch of maximum continental extension and zonal climate culminating

in the Glacial age, marked by great aridity in the equatorial zones, by

cold and glaciation towards the poles and in high mountain regions. A

much earlier extreme of aridity and glaciation is seen in the Permian,’

and less marked extremes at the end of the Trias and at the beginning

and end of the Cretaceous. The alternate extremes of warm moist and

‘In this connection, however, the suggestion of Bailey Willis that the present isostatic

compensation may be unusually complete must be borne in mind.

° It should be observed that the Antarctic continent, according to the latest data avail-

able, equals or exceeds any of the other continents in bulk of emerged land: but it is sur-

rounded by deep oceans of vast extent.

® Australia forms a doubtful exception. The soundings in the Indo-Australasian

region are insufficient to determine with certainty whether or not there is any continu-

ous bridge within the 100-fathom line.

“The earlier Paleozoic extremes of aridity—-Cambrian and Devonian—do not come

within the scope of this discussion.

onditions of com-

rTXN

Wave

ACADEMY OF SCIENCES

ANNALS NEW YORK

Now the base-leveling and overflow con-

msion and growth of marine

The «

arrow border of the continental shelf will be unfavorable

2.—The southern continents, south polar projection

WiG.

1000-2000, and over 2000 fathoms indicated by progressive

’

The steep margins of the continental shelf

The isolation of the southern continents is in contrast to

at emergence of the continents will tend to

OF TERRESTRIAL FAUNAS

uniform climates are seen in the early Carboniferous, in the Jurassic,

mid-Cretaceous and Hocene.

and will tend to what Chamberlin calls restrictive evolution of faunas.

plete emergence of the continents and restriction of the littoral life to

ditions are obviously favorable to the exp

life, especially of the littoral and shallow seas.

the steep and n

176

x TYAN

S OX XY

RAY sa a RATE 970A Pr,

REARS

ea ar av

ROOK

Associated with the isolated continents, we have moist tropical uni-

form conditions of climate, and to this the provincial land faune of

Ocean depths of 100-1000

shading. Less than 100 fathoms unshaded.

are indicated by hachures.

EFFECTS OF ALTERNATIONS OF ELEVATION AND CLIMATE UPON EVOLUTION

flow and isolation will tend to the restriction of land migration and the

expansional evolution and cosmopolitan faunas, while their partial over-

development of provincial faune.

the unity of the northern land areas.

Conversely on land, the gre

MATTHEW, CLIMATE AND EVOLUTION wey

these periods will be especially adapted. The periods of continental

emergence were periods of arid and markedly zonal climate, and the

faune must adapt themselves to these conditions. Such conditions,

while favoring the spread and wide dis-

tribution of races, would be unfavora-

ble to abundance of life and the ease

with which animals could obtain a liv-

ing. The animals subjected to them

must maintain themselves against the

inclemency of nature, the scarcity of

food, the variations of temperature, as

well as against the competition of rivals

and the attacks of enemies. In the

moist tropical climatic phase, animals

would find food abundant and tempera-

ture relatively constant; but the larger

percentage of carbonic acid and prob-

ably smaller percentage of oxygen in

the atmosphere during those phases

would tend to sluggishness.

We should expect, therefore, to find

in the land life adapted to the arid cli-

matic phase a greater activity and

higher development of life, special

adaptations to resist violent changes in

temperature and specializations fitting

them to the open grassy plains and des-

ert life. Jn the moist tropical phase of

land life, we should expect to find

adaptations to abundant food, to rela-

tively sluggish life and to the great ex-

panse of swamp and forest vegetation

that should characterize such a phase

of climate.

The oncoming cold and arid condi-

tions should appear first at the poles

and spread towards the temperate and

tropical regions. Owing to the distri-

bution of the great land masses, this

would involve a general tendency for

the great migrations resulting from the

EAST INDIES

Central Asia

Asia Minor

Three pn

Cross-section of continental platforms and ocean basins at the equator

Vertical scale exaggerated about 170 times.

Mid-Atlantic

Ridge

Vertical scale greatly exaggerated.

America

Oross-section of continental platforms and ocean basins at 45° north latitude

North

Wie. 4,

Via. 3.

178 ANNALS NEW YORK ACADEMY OF SCIENCES

emergence of the continents to be outward from the two great northerly

masses, and especially from Asia. The tropical and southern continents

would be the refuge of the less adaptable and progressive types.

This phase of climate should, therefore, favor a higher development

and greater activity of land life, while the geographic conditions favor

cosmopolitan faunz. When the climatic pendulum began to reverse its

' swing, the continents became isolated and fheir faunw developed inde-

pendently ; but the dominant animals of these faune when first isolated

would be those previously developed during the arid phase, and these

would readapt themselves to the new conditions of moist and uniform

climate, of prevalent forest and swamp and of abundant food.

COMPARISON WITH THE PALEONTOLOGICAL RECORD

How far do these a priori deductions correspond with the facts, as

obtained from the geological record? In the first place, we should keep

in mind that our record of the land life of the emergence phases is very

defective. 'The sediments of this phase, where deposited along the con-

tinental margins, are limited in area, thick and very barren, the condi-

tions of their deposition being generally unfavorable to the preservation

of fossils. The sediments of the interior of the continents, river and

floodplain deposits of the Cenozoic era are more widespread and furnish

an extensive record of Tertiary and Quaternary land life; but those of

the preceding periods of aridity have been re-eroded and carried down

to the marginal and littoral areas during the period that has elapsed

since they were first deposited. Of the pre-Tertiary epicontinental de-

posits, only the coast margin, littoral and marine deposits are extensively

preserved. That means that the record of Mesozoic and Paleozoic land

life as preserved to us is chiefly the record of the coast-swamp and low-

land regions and that we know nothing of the life of the upland, except

by a rare accidental preservation. In considering the evidences of cli-

matic adaptation during the Mesozoic, this must be kept clearly in mind.

The great mass of evidence in favor of adaptation to progressively

arid climate and of dispersal from the northern land regions is derived

from the recorded history of the Mammalia during the Tertiary and

Quaternary and from comparison of their former and present geographi-

cal distribution. It has long been recognized that the present distribu-

tion of mammals is due chiefly to migration from the great northern

land mass, and the connection of this southward march with progressive

refrigeration in the polar regions was made more than a century ago

MATTHEW, CLIMATE AND EVOLUTION 179

(1778) by Buffon.* With a clearer perspective of geologic time and far

more exact records, it is clear that most of this deployment and dispersal

of the mammalian races has taken place since the Hocene epoch of the

Tertiary, although remnants of an older dispersal on the same lines are

probably traceable in the present habitat of monotremes, marsupials and

primitive insectivores.

INTERPRETATION OF SUPPOSED EXCEPTIONS

There has been a disposition in recent years among students of geo-

graphical distribution to lay weight upon certain apparent exceptions to

this general rule, where the geological record has not yet afforded evi-

dence to support the northerly origin of certain groups now limited to

the southern continents or to the tropics and to infer various equatorial

or southern continental connections during or previous to the Tertiary,

in order to account for these exceptions.® To these hypotheses, there are

several objections :

1) The evidence for the general permanence of the great ocean basins and

their maintenance formerly. as now, by isostatic balance is very strong and

direct, and before allowing any exceptions, we should be very sure that no

other explanation will serve.

2) The instances adduced in favor of former equatorial or southern con-

nections are distinctly exceptional cases in the faunz, which may, in all the

cases I have examined, be accounted for by appealing to the imperfection of

the geologic record, by parallelism or by the rare accidents of over-sea trans-

portation.

3) The existence of such land bridges would present the opportunity for

migration of other parts or of the whole of certain faunz, which bas evidently

not occurred. I can see no good reason why the only animals which availed

themselves of such continental bridges should be the ones which might be

accounted for in other ways, while those which would furnish conelusive proof

are invariably absent.

SSee K. y. Zittel, History of Geology and Paleontology, p. 43, for a brief summary of

. Buffon’s views on this subject. The theory has been more fully presented by many sub-

sequent writers. In recent years, it has been very ably set forth in its relations to

Tertiary mammalia by Dr. J. L. Wortman (Amer. Jour. Sci., 1903). A very readable

little pamphlet by G. Hilton Scribner, entitled ‘‘Where Did Life Begin’, 1884, while

totally deficient in geological perspective, sets forth very clearly the diverse effect upon

migration of the general trend of the great mountain system, north and south in the

New World, east and west in the Old. Alfred Russell Wallace is, I believe, usually

regarded as the foremost exponent of this theory on the distributional side: but it is

scarcely necessary to catalogue the principal exponents of a view so long and so gen-

erally held.

®The distinguished Argentine paleontologist, Florentino Ameghino, has for twenty

years past advocated a theory the direct opposite to that currently held, and he would

derive practically all groups of mammalia from a South American center of dispersal.

The evidence for and objections to this theory will be discussed in the sequel.

180 ANNALS NEW YORK ACADEMY OF SCIENCES

4) Many students of geographic distribution proceed on what appear to me

to be wholly false premises. They assume that the habitat of the most primi-

tive living member of a race is the original habitat of the race, the most ad-

vanced forms inhabiting the limit of its migration. It seems to me that we

should assume directly the reverse of this.

PRINCIPLES OF DISPERSAL

Whatever agencies may be assigned as the cause of evolution of a race,

it should be at first most progressive at its point of original dispersal,

and it will continue this progress at that point in response to whatever

stimulus originally caused it and spread out in successive waves of

migration, each wave a stage higher than the previous one. At any one

time, therefore, the most advanced stages should be nearest the center

of dispersal, the most conservative stages farthest from it. It is not in

Australia that we should look for the ancestry of man, but in Asia.

In the same way, in considering the evidence from extinct species as

to the center of dispersal of a race, it has frequently been assumed that

the region where the most primitive member of a race has been found

should be regarded as the source of the race, although in some instances

more advanced species of the same race were living at the same time in

other regions. The discovery of very primitive sirenians in Egypt while

at the same time much more advanced sirenians were living in Europe

has been regarded as evidence that Africa was the center of dispersal of

this order. It is to my mind good evidence that it was not. It is very

common to see references to the African facies of the Miocene or Pliocene

mammals of Europe; but it is much more correct to say that the modern

African fauna is of Tertiary aspect and is in large part the late Tertiary

fauna of the northern world, driven southward by chmatie change and

the competition of higher types.

The chief arguments advanced in support of the method here criticized

appear to be that the modification of a race is due to the changes in its

environment and that the primitive species are altered more and more

as they spread out or migrate into a new environment; but, assuming

that a species is the product of its environment, the conclusions drawn

would only hold true if the environment remained constant. This is

assuredly not the case, and if it were there would be no cause left for

the species to change its range. In fact, it is the environment itself,

biotic as well as physical, that migrates, and the primitive species are |

those which have followed it, while those which remained have had to

adapt themselves to a new environment and become altered thereby.

Probably, it is never the case that the environment of the marginal

MATTHEW, CLIMATE AND EVOLUTION 181

species is an absolute replica of the older environment of the race. In

many cases, it must be profoundly modified by its invasion of new regions,

and there are many features in the evolution of a race which appear to

be only partly, if at all, dependent on environmental change. But to

assume that the present habitat of the most generalized members of a

group, or the region where it is now most abundant, is the center from

which its migrations took place in former times appears to me wholly

illogical and, if applied to the higher animals as it has been to fishes

and invertebrates, it would lead to results absolutely at variance with

the known facts of the geologic record.

REVIEW OF THE EVOLUTION OF VERTEBRATE LIFE

To my mind, this hypothesis of the evolution of land life in adaptation

to recurrent periods of aridity supplies a satisfactory background of

cause for the whole evolution of the higher vertebrates.

We may set aside earlier periods of aridity and continental extension

signalized by the development of invertebrate land types, whose early

terrestrial adaptation is wholly hypothetical, since the known portion of

their history is so small and so remote from their origin that we cannot

project it backwards with any sort of exactness. As Barrell has pointed

out, the arid period of the late Devonian coincides with the probable time

of the first adaptation of vertebrates to terrestrial life. In the arid period

of the Permian, we see the conditions more clearly prevalent which

favored a much more extensive development of land life, and this period

marks the rise and early differentiation of the Reptiha. That reptiles

first differentiated from amphibia as a dry-land adaptation seems to be

obvious; that the period of their rise corresponded with the greatest ex-

treme of aridity, continental emergence and glaciation between Cambrian

and Quaternary would, I think, be also generally admitted. The domi-

nant order of land reptiles up to the close of the Mesozoic was the dino-

saurs, preéminently a dry-land adaptation in their inception, since their

most marked characteristic lies in their long limbs, bipedal progression

and general parallelism in proportions and structure to the large ground-

birds of modern times, which are to-day peculiarly inhabitants of arid

regions. The relationship and origin of the more specialized, mostly

gigantic, dinosaurs of the later Mesozoic can be best explained by regard-

ing them as a succession of derivatives from smaller and more lightly

constructed upland dinosaurs, mostly unknown to us, the larger and more

specialized types being re-adapted to a swamp life and inhabiting the

coast marshes whose sediments are still preserved, while the more direct

32 ANNALS NEW YORK ACADEMY OF SCIENCES

line of dinosaurian evolution inhabited the uplands, where the sediments,

if such were deposited, have long since been removed by erosion, and the

fauna is consequently unknown to us, except by inference. It is quite

impossible to trace the evolution of the dinosaurian phyla through the

same nearly direct series of known forms as can be done in the phyla of

Tertiary mammals. But I may observe that if our knowledge of the Ter-

tiary sediments were limited to the coastal ‘swamp deposits,—if in this

country, for instance, we knew only the Tertiary of the Atlantic and

Gulf coasts,—we would be equally at a loss for any direct ancestral series

illustrating the evolution of the Mammalia.

The same explanation, namely, that the geological record in the Meso-

zoie is defective where its evidence would be most direct as to the evolu-

tion of land vertebrates, applies both to birds and to mammals, but espe-

cially to the former. The exceeding scantiness of fossil birds and mam-

mals during the Mesozoic and their apparently sudden appearance in the

record, already well deployed, is often explained by supposing them to

have evolved mainly in some continent not yet investigated. It appears

to me that a simpler and more probable explanation lies in the fact that

the formations of the interior of the Mesozoic continents have in general

not been preserved and that this facies of the Mesozoic faunz is conse-

quently unknown to us.

It may be objected that remains of dry-land animals would be brought

down by rivers and deposited in their deltas and thus preserved to our

day. This may, of course, occur in exceptional cases. How rare is the

exception, we may judge from the exceeding rarity of remains of land

animals in true marine deposits, where the chances for their preservation

should be almost equally great.

In marked contrast with the evolutionary record among dinosaurs,

stands the record of development of the non-marine crocodiles and che-

lonians, whose normal habitat was the swamp regions and whose more

direct evolution is in consequence recorded since the Mesozoic. Remain-

ing in a constant environment, they evolved but little, though their abun-

dance and geographical distribution varied.

Throughout all the evolutionary history of the vertebrates, we see

numerous examples of races which, having become adapted to a higher

plane of life, have re-invaded a lower plane. In each instance, the higher

organization and greater activity acquired in the higher plane have caused

them to become dominant, increase rapidly in size and spread widely in

the absence of efficient competition. Thus we find various groups of ma-

rine reptiles appearing with apparent suddenness in the Mesozoic, becom-

ing very abundant and of gigantic size, spreading very widely and then

MATTHEW, CLIMATE AND HVOLUTION 183

being replaced by new invasions from the land instead of evolving further

in their new habitat. The ichthyosaurs, plesiosaurs, mosasaurs, sea-

crocodiles, sea-turtles, are examples of this sort among reptiles; the ceta-

ceans and seals among mammals. ‘These invasions from a higher to a

lower plane of active hfe have been very frequent, so that their recogni-

tion is necessary in tracing evolutionary series. The converse movement

from a lower to a higher plane, as from aquatic to amphibious, from

amphibious to terrestrial, from terrestrial to arboreal or aérial, have been

slow, difficult and for the most part have occurred but once or twice in

the geological history of vertebrate hfe. The higher field once occupied,

the lower adaptation was handicapped in its attempts to rise.

IMPERFECTION OF THE GEOLOGICAL RECORD

Everyone is familiar with Darwin’s classic illustration of the imper-

fection of the geological record ;'° but I doubt whether the majority of

paleontologists realize how very imperfect our record is, even to-day. We

know more about fossil mammals in’ proportion to their modern numbers

than about any other of the larger groups of land animals; yet the num-

ber of species of which we have any adequate knowledge is but a minute

fraction of the number which must have lived since the class first came

into existence. Were it not so, the fossil species would vastly outnumber

the living forms; as it is, they form a small minority. Moreover, the

greater number of recorded fossil species are hardly more than nomina

nuda, each known from a single fragmentary jaw, a tooth, a scale, a

broken bone, indicating indeed that an animal otherwise unknown lived

at a certain time in a certain locality but giving very little information

as to its entire structure, its habits, its geographical and geological range.

The relationships of these imperfectly known species, provisionally stated

by the describers and adopted without the query by subsequent writers.

are one of the most fertile sources of error in paleontological theories.

Mammals undoubtedly existed during the entire Mesozoic, an era about

three times as long as the Cenozoic. Two thirds of their evolution must

have taken place during that time; and by the end of it, the principal

modern orders were already defined. But we have not a skeleton, or even

a skull of a single Mesozoic mammal." Two jaws and a few teeth from

the Triassic, a number of more or less fragmentary jaws from the upper

Jurassic and various teeth and fragments of jaws from the uppermost

Cretaceous represent the sum total of our real knowledge of the first two

In the Origin of Species, at the end of Chapter X.

U Setting aside Tritylodon as of doubtful affinities.

184 ANNALS NEW YORK ACADEMY OF SCIENCES

thirds of the evolutionary history of the Mammalia. The rest is theory

and hypothesis.

Assuredly, we have no right to assume that the few species which have

been founded upon these fossil remains represent at all adequately the

number and variety of mammals that lived during the Mesozoic; nor can

we even suppose that they fairly represent them. Only two’’ of the

numerous phyla of early Tertiary mammals can be at all directly derived

from known Mesozoic ancestors. The rest are descended from unknown

forms. We may suppose, from the evidence at hand, that the known

Jurassic and Cretaceous mammals were arboreal swamp-dwellers and that

the chief reason why we know so little of the Mesozoic mammals is that

the deposits of the upland regions where they chiefly lived have not been

conserved to our day, or at all events have not been recognized and suffi-

ciently explored for fossils.

In the Tertiary, mammals suddenly spring into (apparent) promi-

nence, mainly, it may be assumed, because the fluviatile and eolian forma-

tions of the Cenozoic still exist in many localities, although they are being

rapidly eroded and carried down to the coastal swamp and sea margin

areas of deposition. Epicontinental deposits of Eocene age are rare and

scattered, and our knowledge of Eocene mammals is obtained from only

a few localities and largely from fragmentary specimens. Through the

following Tertiary epochs, these deposits become progressively more ex-

tensive and abundant, and our knowledge of fossil mammals is corre-

spondingly greater. Finally, in the Quaternary, they form a mantle over

most of the earth’s surface, and the fossil mammals are so well known

and so many specimens from so many localities have been found that we

can get a fairly accurate idea as to the range of many species, not merely

as discovered in one or another continent, but as to what parts of that

continent they inhabited. '

If our knowledge of fossil mammals is incomplete, that of fossil birds

is very much more fragmentary. They probably came into existence at

about the same time as mammals, but the early stages of their evolution

are even more obscure, and comparison of the living members of the class

affords less evidence than with mammals as to their source and course of

progress. They are even rarer than mammals in the Mesozoic. ‘Two

skeletons and a feather from the Jurassic of Bavaria, a number of skele-

tons and fragments from the late Cretaceous of Kansas and a few frag-

ments of the skeleton from Cretaceous formations in New Jersey and

Europe,—these are all we know of a class which was probably very large

12 Plagiaulacide and Didelphyide.

MATTHEW, CLIMATE AND EVOLUTION 185

and varied during the Mesozoic. Our knowledge of Tertiary and Quater-

nary birds is much more extensive, but it bears no comparison to our ac-

quaintance with Tertiary mammals, and the materials on which it is

based are for the most part very fragmentary, their identification often

questionable. We may say, however, that Mesozoic birds are more com-

pletely known than Mesozoic mammals; that is to say, we know the entire

skeleton of two or three, and in consequence can estimate their affinities

more certainly and exactly. On the contrary, the fraginentary remains

of Cenozoic birds make our estimates of their affinities proportionately

uncertain and inexact.

The Reptilia are a more ancient class than either birds or mammals

and include the ancestral types of both. Our knowledge of fossil reptiles,

in comparison with their probable numbers and variety, past and present,

is much less than with mammals, more than with birds. We cannot, as

with Tertiary mammals, reconstruct approximate evolutionary phyla of

the several races from known fossil forms; yet the evidence is sufficient to

give a reasonable basis for inferential phyla of some degree of exactitude

among many of the Mesozoic and Tertiary reptiles. But the origin of

the Reptilia, lke that of the Mammalia, is wrapped in obscurity, and the

interrelationship of the more ancient groups is a puzzle not yet solved.

We have a fairly extensive acquaintance with the Reptilia of certain

habitats at certain epochs; but there were evidently long intervening

periods and important faunal facies of which we know nothing or next

to nothing.

The Amphibia are not a very important group at present and are al-

most unknown as fossils, except for the so-called armored amphibians or

Stegocephalia, whose relations to the modern frogs, toads and salamanders

are still far from clear. This ancient group was abundant and varied in

Carboniferous, Permian and Triassic times and is supposed to have given

rise to the Reptilia; but the relationship has not been satisfactorily dem-

onstrated by fossils, nor is there direct evidence of the interrelationship

of the several groups of stegocephalians.

A wide gap separates the oldest four-footed vertebrates from any known

fishes, living or extinct.

ZOOLOGICAL REGIONS, Past AND PRESENT

The zoological divisions of the land surface of the earth are given by

Lydekker?® as follows:

18 RICHARD LYDEKKER: A Geographical History of Mammals. 1896. This is a modifi-

cation of the regions proposed by Sclater in 1858 (Jour. Proc. Linn. Soe., vol. ii, pp. 130-

146) and adopted by Wallace in 1876 (Geographical Distribution of Animals).

186 ANNALS NEW YORK ACADEMY OF SCIENCES

1. Australian region )

Polynesian fo ;

’ ms \ Notogewic Realm

Hawaiian

Austro-malayan “ )

Neotropical “| Neogieic

Malagasy

. Ethiopian 7

Oriental cs Arctogeeic

Holarctic 2

Sonoran

“cc “

oO 9

“

DEN

The Polynesian and Hawaiian regions have played no material part in

the evolution of mammalian faunas and do not call for any special con-

sideration here. The lmits of the remaining regions are shown on the

accompanying map. The eight principal “regions” are by no means

equally distinct, and their combination into three “realms” does not re-

move this defect. Of the five included in Arctogeea, the Sonoran is

closest, the Malagasy and Ethiopian farthest removed from the central

Holarctic region, if we take into account both the recent and extinct

faune. The true relations of the several regions might perhaps be better

represented thus:

Boreal Subregion

Nearctic Palearctic

ai Ei eel

Sonoran Holarctic Region Oriental Region

Subregion |

Mediterranean Austro-malayan

Subregion Subregion

Neotropical Ethiopian

Region Region

Malagasy Australian

Subregion Region

The Holarctic region in its broader sense, including the Sonoran and

Mediterranean subregions, is bounded by the tropic of Cancer, except

where (as in Asia) the dispersal of the fauna from a northern center has

been hindered by east and west mountain systems, or (as in America)

facilitated by north and south mountain systems. The Sonoran sub-

MATTHEW, CLIMATE AND EVOLUTION 187

region includes most of the United States and northern Mexico; the

corresponding subregion in the western half of the Old World is the

Mediterranean, including Europe south of the Alps and Pyrenees, part

of southwestern Asia and Africa north of the Sahara desert.

The Oriental region corresponds in the eastern part of the Old World

to the Mediterranean and Sonoran subregions, but, partly because it in-

cludes the great East Indian islands and partly because of the barrier

interposed by the Himalayan ranges, it is more clearly differentiated

from the Holarctic and may best be regarded as a region of itself.

eo NEOTROPICAL HOLARCTIC AUSTRALIAN

olarchie 7 Gene Mar cosmopolitan Anlelopes, Elphants Anlelopes, Horses, Herbivoraus and

MODERN dorms cay A few High er Fuminants Cattle, D Phi (BPA THR FT C Ma ial

Survivors of the Myomorph Frodents 2kle , Deer, Khinaceros Elephants, Dee arnivorous, 7Suplals

ulochthohous fauna| “Dogs, Cals, Bears (Fauna of Llivcene and Pleistocene Holarctica) A few Placentals

Giant Edenlates.| Man. Modern genera of) Elephants ,Cattle , Frit genera Flerbivorous and

PLEISTOCENE |2crauchenta a7 oi fiacental Mammals | PRhinoceroses , 7 Carnevorous

Toxadox. Holaretic | Mastodons, Elephants, \ Horses, Camels. of African TATHTNGLS Wr Z

Carnivor res 8 Ungulales| Horses , Riinocerases: arsupla Ss,

MIOCENE

OLIGOCENE

EOCENE

PALEOCENE

CRETACIC

Pic. 5.—Characteristic features of the mammal faune in different zoéloyical regions at

swecessive epochs of the Cenozoic

ORIENTAL ETHIOPIAN

Autochthonous Mostly modern genera

faur ra dointnant poy sisal Mammals.

Earliest invasion of Elephant: & Mastodons

5 J 7

Holarelic fauna FA iota Monkeys

Maslodons, E lephanis

Fhinocerases,

Gira, Beliss Ruminants

ed Horses eve

Peculiar lypes of \ Modern farilies of

Ungulales -E£aentates| Placental Mammals.

Marsuptal Carntvores) Mastodors. Monkeys

Mastodons

Rhinoceroses

Primitive Fuminanis

Masiodons ele.

Evolution of Evolution of modern »

Pec ue ‘ypes of families of placental

Peculiar Cypes of

Ungulales . Lnvasio

-Ungulates ele. nam mals

Primitive Placental\| Modern orders of

Ungulates. Placental Mammals

arsupial Carnivores| (: Ongulales, Carnivora, Primates

Primitive Placental

Carniveres and

Ongulates

Marsupials domimant

No Plaeentals posilt vely

Arzaw 72.

Austromalaya is the debatable ground between the Oriental and the

very distinct Australian region; but the consensus of opinion classes it

by preference with the Australian. It includes Celebes, the Moluccas,

Timor and smaller islands and is separated from the Oriental region by

“Wallace’s Line.”

The Australian region includes Australia, New Guinea and Tasmania

and is the most remote and archaic of all the great (continental) regions

of the globe. New Zealand is included in the Polynesian (island) region.

The Ethiopian region is connected with the Holarctic by the Mediter-

ranean subregion. It is perhaps more distinct than the Oriental, cer-

158 ANNALS NEW YORK ACADEMY OF SCIENCES

tainly less so than the Neotropical region. The Malagasy subregion is

related not to the modern but to the Tertiary Ethiopian region; its sup-

posed Oriental affinities will be considered later.

The Neotropical region is connected with the typical Holarctic through

the Sonoran, as the Ethiopian is through the Mediterranean interme-

diates; but the relationship is more remote. During the Tertiary, the

region was much more distinct than it is now.

In considering the records of past faune of one or another of these

regions as a guide to the dispersal of different groups, it is very necessary

to remember that our records are often chiefly or wholly from a small

part of the region, often far from typical.

Our knowledge of Palearctic faunze in the early Tertiary is wholly

from western Europe, an outlying, marginal part, more or less submerged

and archipelagic. Its relations to the main body of Palearctic land life

were probably much like those of the East Indian archipelago to the

continental portion of the Oriental region. In the later Tertiary and

Quaternary, we obtain a broader outlook on the Palearctic fauna, but

even then it is incomplete.

In the Oriental region, we know nothing of the land life of the early

Tertiary, and in the later Tertiary we know only the life of its northern

borders, close to the Palearctic region and doubtless more nearly approxi-

mating the Palearctic fauna then than now, as the Himalayan barrier

was less complete.

The result of these two facts will apparently be that the early Tertiary

Palearctic fauna will appear by the record to be less progressive than it

really was and that the Tertiary Oriental fauna will appear to be more

progressive than it really was. In the Nearctic Tertiary, the record is

chiefly confined to the Western plains; we know little of the Canadian

Nearctic—presumably more progressive. In the forested regions of the

Kast and South, where we might expect to find primitive survivals, or on

the Pacific coast, where we might expect to see stronger Palearctic influ-

ence, our knowledge is very imperfect, although the few available data

are in conformity with a priori deductions.

In the Neotropical region, our chief dependence is upon the Argentine

faune which should be both the most progressive and least influenced by

Northern immigration.

In the Ethiopian region, we have but a single glimpse of the Tertiary

land fauna, and that is derived from Egypt, where we might expect to

find a transitional fauna, combining true Ethiopian autochthones with

immigrants from Palearctic or northwestern Oriental faune. But, since

the water barriers to the north of Egypt were more extensive and the

MATTHEW, CLIMATE AND EVOLUTION 189

desert barrier to the south less developed in the early Tertiary than they

are to-day, we should expect that the autochthonic element would be

dominant and that Tertiary Egypt belonged to the Ethiopian zodlogical

region, although modern Egypt does not.

These may serve as instances of the caution with which the geological

record must be used in attempting to estimate the position and source of

regional faunz.

The regions here adopted are based primarily upon the present and

past distribution of mammals. Birds, reptiles, amphibians, fresh-water

fishes and the various groups of terrestrial invertebrates are not wholly

in accord with this arrangement so far as their present distribution is

concerned. This is partly because the means and limitations of their

dispersal differ, chiefly, as I shall attempt to show, because so little is

known of their former distribution.

ForMER BARRIERS AND BRIDGES

The general principle of dispersal on the lnes of the present continents

is open to an obvious objection. The outlines and connections of the

continents were different in former times. The relations of land and

water were not the same. In fact, if one depends upon a text-book knowl-

edge of geology he may find authority for an assured behef that they

were fundamentally and altogether different in different geologic periods.

It is necessary therefore to point out that the stratigraphic no less than

the life record is a defective one, and that the really proven changes in

the distribution of land and water are limited to those summarized on

page 175. The geotectonic hypotheses so ably and brilliantly elaborated

by Suess,’* Haug’® and other writers, are not facts but theories, and I

must confess to a decidedly skeptical attitude towards some of their con-

clusions. There are too many gaps in the chain of their arguments; too

many known facts with which their conclusions appear to be inconsistent.

The permanency of the continental platforms is indicated by the ab-

sence of abyssal deposits in their sedimentary succession wherever this

has been adequately studied. The platforms have been extensively over-

flowed by shallow seas, but such submergences were temporary, and inter-

vening periods of uplift are indicated by gaps in the marine succession.

Where the geologic records are fragmentary, widely scattered and imper-

fectly correlated, there often is a tendency to exaggerate the extent and

permanency of such overflows, as also to assume extensive unknown con-

tinents to account for the existence of clastic sediments which were more

44E. Suess: Antlitz der Erde. 1888-1901.

6H. Hauc: Traité de Geologie. 1912.

190 ANNALS NEW YORK ACADEMY OF SCIENCES

probably derived from unsubmerged adjoining portions of the existing

continents. We are apt to assume that great displacements of strata in-

volve correspondingly great changes of level. They do not necessarily ;

more probably, in most instances, the erosion has kept pace more or less

closely with the displacement. Even where great changes of level have

occurred, they often have been, and more often may have been, of re-

stricted extent and compensated by opposite changes in regions imme-

diately adjoining, and most of them have had but little extensive or

permanent effect on the general configurations and relations of the conti-

nental platforms.

The relative permanency of the North American continent is very

clearly brought forward in Schuchert’s maps.'® “Yet even here, if one

may venture a criticism on so thorough and conservative a study, there is a

certain loss of conservatism where the outlines run into territory where

the evidence is inadequate, as in the Antilles and the Arctic seas. The

imperfect data available for the South American continent appear to in-

dicate general conditions very similar to those of its northern neighbor ;

nor does it appear that Africa and Australia were any less permanent

land platforms. Northern Eurasia appears to have been similarly perma-

nent, but across Central Europe and extending southeastwardly to the

East Indies lies a broad strip of disturbance where great changes have

occurred during later geologic time. But the extent and permanency of

the great central sea which is so frequently depicted as interposing a

broad ocean between the Holarctic and the Ethiopian and Oriental land

masses is by no means certain, especially as regards its eastward exten-

sion. I cannot find in the recorded facts proof that it afforded any more

continuously effective bar to dispersal along the lines of the present con-

tinental relations than did the middle Cretaceous overflow in North

America or the early Tertiary one in South America.

Perhaps the most widely accepted departure from the permanency of

the ocean basins is the supposed Gondwana Land, invented to account

for certain similarities in southern Paleozoic floras, and since used to

account for almost all cases of similarity among southern flore and faune

which were not demonstrably due to dispersal from the northern conti-

nent. This theory has in its original form gone so long uncontested that

it is very generally regarded as incontestable. New discoveries have been

interpreted in terms of it, the weakness of the original evidence, the pos-

sibility that it might be otherwise interpreted, has been forgotten, and

like the Nebular Hypothesis, it has become almost impossible to dislodge

it from its place in the affections of the average geologist.

16 CHARLES SCHUCHERT: Bull. Geol. Soc. Amer., vol. 20, pp. 427-606, pll. xlvi-ci. 1910.

MATTHEW, CLIMATE AND EVOLUTION 191

If the distribution of animals be interpreted along the lines here advo-

cated, there is no occasion for a Gondwana Land even in the Paleozoic.

But it is chiefly as affecting Mesozoic or Cenozoic dispersal that we are

here concerned with it. One may summarize the arguments for it by

saying that a considerable number of groups of animals and plants which

are absent in the northern world, either living or fossil, are found in the

southern continents and some of them in certain oceanic islands as well.

Most of the groups are unknown or almost unknown as fossils; those

which have any considerable fossil record are steadily being eliminated

from the list by the progress of discovery, showing that they or their an-

cestors did formerly inhabit the northern world. The remaining groups

agree with those southern faunal groups which have admittedly come

from the north, in being of primitive and archaic type and in that their

representatives in the different southern regions are but distantly related,

the remoteness being in a very direct proportion to the present isolation

of the region.

There are a few instances of exclusively southern types closely related

(e. g., Galaxias) ; but, although they have been cited in corroboration of

the evidence from the groups above mentioned, they are in fact, if thus

interpreted, directly contradictory. For the distant relations of the one

series is interpreted to mean a very ancient connection, but isolation

since; while the other series would indicate a very recent connection and

earlier isolation. The explanation here lies not in a northern ancestry,

but that the ocean does not form an impassable barrier to their dispersal.

This has been proven in the case of Galazias; it is probably the explana-

tion of all similar distributions.

The relations of the Glossopteris flora are a different and far more com-

plex problem of distribution. The clue to its interpretation lies perhaps

in its association with Permian glaciation; but it is outside the limits of

the present essay and will not be discussed here.

REGIONAL CORRELATION

The geological correlation of widely distant formations is so intimately

bound up with problems of geographical dispersal and migration that the

two series of problems must needs be studied and solved together. We

cannot arrive at a correct understanding of the history and causes of the

geographical distribution of animals, present and past, without correct

correlation of the geological succession in different regions. Nor have

we, up to the present time, any reliable methods of exact correlation in

widely distant regions except the comparison of fauna and a considera-

192 ANNALS NEW YORK ACADEMY OF SCIENCES

tion of their source and the history of their migration and dispersal.

Absolute standards, as of world-wide changes in physical or climatic con-

ditions, may serve in the future to give us broad lines of correlation inde-

pendent of paleontology ; but at present their universality is hypothetical,

the exact train of physical phenomena which they entail and the indices

by which they may be recognized in the stratigraphic succession are im-

perfectly known. Paleontology is for the present our sole recourse in

correlation. Probably it will always be our chief dependence, at least in

exact and detailed comparison.

SYNCHRONISM AND HOMOTAXIS

The ordinary methods of paleontologic correlation can be applied with

accuracy and certainty only over limited areas of the earth’s surface.

When applied to far-distant regions, we meet first with the difficulty that

there is little identity of faune, only an equivalence more or less exact.

Nor can we be sure that equivalent or even identical forms were contem-

poraneous in all parts of the earth. They certainly are not so to-day.

The modern land fauna of Australia, as Huxley long ago insisted, is in

its broad lines a Mesozoic fauna. Examined in detail, it shows indeed

the marks of a long period of independent evolution and specialization.

Yet the degree and amount of specialization. is far less than that which

the faune of the northern continents have undergone during the Ceno-

zoic. The modern fauna of the East Indies or of Central Africa has a

great deal in common with the later Tertiary faunz of Europe and north-

ern Asia. Central America and tropical South America bear similar

relations to North America. While Huxley’s dictum that an older fauna

in one region may be homotaxial with a later fauna in another does not

apply to the extent of involving identity of all or most of the species, yet

it very clearly does apply in a broad way to the land faunz and probably

to a less extent to the marine faunz as well. The rate at which evolution

and differentiation progress varies as between the faunz of different re-

gions. It varies as between the different constituents of a fauna. Neither

the partial identity nor the general equivalence of two faune is sufficient

to prove them synchronous, except under certain conditions to be con-

sidered later.

Another method very generally used in correlation of faunz which

contain little or nothing in common consists in an estimate of their rela-

tive antiquity as indicated by the proportion of extinct to surviving spe-

cies or genera. This also involves the assumption that the rate of progress

wT. H. Houxupy: Q. I. G. S., vol. xviii, pp. xl-liv. 1862.

MATTHEW, CLIMATE AND EVOLUTION 193

of evolutionary change is constant in all parts of the earth, at least for

members of the same group. But if the rate varies in different regions

for the fauna as a whole, we have no reason to believe that it would be

constant for common or similar groups.

The practical application of this method is very unsatisfactory. In

illustration of this, I may instance the widely divergent views entertained

by different authorities as to the age of the later geological formations of

Argentina in comparison with European standards. Able and authori-

tative discussions of this problem have appeared within the last few years

by Ameghino,’* Roth,"® Gaudry,?° Scott,?* Hatcher,” Ortmann,”* Stan-

ton, von Ihering, Wilckens, Cossmann, Wiman and others, dealing with

the vertebrate and invertebrate fossils and stratigraphic relations of the

formations. The field work has been extensive, the collections large, the

faune are large and varied and in large part well known; but the results

are widely discordant. The amount of discordance is indicated by the

correlation of the four principal terrestrial formations, as given by

Ameghino, Roth, Gaudry and Schlosser.

The correlation of widely distant formations is so intimately bound up

with problems of geographic distribution and migration that the two

series of problems must be studied and solved together. The methods

relied upon by Roth and Ameghino are substantially the same as those

generally used by northern authors. Why then do they lead to such dis-

cordant results? It is because the data on which they rest prove not con-

temporaneity but homotaxis. Granting that two faune in widely remote

regions contain the same proportion of extinct species, granting that

they represent equivalent stages of evolutionary progress, they are not

thereby shown to be contemporaneous, unless they are at the same dis-

tance (measured not in miles but in difficulty of advance) from the main

center of dispersal of the fauna which they contain. Very obviously, if

iW, AMEGHINO: “L’Age des Formations Sedimentaires de Patagonie,’’ Anal. Soc.

Cient. Argent., tom. L, LIV; pp. 1-281 of separata. 1903. ‘“‘f’ormations Sedimentaires

du Cretacé Superieur et du Tertiaire de Patagonie,”’ Anal. Mus. Nac. Buenos Aires, tom.

Xv, pp. 1-568. 1907.

19 SANTIAGO RoTH: “Beitrag zur Gliederung der Sedimentablagerungen in Vatagonien

und der Pampasregion.’’ Neues Jahrb., Beil.-Bd. xxvi, s. 92-150, taf, xi-xvii. 1908.

20 A, GaupDRY: ‘‘Fossiles de Patagonie, etc.’”” Ann. de Paléont. I. 1906.

2 W. B. Scorr: Mammalia of the Santa Cruz Beds in Rep. Prine. Univ. Exp. Pata-

gonia, vol. v. 1903. Int. Cong. Zool., Berne, C.-R., pp. 241-247. 1905. A History of

the Land Mammals of the Western Hemisphere. 1913.

27. B. Harcuer: “On the Geology of Southern Patagonia.’ Amer. Jour. Sci., vol. iv,

pp. 827-354. 1897. ‘Sedimentary Rocks of Southern Patagonia,” ibid., vol. ix, pp-

89-108. Jbid., vol. xv, pp. 483-486. 1903.

23 A. ORTMANN: Tertiary Invertebrates in Report Prine. Univ. Exp. Patagonia, vol. iv,

pp. 45-332, pll. xi-xxxix. 1902.

See for further references the bibliography in Ameghino, 1907, supra, pp. 3-18.

194 ANNALS NEW YORK ACADEMY OF SCIENCES

TasBLeE I.—Correlation of the Four Principal Terrestrial Formations

Ameghino a || x

1906 4 Roth, 1908 Gaudry, 1906 | Schlosser, 1912

Pleistocene ) Pampean Pampean

I |

> Pampean (=

Pliocene | J

> Pampean ____________—|-

: | Santa Cruz

Miocene Santa Cruz :

eee J Santa Cr | Pyrotherium

Oligocene Santa Cruz

Eocene Santa Cruz | Pyrotherium | Pyrotherium | Notostylops

Paleocene Notostylops

Upper ee ne

Cretaceous Pyrotherium | Notostylops

ee Notostylops

4 c i]

the principal center of dispersal of Mammalia was in the Holarctic re-

gion, the fossil mammals in southern regions invaded by that northern

fauna will appear in their homotaxial relations to be more ancient than

they really are. The modern fauna of South America, of Africa, of the

Oriental regions, will be in the same stage of evolution as the late Ter-

tiary and Quaternary faune of Holarctica. Its species will be more

nearly related or equivalent to Pliocene and Pleistocene species of Europe

and North America than to their modern fauna. The late Tertiary

mammals of the southern continents will approximate in homotaxis the

middle or early Tertiary mammals of Holarctica; and the middle Ter-

tiary southern faune will approximate the early Tertiary or late Cre-

taceous faune of the north.

_ On the other hand, if we believe, as does Dr. Ameghino, that the prin-

cipal theater of evolution of the mammals lay in the temperate regions

of South America, and that the mammal population of the North was

derived by migration from that center (by way of Africa across a tropical

land bridge not now existing), it will be equally obvious that the southern

formations will be more ancient than their homotaxis, impartially con-

sidered, would lead us to believe. The result will be to assign to the

MATTHEW, CLIMATE AND EVOLUTION 195

Cretaceous period those southern faunze which are homotaxial with the

early Eocene of the North; to the Kocene those faune which are homo-

taxial with the Middle Tertiary of the North, and so on.

To a certain extent, the intercalation of marine formations may pro-

vide a check on this relationship, but it must be remembered that the

same theories of dispersal may also apply to marine faunz, wholly or in

part. Homotaxial marine faune may be far from contemporaneous.

The chief center of dispersal of marine faunze may be assumed to be

either the equatorial oceans and coasts, the northern, or the southern

seas, or both north and south equally. Only when the movements of dis-

persal are in opposite directions on land and in the seas will the marine

faunz furnish an adequate check on the homotaxis of land faunze; and

in that case the true synchronism must be arrived at by balancing con-

flicting evidence derived from terrestrial and marine faunal comparisons.

It is true that if we eliminate the idea of faunal dispersal altogether

and regard each race of animals as evolving and dispersing independ-

ently, governed by its own conditions and causes of change, we may in

the present imperfect state of our knowledge lay out various and inde-

pendent centers of dispersal for different races, whose successive appear-

ance in one or another continent will furnish data for a true correlation.

There has been a strong tendency in the last half century to work on this

theory, but in the present writer’s opinion at least, the supposed evidence

in favor of this view is due chiefly to the imperfection of the geologic

record, and its very wide acceptance to a lack of appreciation of the

underlying causes of evolutionary progress and dispersal.

I do not understand how anyone can reconcile the theory that each

race of animals evolves and disperses independently and that the common

biotic and physical environment is not a controlling factor, with the plain

fact that regional faunz do exist to-day. The conditions that control the

dispersal of one race are largely identical or correlated with those that

control the dispersal of others, and every change in these conditions will

affect not one race only, but a large part or the whole of a fauna, in a

manner and to a degree largely identical, causing similar changes in the

range of the fauna.

‘

TERTIARY CORRELATION IN SOUTH AMERICA

Before setting forth the evidence as to the dispersal of the mammals,

it is necessary to attack a problem which has caused much acrid contro-

versy, namely, the age of the later formations of the Argentine Republic.

The difference of opinion among authorities has already been indicated,

196 ANNALS NEW YORK ACADEMY OF SCIENCES

as also the fact that the true correlation is so intimately related to the

direction of migration that the two problems must be settled together.

In view of the great and well merited reputation of Dr. Ameghino and

the immense array of data which he has marshalled in support of his

theories of correlation and phylogeny, it is not surprising that they should

find a very considerable acceptance, not in South America alone but else-

where. Few scientists indeed are disposed to accept his derivation of the

horse family from carly South American ancestors or of the various

families of Carnivora from the same source, for in these and other cases

the evidence for northern ancestry is almost universally accepted as con-

vineing; but many writers are willing to accept Ameghino’s determina-

tion of the age of the Argentine formations, although more critical as to

his phylogenetic views.

The two, however, must stand or fall together; and it is precisely be-

cause the Equidwe, Procyonide, ete., if their generally accepted phylog-

enies be admitted, afford incontrovertible evidence against the validity

of Ameghino’s correlations of the formations of the Argentine, that he

has been compelled to devise different phylogenies for these cases. Few

scientists will be willing to believe Ameghino’s assertion that Merychippus

and its successors in the equine phylum have nothing to do with the

Anchitheriine which they so closely resemble in teeth, in skull, in feet,

in all details of the skeleton, but must be derived from the South Amer-

ican Notohippide on the strength of a much more distant resemblance in

the second upper molar, unsupported by any near resemblance whatsoever

in the remaining teeth or in any points of construction of skull or of

skeleton. It is not my intention to present here any detailed refutation of

Dr. Ameghino’s argument, but to point out that if the northern origin

of the Equide be accepted, the age of the Pampean and related forma-

tions must be far later than that he has assigned to them. The first ap-

pearance of true equines in South America is in the Pampean. The

three best-known genera are Lquus, [ippidion and Onohippidion. The

first might be regarded as of Palearctic origin; the second and third have

no Old World predecessors, but may be directly derived from the North

American Pliohippus. They are, however, much larger and more pro-

gressive than Pliohippus, and. in size, reduction of the lateral digits, etc.,

are equivalent to Hyuus. We can hardly doubt that they came to South

America from North America, nor can I see any practical alternative to

believing that Hquus arrived by the same route. Now, the first appear-

ance of Hquus in North America is at the base of the Pleistocene. In

Argentina, it first appears in the middle Pampean. The middle Pam-

pean cannot therefore be older and is presumably younger than Lower

MATTHEW, CLIMATE AND EVOLUTION 197

Pleistocene. Hippidion and Onohippidion are found (fide Roth) in

somewhat older levels; but as they are much advanced over anything in

our Middle Pliocene (Blanco), it would seem that their first occurrence

in the Pampean must be placed at the top of the Pliocene or preferably

in the lower Pleistocene. I conclude that the Pampean formation ap-

proximately represents the Pleistocene epoch.

Beneath the Pampean of Ameghino, but included in it by Roth, are

fossiliferous beds in which certain Procyonide and Urside are found.

If we admit the North American source of these carnivora, they would

indicate Pliocene age for the beds containing them. Dr. Ameghino, who

regards them as Oligocene and Miocene, is compelled, therefore, to set

aside the North American ancestors of the Procyonide and to regard

them as of South American origin and the Urside as either autoch-

thonous or arriving in South America from the Old World via Africa.

As with the Equid, the only shadow of plausibility for such phylogenies

lies in the incompleteness and careful limitation of the evidence that is

adduced in their behalf. Phlaocyon of the North American Miocene,

which is intermediate between Cynodictis and the Procyonide in almost

every detail of the perfectly preserved dentition, skull and skeleton is

merely** “un vrai Canide sans relations avec les Procyonidés,” while the

South American genera are derived through hypothetical ancestors from

the carnivorous marsupials of the Santa Cruz. Here again, Dr. Ameghino

is compelled, in defense of his theories of correlation, to adopt these im-

possible phylogenies, because if the Procyonide are of North American

origin the Argentine formations are demonstrably of later date than

those which he assigns to them. Phlaocyon is a far more primitive

procyonid than any of the South American genera. Leptarctus of the

Upper Miocene may be their equivalent, but it is very imperfectly

known.” If these Argentine genera are derived from the Oligocene

Cynodictis and related genera of Holarctica, Phlaocyon being about half

way between the two groups, then their age is indicated as Pliocene, not

as Oligocene or Miocene. Also with the Urside; to admit them as arriy-

*4 PL, AMEGHINO: Ann. Mus. Nac. Buenos Aires, tom. xv, p. 396. 1906. Dr. von Ihering

has since attempted to prove what Ameghino merely asserted. His argument rests upon

an untenable interpretation of a single feature in the dentition, ignoring all other char-

acters of teeth, skull and skeleton, and, if true, would involve not only that Bassariscus

has nothing to do with the Procyonide (which he asserts), but also that the Procyonide

have nothing to do with the carnivora but are of wholly diverse ancestry.

See H. vy. IHERING, Systematik, Verbreitung und Geschichte der sudamerikanischen

Raiibthiere. Archiv f. Naturg., 76 Jahrg. I. Bd., s. 113-179. 1910.

°>'The type of Leptarctus is an upper premolar of doubtful affinities. Wortman re-

ferred to it in 1894 a lower jaw from the Upper Miocene, which is unquestionably

procyonid and hardly distinguishable from Procyon. Ameghino and von Ihering ignore

this record.

198 ANNALS NEW YORK ACADEMY OF SCIENCES

ing via North America would compel Ameghino to conclude that their

first occurrence in South America in these same sub-Pampean beds must

be materially later than the evolution of the phylum in the Palearctic

region (Miocene) and that the genus Arctotherium of the true Pampean

in South America, unknown in North America until the Pleistocene,

indicates, like Hquus, that the Pampean is a Pleistocene formation.

The distribution of Smilodon in North and South America is in exact

accord with that of Arctotherwm. The relations of the South American

Proboscidea to those of North America correspond to those of the Equide.

The Camelide, Cervide, Canide, ete., also support the Pleistocene age

of the true Pampean. The Edentata, whose migration appears to have

been in the reverse direction, will be discussed later.

In the Santa Cruz fauna, we have not the direct evidence that the

Pampean faune afford for correlation by means of groups of admittedly

northern origin. The evidence has been very fully discussed by Hatcher,

Ortmann, Scott and others, and so far as it is based upon the relations

and age of associated marine formations, I am not competent to criticize

it. The criterion used by Ameghino and Roth, of proportions of extinct

to living genera, I regard as untrustworthy, partly for the genera] reasons

already given (p. 192) and partly because of the personal equation that

must always affect the number of genera and species described as new,

as compared with those referred to known genera and species. Unless

the standards of diversity for genera and species were approximately the

same, and in this instance they are certainly very wide apart,”° the com-

parison of the proportions of extinct to surviving genera and species in

Argentine formations with those of Europe or North America would be

misleading.

Perhaps the most important correlation is that of the Notostylops

fauna, Lower Cretaceous according to Ameghino, Upper Cretaceous ac-

cording to Roth, Paleocene according to Gaudry, Upper Eocene in Schlos-

ser’s view. Here there is an apparently strong point for Cretaceous

age in the presence of dinosaurs in association with the fossil mam-

mals. Dinosaurs disappeared from the Northern world at the end of

the Cretaceous." They are entirely unknown in any Tertiary formation.

Nevertheless, the possibility of their survival into the early Tertiary in

South America must be considered.?8 The mammalian fauna with which

°6The European fossil rodents are, for the most part, referred in accordance with the

old conservative standards of genera and species, while Ameghino is much inclined to

hairsplitting in generic and specific distinctions. Scott in his revision is more conserva-

tive, but not so as to equalize the standards in question.

*7 The latest dinosaur formations of North America are, however, regarded as Paleo-

cene by Knowlton, Lee, Peale and other authorities.

* The same arguments apply to the occurrence of a Mesozoic type of Crocodile,

Votosuchus, in the Notostylops fauna.

MATTHEW, CLIMATE AND EVOLUTION 199

they are associated is in part closely related to the Paleocene fauna of

Europe and North America and for this reason has been regarded as

equivalent. But these genera of Northern affinities are associated with

a large number of larger and more progressive genera, structurally de-

rivable, according to the canons of evolutionary development universally

accepted by paleontologists, from the more primitive types which are

common to the Notostylops beds and the Paleocene of the North, and

leading apparently into the various specialized groups peculiar to the

later South American Tertiaries. These more progressive types are un-

known to any northern Tertiary fauna; they appear to be derived from

the more primitive group whose affinities are so close to the Puerco,

Torrejon and Cernaysian mammals; and they point to the conclusion

that the Notostylops fauna is in reality decidedly later than the Paleo-

cene, the more primitive group of its fauna being little altered survivals,”®

corresponding to the primitive survivals (Condylarthra, ete.) which are

found in the Wasatch and Wind River faunz of North America. Taking

the Notostylops fauna as a whole, it appears to me to represent an Hocene

stage of development, conditioned by an isolation which began in the

Paleocene and hence prevented the incoming of any Perissodactyla,

Artiodactyla or Carnivora from North America.*° This same isolation

will satisfactorily account for a later survival of the dinosaurs, of Meso-

zoic Crocodilia and some other primitive elements, if they were in fact

contemporary with the Notostylops fauna.

The age of the Pyrothertwm beds is much less definitely determinable.

Dr. Roth, indeed, doubts the existence of this fauna as distinct. If

accepted, it would presumably be intermediate between the Notostylops

and Santa Cruz faune and provisionally referable to the Oligocene.

The sequence of the Argentine faune will then be

Pampean (s.s.) — Pleistocene

Monte Hermoso etc. — Pliocene

Santa Cruz — Miocene

Pyrotherium — ? Oligocene

Notostylops — Eocene.

So far as the correlation of the Pampean and Santa Cruz is concerned,

their fossils agree wholly in preservation and degree of petrifaction with

those preserved in similar Pleistocene and late Miocene formations, re-

°® Little altered, that is to say, so far as the parts known to us are concerned; their

adaptation, whatever it was, not involving radical changes in dentition from the primary

type.

*® Schlosser (in Zittel’s Grundziige d. Pal.. Rey. Ed. 1912) regards the Notostylops

fauna as Upper Eocene. Scott (History of Mammals of West. Hem.) places it as Eocene.

2()() ANNALS NEW YORK ACADEMY OF SCIENCES

spectively, in the western Plains, and the degree of consolidation of the

matrix is the same. We have in the West two fossiliferous formations,

the Bridger (Eocene) and John Day (Oligocene), which are, like the

Santa Cruz, composed of an andesitic volcanic ash, and similar ash strata

are found in different levels of our Western Miocene formations. Now,

the Santa Cruz matrix and fossils are very much less consolidated or

thoroughly petrified than the Bridger and“decidedly less so than the

John Day, while they agree very well with the volcanic ash beds in the

middle and upper Miocene. As there is no reason to suppose that the

rock-making processes work at a different rate in different continents,

this evidence is entitled to some consideration. On similar grounds, the

Pampean fossils would be referred to middle Pleistocene, and the few

fossils that I have seen from Monte Hermoso agree best with Pliocene

fossil mammals from North America. I should place no weight on this

kind of evidence except when, as in the present instance, the climatic

conditions and the origin and method of deposition of the formations are

substantially similar.

The foregoing digression is somewhat outside the limits of this dis-

cussion. It appears, however, to be necessary to show briefly the reasons

on which the age assigned to the South American mammalian faunz are

based. It might, indeed, be logically objected that these correlations

are based on the northern origin and migration of certain phyla and

cannot, therefore, be used in support of the theories here advocated. But

the phyla on which the demonstration rests are so universally admitted

to have arisen in the north, and the evidence that they did so is so com-

plete and conclusive, that there is no reasonable alternate to accepting

them as such. And if so, the correlations of South American faune

must be approximately as here stated, a conclusion supported by the

wholly independent evidence of the degree of consolidation of the forma-

tion and of petrifaction of the fossils contained.

CENTERS OF DISPERSAL

Whether the evolution of a race be regarded as conditioned wholly by

the external environment or as partly or chiefly dependent upon (un-

known) intrinsic factors, it is admitted by everyone that it did not

appear and progress simultaneously and @quo pede over the whole sur-

face of the earth, or even over the whole area of a great continent. The

successive steps in the progress must appear first in some comparatively

limited region, and from that region the new forms must spread out,

displacing the old and driving them before them into more distant

MATTHEW, CLIMATE AND EVOLUTION 2()1

regions. Whatever be the causes of evolution, we must expect them to

act with maximum force in some one region; and so Jong as the evolution

is progressing steadily in one direction, we should expect them to con-

tinue to act with maximum force in that region. This point then will

be the center of dispersal of the race. At any given period, the most

advanced and progressive species of the race will be those inhabiting

that region; the most primitive and unprogressive species will be those

remote from this center. The remoteness is, of course, not a matter of

geographic distance but of inaccessibility to invasion, conditioned by the

habitat and facilities for migration and dispersal.

If the environmental conditions in the center of dispersal pass the

point of maximum advantage for the race-type that 1s being developed

and become unfavorable to its progress, we should find its highest types

arranged in a circle around a central region, which was the former point

of dispersal, and the more primitive types arranged in concentric ex-

ternal circles. The central region will be unoccupied, or inhabited by

specialized but not higher adaptations.

It would appear obvious that the present geographic distribution of a

race must be interpreted in some such way as this by anyone who accepts

the modern doctrine of evolution. Yet there are many high authorities

on geographic distribution who proceed apparently upon a precisely op-

posite theory. According to these authors, the distribution center of a

race is determined by the habitat of its most primitive species, and the

highest and most specialized members of the race are most remote from

its center of dispersal. This principle may be true enough so far as

concerns the first appearance of a given race, 1. e., provided the most

primitive species are also the oldest geologically; but it appears to me

to be the direct reverse of fact as regards the present distribution, or the

distribution at any one epoch of the past. The only ground on which it

could be defended would be that the progress of the race is due to its

migration, and those members which did not migrate did not progress.

But this involves the view that its progressiveness up to the time that

its geographical environment changed was due to staying at home, and

the same progress after its environment changed was due to not staying

at home. It seems to me that the prevalence of this view must be due

to some fallacious notions about migration, unconsciously retained, in-

volving a concept of it as analogous to travel in the individual. The

successful business man, no doubt, may pack up his baggage and take to

traveling, leaving home and going elsewhere and profiting much thereby.

Nations have done the same thing, likewise to their advantage. But

there is very little analogy here to the zodgeographic migration of spe-

202 ANNALS NEW YORK ACADEMY OF SCIENCES

cles

rectly of transference of habitat, although this may be the final result.

It seems obvious that the conditions which brought about the early

progressiveness of the race in a particular locality would, so far as they

which is a question of expansion or contraction of range, not di-

were external, cause the continued progressiveness of those individuals

which remained in that region; so far as they were intrinsic, they would

affect the main bulk of the race, the center of its range, more than any

outlying parts of it. The present writer is very thoroughly convinced

that the whole of evolutionary progress may be interpreted as a response

to external stimuli; and intends here to point out what he regards as the

most important of these stimuli. It is therefore necessary to point out

that these postulates regarding centers of dispersal and migration are

not dependent upon the theories to be proved—we are not reasoning in

a circle.

OCEANIC AND CoNTINENTAL ISLANDS

FAUNAL DIFFERENCES BETWEEN OCEANIC AND CONTINENTAL ISLANDS

One of the strongest arguments for the relative permanency of the

deep oceans, especially during Cenozoic time, is afforded by the marked

and striking contrast between the faune of those large islands which are,

and those which are not, included within the continental shelf. The

continental islands have the fauna of the continents to which they belong,

large as well as small, differing only in the absence of types of recent

evolution or of unsuitable adaptation and in the survival of primitive

types which have disappeared from the mainland. But no question could

be raised as to their former union with the mainland, no other possible

solution would explain their fauna. We are compelled to assume the

former connection of the British Isles with Europe, of Ceylon with India,

of Japan with Korea or Siberia, of Sumatra, Java and Borneo with the

Malayan mainland, of the Philippines with Borneo, of New Guinea and

Tasmania with Australia, of Newfoundland and Cape Breton with Lab-

rador and Nova Scotia. In each and all of these cases, the evidence is

overwhelming, and, with the exceptions cited, the faunal identity is

complete. .

On the other hand, with all those islands which are separated by deep

ocean from the mainland, we find that just that evidence is lacking which

would afford convincing proof of former union with the mainland. Their

faune are widely different from those of the adjoining mainland; they

lack just those animals which could not possibly have reached there

except by land bridges; they point often to long periods of independent

evolution and expansion, and the primary elements of the faune of every

MATTHEW, CLIMATE AND EVOLUTION 203

one of them are such as might possibly at least have reached the island

without continental union, whether by accidental transportation, by

swimming or by other means.

Take for example the mammals of Sumatra, Java and Borneo. We

cannot reasonably suppose that the rhinoceroses, tapirs, deer, wild dogs,

felids and numerous other large animals common to them and the ad-

joining continents reached these islands except by land. They are too

large for transportation on “rafts” of vegetation such as occasionally

drift to sea from the mouths of tropical rivers. They are dry-land ani-

mals not given to swimming long distances. And we would not invoke

the agency of man to account for a whole fauna. But most important

is the fact that all the animals that we might fairly expect to find there

in view of a former land connection are really present.

Contrast with this the fauna of Madagascar.* There are no ungulate

mammals there, except for the bush-pig, possibly introduced by man (in

accord with known customs of the Malays) and a pigmy hippopotamus

(now extinct) which might have reached the island by swimming, as

hippopotami are known to travel considerable distances by sea from one

river mouth to another. The great majority of the unguiculate groups

of the mainland are also absent. The only representatives are a few

very peculiar carnivores of the family Viverride, a peculiar group of

insectivores (Centetide) and a peculiar group of Cricetine rodents, each

apparently evolved on the island from a single type introduced Jong ago,

a species of shrew (Crocidura) of more recent introduction and a variety

of bats. There are numerous lemurs and no monkeys there; and the

lemurs appear to have radiated out from a single group*? into a

number of peculiar types, two of which, now extinct, paralleled the

ungulates and the higher apes in several significant features. ‘The fauna

of the island does not resemble the present fauna of Africa, nor can it

be derived from any one past fauna, known or inferential, of that conti-

nent. The attempt to derive it from the present or from any known or

inferential past fauna of India involves still greater difficulties. On the

contrary, the Malagasy mammals point to a number of colonizations of

the island by single species of animals at different times and by several

methods. Of these colonizations, the Centetide are the earliest, perhaps

pre-Tertiary ; the lemurs, rodents and viverrines are derivable from one

or more middle Tertiary colonizations: and in both cases the “raft”

31A,. R. Watuace: Island Life, pp. 381-412. 1881. See also Trouessart Catalogus

Mammalium and Suppl. Quing.; Lydekker, Geog. Hit. Mam., pp. 211-226. 1896. Lydek-

ker’s arguments for continental union are mostly invalidated by more recent discoveries.

32 See W. K. Gregory's studies upon the affinities of the Lemuroidea, forthcoming in

Amer. Mus. Bulletin.

204 ANNALS NEW YORK ACADEMY OF SCIENCES

hypothesis may reasonably be invoked.** The hippopotami may have

arrived by swimming and the bush-pig and the shrew may have been

introduced by man, while the bats may readily have arrived by flight.

The extinct ground birds are easily derived from flying birds.

Dr. Arldt,** in his discussion of the Malagasy fauna, poimts out its

composite character, derived from severak successive invasions. This, I

think, is clear enough; but it seems equally clear that these were not

faunal invasions due to land connection but sporadic colonizations by a

few species all at different times. The characters of the mammalian

fauna, both negative and positive, practically exclude the theory of land

connections during the Tertiary.

The West Indian islands afford another marked instance. In spite

of its nearness to Florida, there are no North American mammals in

Cuba, except the manatee,—analogous with the hippopotamus in Mada-

gascar. Nor are the other islands richer in fauna. As also in Mada-

gascar, we have a peculiar and very primitive insectivore Solenodon

(Cuba and Hayti), a number of peculiar extinct ground-sloths, of which

Megalocnus is the best known, and which although Pleistocene in age

are derivable not from the Pliocene or Pleistocene ground-sloths of North

or South America but from the Miocene ground-sloths of Patagonia,

and evidently differentiated through a long-continued period of isolated

evolution, and a couple of chinchillas—the hutias of the larger islands,

the (extinct) Amblyrhiza in Anguilla. The Solenodon may be referred

to a more ancient colonization, the ground-sloths probably arrived during

the Miocene, the chinchillas more recently; and the direction of the

prevalent ocean currents points out the reason why these are of South

American derivation. Those who, hke Dr. J. W. Spencer,*® believe in

gigantic elevation movements connecting the Antilles with the mainland

in Pliocene and Pleistocene would account for the absence of the conti-

nental fauna by invoking a subsequent subsidence which drowned out

everything else. The improbabilities involved in this hypothesis on strati-

graphic and faunal grounds have been pointed out by W. H. Dall, R. 'T.

Hill’® and others.

*3'The moist tropical conditions of early Tertiary times would fayor the formation of

such rafts, the small size and arboreal habits of the animals concerned would increase

the chances of their being caught on such rafts and the uniform climate and conse-

quently more placid seas would increase the distance over which the raft might be trans-

ported before it broke up.

*' THEODORE ARLDT: Entwicklung der Kontinente und ihrer Lebewelt, pp. 119-142.

1907.

° J. W. Spencer: “Reconstruction of the Antillean Continent,” Bull. Geol. Soc. Amer.,

vol. vi, pp. 103-140. 1895.

38 W. H. DALL: “Geological Results of the Study of the Tertiary Fauna of Florida,”

Trans. Wagn. Inst., vol. iii, pt. vi. 1903.

R. T. Witu: “Geological History of the Isthmus of Panama and Portions of Costa

Rica,” Bull. Mus. Comp. Zo@l., vol. xxviii, pp. 151-285. 1898.

MATTHEW, CLIMATE AND EVOLUTION 205

Cuba, while near in actual distance to the North American continent,

has been comparatively inaccessible to sporadic colonization from that

source, on account of the direction of the ocean currents; but coloniza-

tions from South (or possibly Central) America have reached it. New

Zealand is more remote and inaccessible, and, during the whole Mesozoic

and Cenozoic eras, we have evidence of but two colonizations by land

vertebrates, neither implying any necessary continental connection. The

rock-lizard (Sphenodon) may, for aught we know to the contrary, be

derived from a marine form; all its early Mesozoic relatives were aquatic,

some apparently marine. The few other reptilia may be best accounted

for by sporadic colonizations of later date. The moas are probably de-

rivatives from flying birds.

When we come to the smaller oceanic islands, their poverty of fauna

is still more conspicuous. If their fauna is due to sporadic colonization,

this should be expected, as the chances are reduced directly in proportion

to the smaller length of coastline on which an immigrant might land, as

well as by their effective distance from the mainland. The colonization

of a group of islands one from another may be due to former land con-

nection and subsequent isolation, or to the same method of accidental

transport, subject to the same laws of chance.

It is quite possible that in certain instances the small size and unfa-

vorable environment of islands formerly connected with the continent

may account for non-survival of the continental fauna. The Falkland

Islands are a case in point; but even here, we find the survivors closely

allied to the continental fauna and including types which afford the con-

clusive proof of continental connection which is uniformly lacking in

oceanic islands.**

The characteristics of continental and oceanic island faunz have been

very fully and ably elucidated by Wallace (Island Life), and it is in-

tended here merely to assert that the progressive increase of our knowl-

edge of the past life of the world tends only to emphasize the distinctions

in the source of their faunze which he has so clearly demonstrated and,

so far as my acquaintance with the subject goes, to reduce still further

the number of continental connections which he regarded as permissible.

To the argument so often advanced that the transportation of a species

across a wide stretch of sea and its survival and success in colonizing a

new country in this way is an exceedingly improbable accident, it may

be answered that, if we multiply the almost infinitesimal chance of this

*7 Introduction of Canis antarcticus by human agency in prehistoric times is, however,

a possible explanation of its occurrence. It is the only alternate to a Pleistocene land

connection.

206 ANNALS NEW YORK ACADEMY OF SCIENCES

occurrence during the few centuries of scientific record by the almost

infinite duration of geological epochs and periods, we obtain a finite and

quite probable chance, which it is perfectly fair to invoke, where the

evidence against land invasion is so strong. Furthermore, the fact that

continents have not in general been peopled in this way one from another

is well accounted for by the fact that speties already existed there which

filled the place in the environment and by their competition prevented

the new form from obtaining a foothold, or greatly reduced the chances

thereof. In oceanic islands, however, the favorable environment existed

without the animal to fill it. Very often, on account of this lack, some

other type was evolved to fill its place; birds being widely distributed on

account of their powers of flight have in many oceanic islands developed

large terrestrial adaptations to take the place of the absent or scanty

mammals.

NATURAL RAFTS AND THE PROBABILITIES OF OVER-SEA MIGRATION

THEREBY

The following series of facts and assumptions may serve to give some

idea of the degree of probability that attaches to the hypothesis of over-

sea transportation to account for the population of oceanic islands.

1) Natural rafts have been several times reported as seen over a hundred

miles off the mouths of the great tropical rivers such as the Ganges, Amazon,

Congo and Orinoco.* For one such raft observed, a hundred have probably

drifted out that far unseen or unrecorded before breaking up.

2) The time of such observations covers about three centuries (1 set aside

the period of rare and occasional exploring voyages). The duration of Ceno-

zoic time may be assumed at three million years (Walcott’s estimate).

3) Living mammals have been occasionally observed in such records of nat-

ural rafts. Assume the chance of their occurrence (much greater than of their

presence being noticed) at one in a hundred.

4) Three hundred miles drift would readily reach any of the larger oceanic

islands except New Zealand. Assume as one in ten the probability that the

raft drifted in such a direction as to reach dry land within three hundred

miles.

5) In case such animals reached the island shores and the environment

afforded them a favorable opening, the propagation of the race would require

either two individuals of different sex or a gravid female. Assume the proba-

bility of any of the passengers surviving the dangers of landing as one in

three (by being drawn in at the mouth of some tidal river or protected inlet),

of landing at a point where ‘the environment was sufliciently favorable as

one in ten, the chances of two individuals of different sexes being together

ss A recent number of the Popular Science Monthly (Sept., 1911, vol. lxxix, pp. 303-307)

gives the recorded observations of the drift of a natural raft of. this sort, covering over

a thousand miles of travel.

MATTHEW, CLIMATE AND EVOLUTION 207

might be assumed as one in ten, the alternate of a gravid female as one in

five. The chance of one of the two happening would be 1/10 + 1/5=3/10.

The chance of the species obtaining a foothold would then be 3/10 « 1/5 x

1/10 — one in a hundred.

If then we allow that ten such cases of natural rafts far out at sea have

been reported, we may concede that 1000 have probably occurred in three

centuries and 30,000,000 during the Cenozoic. Of these rafts, only

3,000,000 will have had living mammals*® upon them, of these only 30,000

will have reached land, and in only 300 of these cases will the species have

established a foothold. This is quite sufficient to cover the dozen or two

cases of Mammalia on the larger oceanic islands.

Few of these assumptions can be statistically verified. Yet I think

that, on the whole, they do not overstate the probabilities in each case.

They are intended only as a rough index of the degree of probability that

attaches to the method, and to show that the populating of the oceanic

islands through over-sea transportation, especially upon natural rafts, is

not an explanation to be set aside as too unlikely for consideration.

I have considered the case only in relation to small mammals. With

reptiles and invertebrates, the probabilities in the case vary widely in

different groups, but in almost every instance they would be consider-

ably greater than with mammals. The chance of transportation and sur-

vival would be larger and the geologic time limit in many instances much

longer. Wind, birds, small floating drift and other methods of acci-

dental transportation may have played a more important part with in-

vertebrates, although they cannot be invoked to account for the distribu-

tion of vertebrates. The much larger variety and wider distribution of

infra-mammalian life in oceanic islands is thus quite to be expected. And

the extent and limits of such distribution are in obviously direct accord

with the opportunities for over-sea transportation in different groups.

On the other hand, the transportation of very large animals in this way

may fairly be regarded as a physical impossibility, which could not be

multiplied into a probability by any duration of time. The only methods

of accounting for such animals would be by evolution in loco from small

ancestors, by swimming, by introduction through the agency of man and

by actual continental union.

The first hypothesis would involve evolution in an isolated and more

or less altered environment and would result in wide structural differ-

ences from any continental relatives. The second applies with greater

probability to large than to small animals, but, except for animals of

* Small reptiles and invertebrates would only rarely be observed, if present.

208 ANNALS NEW YORK ACADEMY OF SCIENCES

more or less aquatic habits and within certain limits of distance, it is an

apparent physical impossibility. The third may be either intentional or

accidental and should be considered in connection with the known custom

among Malays and other races, of taming various captured animals and

taking them along on sea-voyages. Its application is, of course, limited

to distributional anomalies of late Pleistocene or modern origin. The

last hypothesis, where it traverses the doctrine of the permanence of ocean

basins, appears to me unnecessary, as I have failed to find a single im-

stance of distribution which cannot reasonably be otherwise explained.

CONSIDERATIONS AFFECTING PROBABILITIES OF OVER-SEA MIGRATION IN

SPECIAL CASES

The probabilities of over-sea transportation to an oceanic island will

obviously be much greater if the island is large, and correspondingly re-

duced if it be of small size. The distance from the mainland will greatly

reduce the chances of such rafts making a landing, for two reasons: first,

the chances of survival of the animals are reduced proportionately to the

length of their journey (or rather, in a varying relation, which for con-

venience we may consider as a direct proportion) ; second, most rafts will

be carried out from one or more points along the coast, but not from all

points equally (that is to say, from the mouths of one or more great

rivers, where the conditions are favorable, seldom from any of the small

rivers). If we disregard prevalent winds and currents and consider the

rafts as drifting out in all directions the probability of their landing on a

given island will be directly proportioned to its length opposite the main-

land, inversely to the distance. The probabilities of survival of animals,

so far as it depends on the raft holding together, will also be inversely as

the number of days exposure to the sea, hence as the distance. Compar-

ing Saint Helena, 1100 miles from Africa and 10 miles diameter, with

Madagascar, 200 miles from Africa and 1000 miles in length, we see that

the probabilities of effecting a colonization would be 100 K 314 X 514,

or 3025 times greater in the case of Madagascar. New Zealand, 800 miles

long and 1200 miles from the Australian coast, will receive 8/10 & 1/6

< 1/6, or 1/45 as many colonizations as Madagascar, but 80 11/12

x 11/12 or 67 times as many as Saint Helena.

I beheve that it is to their small size rather than to unfavorable con-

ditions for survival that the poverty of fauna, especially of higher verte-

brates, in the smaller oceanic islands is due.

The oceanic currents and prevalent winds do, of course, profoundly

modify the above generalities in each individual instance. They have

MATTHEW, CLIMATE AND EVOLUTION 209

prevented the populating of Cuba from North America, while facilitating

invasions from South and Central America. The present set of currents

reduces the probability of mammals reaching Madagascar from the Afri-

can mainland, while increasing the chances of Oriental animals reaching

it. It reduces materially the opportunities for Australian fauna to reach

New Zealand.

We have no adequate data on which to base theories as to the former

set of oceanic currents. A worldwide uniformity of climate would prob-

ably reduce the north and south movement of the waters; the east and

west element of their motions is conditioned by the rotation of the earth,

and its velocity would be reduced proportionately to the north and south

movements; so that a more uniform climate would bring about a reduc-

tion of velocity rather than change in direction. The third principal

conditioning element is the conformation of the continents, and doubtless

the flooding of great areas and the opening up of broad though shallow

passageways between seas now separated would profoundly modify the

surface currents in many regions. The opening of a broad passage be-

tween North and South America would allow the Caribbean current to

pass into the Pacific instead of being deflected northward and eastward

along the shores of the Gulf of Mexico to find an outlet between Cuba

and Florida. The absence of this initial part of the Gulf Stream would

obviously be unfavorable to North or Central American animals reaching

western Cuba. The great equatorial current would sweep across from

Africa along the northern coast of South America, and uninterruptedly

into the Pacific; transportation from Africa to South America or from

South or Central America to the Galapagos Isiands would thus be facili-

tated.

DISPERSAL OF MAMMALIA

MANKIND

We may with advantage begin our review of the special evidence in

support of our theory with the migration history of man. This is the

most recent great migration; it has profoundly affected zodgeographic

conditions; it is the one where our data are most complete and accurate ;

we can perceive its causes and conditions most clearly, and we have a

great deal of corroborative evidence in history and tradition.

All authorities are to-day agreed in placing the center of dispersal of

the human race in Asia. Its more exact location may be differently in-

terpreted, but the consensus of modern opinion would place it probably

in or about the great plateau of central Asia. In this region, now barren

210 ANNALS NEW YORK ACADEMY OF SCIENCES

and sparsely inhabited, are the remains of civilizations perhaps more

ancient than any of which we have record. Immediately around its bor-

ders lie the regions of the earliest recorded civilizations,—of Chaldea, Asia

Minor and Egypt to the westward, of India to the south, of China to the

east. From this region came the successive invasions which overflowed

Europe in prehistoric, classical and medixval times, each tribe pressing

on the borders of those beyond it and in its turn being pressed on from

Fic. 6.—Dispersal and distribution of the principal races of man

No attempt is made to indicate anything beyond the broader lines of dispersal.

behind. The whole history of India is similar,—of successive invasions

pouring down from the north. In the Chinese Empire, the invasions

come from the west. In North America, the course of migration was

from Alaska, spreading fan-wise to the south and southeast and continu-

ing down along the flanks of the Cordilleras to the farthest extremity of

South America. Owing to the facilities for southward migration af-

forded by the great Cordilleran ranges, the most remote parts of the New

World are the forests of Brazil and of northeast South America. In the

northern continent, Florida is the most distant from the source of mi-

gration.

MATTHEW, CLIMATE AND EVOLUTION D111

In Africa, the region north of the Sahara has been overrun by succes-

sively higher types from the east. The great desert was a barrier to

southward migration, being pierced only by the narrow strip of the Nile

valley, from whose head spread out the successive populations of central

and southern Africa. The main trend of migration followed the eastern

highlands, the valleys of the Niger and Congo being more remote.

In the East Indies, the succession of great islands to the southeast,

perhaps more connected formerly than now, formed stepping stones of

migration to the distant continent of Australia.

The lowest and most primitive races of men are to be found in Aus-

tralasia, in the remoter districts of southern India and Ceylon, in the

Andaman Islands, in southwest and west central Africa and, as far as the

New World is concerned, in northern Brazil. These are the regions most

remote, so far as practicable travel-routes are concerned, from Central

Asia. A century ago, the present habitat of primitive races was taken to

be approximately the primeval home of man. With our present under-

standing of the conditions and causes of migration, a theory more in ac-

cord with tradition and history is generally accepted, and the dispersal

center of man is regarded as situated in central or southern Asia. The

influence of the old opinion is perhaps seen in the tendency to place this

region south of the great Himalayan ridge and in tropical or semi-trop-

ical climate.

This last assumption—that man is primarily adapted to a tropical cli-

mate—is, I think, only partly true at best. Its general acceptance is

perhaps due, among other reasons, to the supposed relation between loss

of hair on the body and the wearing of clothes, the first being regarded as

an earlier specialization in an environment of tropical forests, the second

as a secondary adaptation resulting from migration to a cold climate.

But here, it seems to me, we are putting the cart before the horse. We

may more reasonably regard the loss of hair in the human species as a

result of wearing clothes and conditioned by this habit, rather than attrib-

ute it to any climatic conditions. This view is supported by several points

in which the loss of hair in man is differentiated from the partial or com-

plete loss of hair common in tropical animals, the following two being

most clearly significant.

1) It is accompanied by an exceptional and progressive delicacy of skin,

quite unsuited to travel in tropical forests. I do not know of any thin-haired

or hairless tropical animal whose skin is not more or less thickened for pro-

tection against chafing, the attacks of insects, ete.

2) The loss is most complete on the back and abdomen. The arms and the

legs and, in the male, the chest, retain hair much more persistently. This is

212 ANNALS NEW YORK ACADEMY OF SCIENCES

just what would naturally happen if the loss of hair were due tu the wearing

of clothes,—at first and for a long time, a skin thrown over the shoulders and

tied around the waist. But if the loss of hair were conditioned by climate it

should, as it invariably does among animals, disappear first on the under side

of the body and the limbs and be retained longest on the back and shoulders.

It will not be questioned that the higher races of man are adapted to

a cool-temperate climate, and to an environment rather of open grassy

plains than of dense moist forests. In such conditions they reach their

highest physical, mental and social attainments. In the tropical and

especially in the moist tropical environment, the physique is poor, the

death rate is high, it is difficult to work vigorously or continuously, and

especial and unusual precautions are necessary for protection from dis-

eases and enemies against which no natural immunity exists and which

are absent from the colder and drier environment.

This lack of adaptation to tropical climate is also true, although to a

less degree, of the lower races of man. Aithough from prolonged resi-

dence in tropical climate they have acquired a partial immunity from the

environment so unfavorable to the newcomer, yet it is by no means com-

plete. The most thoroughly acclimatized race—the negro—reaches his

highest physical development not in the great equatorial forests but in the

drier and cooler highlands of eastern Africa; and when transported to

the temperate United States, the West Coast negro yet finds the environ-

ment a more favorable one than that to which his ancestors have been

endeavoring for thousands of years to accustom themselves. In tropical

South America, the Indians, as Bates long ago remarked, seem very im-

perfectly acclimatized and suffer severely from the hot moist weather ;

much more than the negroes, whose adaptation to tropical climate has

been a much longer one. :

In view of the data obtainable from historical record, from tradition,

from the present geographical distribution of higher and lower races ot

men, from the physical and physiological adaptation of all and especially

of the higher races, it seems fair to conclude that the center of dispersal

of mankind in prehistoric times was central Asia north of the great Hima-

layan ranges, and that when by progressive aridity that region became

desert it was transferred to the regions bordering it to the east, south and

west. We may further assume that the environment in which man pri-

marily evolved was not a moist or tropical climate, but a temperate and

more or less arid one, progressively cold and dry during the course of his

evolution. In this region and under these conditions, the race first at-

tained a dominance which enabled it to spread out in successive waves of

MATTHEW, CLIMATE AND EVOLUTION 91:

migration to the most remote parts of the earth. The great mountain

ranges to the south impeded migration in this direction, while to east and

northeast, west and northwest, migration was easy and rapid. Reaching

the New World by way of the Alaskan bridge, the long uninterrupted

chain of the Cordilleras facilitated migration along their flanks to the

farthest limits of South America.

There is little evidence if any, in the New World, of any migrations of

inferior races long preceding those of the Amerind tribes, which would

seem to have branched off at a moderately high stage in the evolution of

mankind. Per contra, we find in South Africa, in Australia, in penin-

sular India and elsewhere, remnants of what must have been an early

cycle of migrations. Each group of this early cycle, derived primarily

from a different part of the central region of dispersal, has specialized

further in proportion to its isolation and yet retains a predominance of

the common primitive characters representing the stage of development

attained when it left the dispersal center. The populating of Africa by

the negroes may be regarded as the latest phase of this early cycle of dis-

persal, or should perhaps be considered independently.

The later development of the race is conditioned by its splitting in the

region of dispersal into an eastern or Mongolian and a western or Cau-

easian stock. This split was presumably conditioned by the east-west

elongation of the dispersal center caused by the facility of expansion in

these directions and the mountain barriers to the south. All the east-

ward migrations from this time on bear a distinctly Mongolian stamp.

An early phase of this stage is represented by the population of the New

World and the variously mixed Malayan peoples. A later phase appears

in the more typical Mongolian races. All the westward migrations, on

the other hand, are of Caucasian affinities, this stock splitting, as the re-

gion of favorable environment widened out westward, into northeastern

or Nordic, southwestern or Mediterranean groups. The peoples of north-

ern Europe are derived from the successive migration waves of the first,

those of southern Europe and northeast Africa from the second; the in-

termediate Alpine stock of central Europe is considered to represent a

somewhat older migration allied to the Slavic peoples, who are to-day

the principal population of eastern Europe, the latest cycle of Caucasian

dispersal.

I have gone into this brief recital of the migration and dispersal his-

tory of mankind, not to present anything novel or authoritative, but be-

cause we have more evidence, direct and indirect, and more insight into

the conditions and causes which controlled its course, than with any other

214 ANNALS NEW YORK ACADEMY OF SCIENCES

race of mammals. I believe that these controlling causes have been sub-

stantially the same in the lower animals as in man and their methods

and routes of dispersal largely identical.*°

PRIMATES

We have seen that the dispersal center of man is in central Asia; that,

in the present distribution, the survivors of the earliest cycle are found

DISTRIBUTION OF PRIMATES

== Movern AntTHRopoiDed (MONKEYS, APES , BABOONS )

Wu ” LemuroipEa (LEMURS ,LORIS, TARSIER)

E, Eocene (Ano OligoceneyL EMUROIDS

0, Oricocene ANTHROPOIDS

M, Miocene y

P, Puiocene os)

ore

uth

til

oo”

™

Fic. 7.—Dispersal of the Primates

The marginal position of the modern lemurs, the progressive disappearance of the order

from the more central regions which it formerly inhabited are clearly shown.

in Africa, peninsular India, the East Indies and Australia; that the

populating of the New World belongs to a later cycle of distribution,

and we have no good evidence that the earlier cycle ever reached it; that

the dominant migration in the Old World has been east and west, prog-

ress to the south being hindered by the transverse mountain system to

the south of which more primitive types long survived, while in the New

World the dominant line of migration has been to the southward from

Alaska, and eastward migration has been slower.

40 One notes, too, the same fallacy in interpreting the data; some authors are disposed

to place the center of dispersal of European races or languages in western Europe or in

northern Africa because they find there the most primitive surviving races or languages.

MATTHEW, CLIMATE AND EVOLUTION 915

In the hving Primates we have survivors of pre-human stages in the

evolution of man, specialized to a varying extent in different directions

from him, so that they have not come into direct rivalry with him, and

have hence survived.

The latest infra-human cycle is represented by the anthropoid apes,

surviving to-day in the forests of West Africa and of the East Indies.

We may suppose that these are remnants of a cycle of dispersal from a

central Asiatic source, but we have no sufficient data to define its extent

or time, except as late Tertiary and probably limited to Arctogea.

Nearest to man in intelligence and habits, this cycle has been swept out

of existence, except for the few members which were or became adapted,

LIVING AND EXTINCT GROUPS OF PRIMATES

LEMUROIDEA ANTHROPOIDEA

NSECT-

IVORA

Progressive EVOLUTION oF

THE HIGHER Groups oF PRIMATES

DURING THE TERTIARY PERIOD

Fic. 8.—Phylogenetic relations of the living and extinct groups of Primates

The circles indicate the size and known geological range of the several groups, the

dotted lines their most probable derivation. Their supposed relations to certain Insectiy-

ora and intermediate extinct groups are also indicated.

as our own ancestors were not, to tropical forest hfe. The arboreal

habitat may be interpreted as a partial reversion. The doubtful and

fragmentary remains of anthropoid apes in the Pliocene of Europe and

of northern India are about all that the geological record has to state in

regard to the former distribution of this cycle.

The next lower cycle is that of the monkeys and baboons of the Old

World, and as a very doubtful early phase, the New World monkeys.

The Old World monkeys inhabit most of Africa, India and the East

Indies. To the northeast they extend to southern Japan. Closely re-

lated forms are found in the late Miocene of central and southern Eu-

216 ANNALS NEW YORK ACADEMY OF SCIENCES

rope, in the Pliocene. of India, in the so-called Pliocene (which may be

Miocene) of China. These may all be referred to a central Asiatic

source. The dispersal of this cycle must date back at least to the be-

ginning of the Oligocene, for it had reached as far as Egypt at the date

of the Faytim fauna as shown by Schlosser’s recent discoveries.** With

the New World monkeys, the evidence seems rather to point to inde-

pendent evolution in South America from éarly Tertiary Primates of an

Eocene cycle of dispersal. For no remains of Primates have been dis-

covered in any Oligocene or later formation in the United States, while

the later Tertiary formations of the Argentine have yielded remains of

a number of Primates apparently intermediate between Eocene lemurs

~and South American monkeys.

The oldest cycle of primate dispersal is that represented by the lemurs.

These are now most abundant in Madagascar; a few exist in west and

central Africa, peninsular India and the East Indies. Lemuroid pri-

mates, lacking certain specialized characters of modern lemurs but other-

wise closely related, and equivalent in stage of development, are found

abundantly in the Eocene of Europe and the United States. They are

very doubtfully represented in the early Tertiary formations of the

Argentine. We know too little of the Tertiary of other parts of the

world to make any inference as to the extent of their distribution at

that time, or the course of its subsequent changes. They disappear in

Europe and North America at the end of the Eocene; in South America,

they may have evolved into New World monkeys, while in the Old World

they must have given rise to the higher primates. It is reasonably cer-

tain that the theater of their evolution was not Europe, and although

they are not known in the Oligocene Faytim fauna of Egypt, we may

doubtfully suppose that they had reached that continent at some time

during the Eocene. Madagascar most probably received its lemurs from

Africa, but it is reasonable to suppose that only a single type, allied to

the Eocene Adapide, reached the island, and in the favorable environ-

ment radiated out into a number of diverse adaptations taking the place

of various mammal groups not present in the island fauna.

From the fact that the European and North American lemurs are in

an equivalent stage of development, although not very closely related,

we may fairly infer that they were derived very early in the Tertiary

from an intermediate center of dispersal, presumably Asia north of the

Himalayas.

41 Max ScHLOSSER: “Beitriige zur Kenntniss der Oligoziinen Landsiiugethieren aus dem

Fayum Aegypten,”’ Beit. zur Pal. u. Geol. Oest-Ung., B’d xxiv, s. 52. 1912.

MATTHEW, CLIMATE AND HVOLUTION 917

CARNIVORA

The modern land Carnivora are spread over all the great continents

except Australia, where a single species of wild dog, probably introduced

by man, is their only representative. They are found equally in all the

continental islands (7. e., those included within the continental shelf

border), and a few have reached Madagascar and other large oceanic

islands.

Miocene relatives of

Cyon, Lelicyon Ly caon &

Dingey nope =

Dinocynops

(Pleislocen e)

Ce dingo,

/ probably intro

: ‘diseeld in latel§

Pleislocene

Eocene lo Recent =

Fic. 9.—Distribution of the modern Canide

The jackals (Ethiopian and Oriental) are slightly more primitive than the true wolves

and foxes; the Neotropical ‘Dog-foxes’’ more distinctly so. Cyon, Icticyon and Lycaon

appear to be dispersed remnants of an aberrant group formerly Holarctic; the ancestry

of the more typical Canidz is also found in Holaretica.

The order is unquestionably of Holarctic origin. Primitive Carnivora

(Creodonta) are abundant in all the earlier Tertiary formations of Eu-

rope and North America, one group (Miacidw) ancestral to the higher

Carnivora (Fissipedia), others which became extinct during the Oligo-

cene. True fissipede Carnivora first appear in the Upper Kocene in

Europe and North America and differentiate into the diverse modern

types through the remainder of the Tertiary. They did not reach South

218 ANNALS NEW YORK ACADEMY OF SCIENCES

America until the Pliocene, their place being supplied up to that time

by carnivorous marsupials. In Australia, their place is still taken by

carnivorous marsupials. In Africa, primitive Carnivora (creodonta)

appear in the Oligocene, represented only by the extinct family of hyaeno-

donts, all of them derivable from Eocene hyznodonts of the Holarctic

region; but the contemporary Holarctic Fissipedia had not yet reached

Africa. ,

The modern Jand Carnivora are divided into seven families, each rep-

resenting one or more broad phyla. ‘The various divergent adaptations

of the phyla and secondary re-adaptations of subphyla have brought

about an amount of convergence and parallelism which makes it difficult

to disentangle or to state accurately the true genetic relationship in any

terms of classification. Some of the phyla are Holarctic, others Pale-

arctic or Nearctic. In all of them, we find the most primitive modern

survivors in the tropical regions, the most advanced types in the Holarctic.

Canide.—The Canidex are the most cosmopolitan family of the order.

It is also the most progressive family in its adaptation to the open plains

and arid climate of the great modern continents. The gradual adapta-

tion of the race to these conditions from primitive arboreal forest-living

ancestors can be traced through successive stages in the Tertiary forma-

tions of Europe and North America, but most completely in the latter

country. The lengthening of the limbs and their adaptation for swift

running, the reduction of the long balancing tail to a short comparatively

unimportant organ, the perfection of the shearing and crushing teeth

and, especially, the steady increase of brain capacity are the chief lines

of progress. While most of the surviving Canide conform pretty closely

to a single type, we find a tendency among their Tertiary ancestors to

branch off on the one hand into more predaceous, on the other into more

omnivorous types. Most of these have disappeared, but in the Oriental

Ethiopian and Neotropical regions we find in the genera Cyon, Icticyon

~ and Lycaon survivors of a more predaceous group which is known from

the Oligocene and Miocene of the Holarctic region. This group has

disappeared from Holarctica by the end of the Tertiary; two or three

representatives are found in the Pleistocene of South America. Among

the more typical modern dogs, the wolves and foxes are the most pro-

gressive types, the jackals slightly less so, the African fennec retains

most nearly the primitive long tail, the South African Otocyon, while

anomalous in possessing an extra molar tooth, is likewise normally primi-

tive in several characters and the Neotropical “dog-foxes” show a marked

resemblance in many details to the late Tertiary Canide of North Amer-

ica. The fact that the Canide are preéminently adapted to open country

MATTHEW, CLIMATE AND EVOLUTION 219

and more or less arid climate is of primary importance in explaining

their present dominance and cosmopolitanism, their close association with

man, their absence from Madagascar and other oceanic islands; and it

makes it most probable that the introduction of the dingo to Australia

was through human agency although undoubtedly as early as the late

Pleistocene. In their adaptation and distribution this family of Car-

nivora largely parallels the Equide among Perissodactyla.

TABLE I1.—Distribution of the Canide

Neotropical Holarctic | Ethiopian Oriental | Australian

. Canis AA

Canis ae Canis Cues

Recent Teticyon Canis Cae Cyon Canis

Canis ‘,

Pleistocene | Icticyon Canis Canis als Canis

Dinocynops Y

. ; Canis (Record in- | Canis

Pliocene (?) Amphicyon Ga: ete. | * de quate) | Vulpes (No record)

Tephrocyon

Miocene None ae Nae yonine No record | Amphicyon | (No record)

Cyon, ete.

Cephalogale

: ‘ Cynodictis a2 Amphicyon

Oligocene None Daphznus, ete. None Cephalogale (No record)

‘‘Amphicyon’’

Cynodictis, ete.

Eocene None Cynoid (No record)

Miacidee

42Fayfm fauna, Egypt. Although this locality is not to-day within the Ethiopian

province, its fossil mammals are generally regarded as representing the Hthiopian and

not the Mediterranean fauna of the Oligocene. My own impression with regard to it is

that it is transitional, as the Egyptian fauna is to-day, but dominantly Ethiopian instead

of dominantly Mediterranean.

220 ANNALS NEW YORK ACADEMY OF SCIENCES

Procyonide.—The family Procyonide includes a member of omnivor-

ous specializations from the central phylum now represented by the

Canide. All of them are arboreal, partly retaining and partly reverting

to the primitive mode of life in this respect. They are mainly Neotrop-

“

WH, Procyonidde wee Procyon =

NT 7 EN Neae Ter liarpanceslops =:

, =~

of Viverrdé

No Procyonidae fs

unl Pliocene

Fic. 10.—Distribution of the Procyonide and Viverrida, formerly Nearctic and

Palearctic, but now surviving chiefly in the peripheral regions

The geographical position of Aelurws is anomalous for a member of the Procyonide, to

which family it is usually referred. Its true affinities, however, are doubtful.

ical, but the raccoon, the most dog-like of the family, survives as far

north as the Sonoran region. The panda of the Himalayas is usually

placed with Procyonide, but its true affinity is not very clear.

MATTHEW, CLIMATE AND EVOLUTION

TABLE III.—Distribution of the Procyonide

221

Holarctic

Neotropical =

Sonoran Palearctic

Procyon

Nasua Alurus

Recent Cercoleptes Procyon (Affinities question-

Bassaricyon able)

Bassariscus

Pleistocene (Not recorded) Procyon

Amphinasua Parailurus

Pliocene Pachynasua Probassariscus (Affinities question-

Cyonasua able)

; Leptarctus

Miocene None Phiaocyon

C | dicti.

Hae ynodictis —

Oligocene NORE (Probably ancestral in part)

Eocene — None Miacidee

Mustelide.—Primarily the Mustelide represent a more predaceous

adaptation than the Canide. Their development through the Tertiary

in the Holarctic region can be traced almost as completely as that of

the dogs. Like the Canide (though not as early), they perfected during

the later Tertiary a differentiation of the back teeth into shearing and

crushing types, and they are equally progressive in brain development

but much less so in running powers, retaining to a great extent their

primitive forest-living habitat. They are to-day chiefly holarctic, the

most progressive typical mustelids being the martens, weasels, ferrets

and wolverenes. Karly in the Tertiary there appear divergent side

branches, specialized descendants of which survive to-day in the badgers,

skunks and otters of the northern world, the intermediate forms being

now extinct or confined to India and Africa.

Urside.—The bears are regarded by many paleontologists as an off-

shoot from the Canide, but, on structural evidence, they appear to be

related rather to the Mustelidew. Their distribution indicates derivation

299 ANNALS NEW YORK ACADEMY OF SCIENCES

from a Palearctic source. The most primitive bears first appear in the

Miocene of Europe; in the New World, they first appear in the Pleisto-

cene. They are to-day chiefly Holarctic; the single South American

species is distinctly primitive; the Oriental sun-bear and sloth-bear are

partly aberrant, partly primitive. The Thibetan 2/uropus is aberrant

and specialized ; its relation to the typical Wrsid@ is not very close.

Vwerride.—The Viverride are now almost exclusively Oriental and

Kthiopian and have conserved the primitive type more than any other

——_

No Ur sidae

unt) Pleislocene

1 = a 7r

Vy Se Ancestry

D Lae == Of Ursidae

fe =" tn later

Tertiary

Fig. 11.—Distribution of the Urside, Pleistocene and Recent

The group appears to have dispersed from a Palearctic center, its Tertiary ancestral

series being found in Europe and in the Pliocene of India and China.

Carnivora, except some of the Procyonide which have a somewhat corre-

sponding geographic position in the New World. The three most pro-

gessive genera, /erpestes, Genetta and Viverra, survive to-day along the

southern borders of the Palearctic region; the remainder are Ethiopian

or Oriental, the most primitive living genera being west African and

East Indian. Herpestes and Viverra occur in the Oligocene and Mio-

cene of Germany and France, and more primitive extinct genera in the

Upper Eocene of Europe.

MATTHEW, CLIMATE AND EVOLUTION 993

The primitive character of the viverrines is especially seen in their

imperfect differentiation of shearing and crushing back teeth, their

rather short limbs, long bodies, long tails and relatively small brain

capacity.

Hyenide.—tThe family Hyenide is generally regarded as a specialized

offshoot from the Viverride and is apparently connected with the Kuro-

pean Miocene viverrids by a series of intermediate forms. The latest

development of the race, the genus Hyena, inhabited Europe and Cen-

tral Asia and China in the Pliocene and Pleistocene but is now found

only in India, Africa and southwestern Asia.

Felida.—The Felide are almost as cosmopolitan as the dogs and are

even more uniform in type, the cheetah being the only marked living

variant. A notably different specialization is shown in the extinet

macherodonts or sabre-tooth tigers, and in the Tertiary sequence in

Europe and America we find approximate genetic series, parallel in the

two countries, by which the true cats and macherodonts converge towards

a common primitive type, in which the upper canines are moderately

elongated. According to this phylogeny, the clouded tiger of Sumatra

and Java is the most primitive living felid, while the double series in

Europe on one hand and North America on the other, would indicate

northern Asia as the center of dispersal of the race. The range of some

of the modern species is very great. The puma extends in the New

World from Alaska to Patagonia, the tiger in the Old World from Man-

churia to Java. We may note, however, that the tiger is regarded by

Blanford as a recent immigrant into southern India; while, on the other

hand, it is known that the northern range of the lion has been pro-

gressively restricted during prehistoric and historic times from northern

Europe to its present limits of southwestern Asia and Africa.

PINNIPEDIA

When dealing with littoral and marine mammals we must expect to

find the conditions of their evolution somewhat different. If the hypoth-

esis be valid that the progressive refrigeration of the polar regions was

the dominant cause of evolutionary progress and geographic dispersal,

an examination of the map will show that the Arctic-North Atlantic basin

affords the most favorable region. The Arctic basin centers around the

pole, and a broad shelf of shallow water encircles it, extending as far

south as latitude 45°. The North Pacific basin was closed to the north-

ward by the Alaskan land-bridge during a large part if not all of the

Tertiary, and its shores plunge suddenly to great depths, margined by

294. ANNALS NEW YORK ACADEMY OF SCIENCES

high mountains, affording less opportunity for expansional evolution of

the littoral fauna. The Antarctic continent appears equally unfavorable,

and dispersal from that center would also be hindered by the broad

stretches of ocean.

We may expect, therefore, to find the littoral fauna of the North At-

lantic most progressive, that of the North Pacific less so, the tropical

faune containing many relict types of discontinuous distribution, and

the Antarctic faune partly composed of types from the north which had

crossed the barrier of warm water when the climatic zones were less

differentiated than they now are; partly of groups developed in the south.

Whether these groups were closely allied on the different southern con-

tinental shores would depend on their ability to cross the great barriers

of deep ocean that separate them.

The distribution of the pinnipeds accords with these principles. The

most specialized family is the Phocide, originating apparently in the

Atlantic-Arctic basin, where Phoca, the most progressive genus, is found

in the North Atlantic and Arctic seas and has penetrated into the North

Pacific as far as California and Japan. Southward in the Atlantic it is

succeeded by the less progressive Monachus in the Mediterranean and

Antillean region. The Antarctic Phocide are also primitive and archaic,

related more or less nearly to Monachus. In the Pliocene of Belgium

are found extinct genera closely related to Phoca and others more primi-

tive allied to Monachus.

The walruses, also Arctic and North Atlantic, have penetrated into

the North Pacific only as far as Bering Sea; they are likewise recorded

from the Pliocene of Northern Europe and along the North Atlantic in

the Pleistocene as far south as Virginia.

The third family, the Otariidz, is decidedly more primitive in struc-

ture, being less specialized for marine life. They are found in all the

southern seas and on the North Pacific coasts. They are unknown to

the North Atlantic and Arctic shores and have never been found fossil

in either Europe or eastern North America. Desmatophoca and Ponto-

leon of the Miocene of Oregon are perhaps ancestral types, but more

evidence is necessary before its North Pacific origin can be regarded as

satisfactorily indicated.

INSECTIVORA

Among the Insectivora we deal with a number of very ancient races,

whose relationship is much more distant than in many other mammalian

orders. They are small, and most of the surviving members are scarce

and little known, while they are still less known as fossils. So far as

MATTHEW, CLIMATE AND EVOLUTION 225

we have any satisfactory evidence, the different races or most of them

appear to have originated in the Holarctic region and spread to the

southward. ‘The most primitive division, the zalambdodonta, includes

four families, the Centetide of Madagascar, Chrysochloride of South

Africa, Potamogalide of West Africa and Solenodontidz of Cuba. Fossil

zalambdodonts are found in the late Miocene in South America, in the

early Oligocene (and recently in the Basal Eocene) in North America.

These indications are in conformity with the derivation of the group

Soricidae and

Talpidde since

Oligocene

Fic. 12.—Distribution of Soricide (right to left shading) and of Talpide (left to right

shading)

The less specialized Soricide are more widely dispersed, the highly specialized Talpide

limited to Holarctica. Ancestral types of both are found in the Tertiary of Europe and

North America, but the evidence as to their phylogeny is very scanty.

from very ancient Holarctic ancestors, the modern zalambdodonts being

the last surviving remnants of a dispersal from the north in early Ter-

tiary or possibly pre-Tertiary times. But the evidence is too slight to

be conclusive.

The hedgehogs are more clearly of Palearctic origin, the most primi-

tive survivors being the East Indian Gymnura and Hylomys, while the

most progressive genus, Hrinaceus, is Palearctic and is preceded in the

226 ANNALS NEW YORK ACADEMY OF SCIENCES

Oligocene aud Miocene of Europe by more primitive ancestral forms. A

relatively primitive genus, Proterix, occurs in the Oligocene of South

Dakota, as a contemporary with more progressive genera in the Oligocene

of Europe. The family is otherwise unknown in the New World.

The moles and shrews are also evidently of northern origin. Of the

two families, the Soricide are more primitive in structure and have

spread more widely; the more specialized Talpide are still limited to

Holarctica, and in the extreme north their exclusion from the areas of

permanently frozen subsoil has split their range into two disconnected

areas. The most progressive and abundant shrews are Holarctic, while

the Oriental and African species (Crocidurine) retain some primitive

characters. Fossil moles and shrews in the middle Tertiary of Europe

and America indicate that the divergence between the two families was

not then so great as now. ‘The modern genera are reported to occur

(but on inadequate evidence) as early as the Miocene in Europe and

America. Jaws of several minute talpoid genera are known from the

Middle and Lower Eocene of North America. They are unknown in the

extra-Holarctic Tertiary, but this negative evidence is of no weight in

view of their minute size and rarity.

The Tupaiide of the East Indies and Macroscelidide of Africa occupy

a somewhat anomalous position, since they are of higher type in brain

development than other Insectivora and in many respects are nearer to

the higher placental mammals.** Their distribution so remote from the

great northern dispersal center may perhaps best be accounted for by

considering the fact that their specializations, adaptations and habits of

life are of a less unusual kind than in most of the lower insectivores and

would bring them more directly into rivalry with certain groups of

rodents, with which they were unable to contend successfully and were

compelled to retreat southward in consequence. No fossil remains cer-

tainly referable to these families are known, although quite a number

of early Tertiary genera of Europe and North America have been or

might be provisionally referred to them.**

There are a large number of primitive Insectivora in the Eocene of

North America and a few in Europe, which do not seem to be nearly

ancestral to any modern group but rather indicate that the order once

#8 This anomaly in distribution is now removed by the studies of Gregory and Elliott

Smith, which show that the true relations of Tupaia and presumably of Macroscelides,

are with the Primates, rather than with the Insectivora. Their geographic distribution

is quite normal on this view of their affinities.

44 Hntomolestes of the Middle Eocene of North America is regarded by Dr. Gregory as

probably related to Tupaia, and a number of other small mammals from the Bridger and

Wasatch may be related to this group of Insectivora.

MATTHEW, CLIMATE AND EVOLUTION 997

took a much more important place in the mammalian faune of the world

than it does now. This should be kept in mind in considering the rela-

tions of the Insectivora.

CHIROPTERA

I am not sufficiently acquainted with modern Chiroptera to venture

an opinion as to whether or not their geographical distribution indicates

their place of origin, but I should not expect to find much satisfactory

evidence, as they are known to be of very ancient specialization and to

have greater facilities for wide distribution than terrestrial animals.

Dr. Andersen,*® in his recent Catalogue of the Chiroptera in the

British Museum, remarks: “The evidence afforded by the geographical

distribution of Bats has generally been considered of doubtful value;

hence they have either been entirely excluded from the material worked

out by zodgeographers, or at least treated with pronounced suspicion as

likely to be more or less unreliable documents of evidence. This un-

willingness or hesitation to place Bats on an equal zodgeographic footing

with non-flying Mammalia would seem to be due partly to the precon-

ceived idea that owing to their power of flight Bats must evidently have

been able easily to spread across barriers which in ordinary circumstances

are insuperable for wingless Mammalia; partly to the fact that hitherto

very often whole series of distinct forms have been concealed under one

technical name. . . .” [the author cites a series of instances of this

kind which] “tend to show that the present distribution of the Mega-

chiroptera has not been influenced to any great, and as a rule not to

any appreciable extent by their power of flight; if it had the Fruit-bat

fauna of islands could not so commonly as is actually the case differ

from that of a neighoring group or continent, and the tendency to dif-

ferentiation of insular species or forms would have been neutralized by

the free intercourse between neighboring faunas.”

The belief that bats are more easily able to cross ocean barriers than

non-flying mammals is probably based, not on the preconceived idea that

they could, but upon the plain fact that they have done so far more

frequently. Birds and bats are found upon numerous oceanic islands

where no non-flying mammals, and very few non-flying animals at all,

exist. That they have wings and occasionally use them for so long a

journey, whether voluntarily or involuntarily, is a natural explanation.

I cannot see any other reasonable interpretation of the fact that they

are present and the terrestrial mammals absent in so many remote oceanic

4K. ANDERSEN: Catalogue of the Chiroptera in the British Museum, Vol. I, Megachi-

roptera, p. lxxvi. 1912.

yore} ANNALS NEW YORK ACADEMY OF SCIENCES

islands. With bats, as with most birds, the intervening ocean acts as a

hindrance, but their wider distribution shows that it is less of a hindrance

than with terrestrial mammals.

RODENTIA

The abundant and dominant order of: Rodentia lends, in general,

strong support to the theories here advocated; but there are certain

serious difficulties which can be reconciled only by appealing to the im-

perfection of the geological record.

The rabbits and picas form a group apart, the former Nearctic, the

latter Palearctic since the Oligocene, and both Holarctic since the

Pleistocene, the rabbits having extended their range over most of the

Oriental region and a large part of the Ethiopian and Neotropical. A

single specimen is recorded as from the Pleistocene of South America;

their introduction to Australia is known to have been by civilized man.

Of the remaining rodents, the myomorph families are evidently of

Holarctice origin, as they first appear in Europe and North America in

the Oligocene and the highest and most progressive modern types (e. g.,

Arvicoline) are now Holarctic, while in the southern continents they

are unknown until the Pleistocene and various primitive survivals are

found still living in Oriental, Ethiopian and Neotropical regions. We

may note, however, that the very abundant and typical group of Cricetine

has its most primitive living representatives in tropical regions, that as

we go south in South America, the genera approximate more toward the

more specialized arvicoline type, in the same way that they do as we go

northward in the northern continents.*® ‘Since there is no doubt that

the cricetines are of northern origin, appearing first in South America

in the Pliocene or Pleistocene, while they are common in the Holarctie

regions from the Oligocene to the present day, we must suppose that the

higher development of the Antarctic genera, to which Oldfield Thomas

has called attention, is a case of parallelism with that of the Arctic

genera and that the colder climate of the far south is the stimulus which

reversed the usual conditions of geographical distribution. A review of

the fauna of the Argentine as compared with that of tropical South

America tends to show, I think, that this condition is general throughout,

and that the fauna is more progressive and more nearly equivalent in

development to those of the northern world than is that of the intervening

tropical zone. This is equally true of autochthonic races and of those

which are demonstrably of northern origin. Compare distribution of the

46 OLDFIDLD THOMAS,

MATTHEW, CLIMATE AND EVOLUTION 229

genera of Procyonide, Canidee, Cervide, Tatuide and Dasypodide among

mammals.

Among the sciuromorphs, the squirrels are of early appearance (Oligo-

cene) in the northern world but are now most abundant in the Hast

Indies. The more specialized and later appearing marmots are chiefly

Holarctic. The highly specialized beavers and pocket-gophers are Hol-

arctic and Nearctic respectively, from their first appearance. A marked

exception to the rule is seen in the survival in the western Sonoran sub-

iG : x

Wj Geomyidae Oligocen 10 CORE

NX deteromyidae Anteslors of.

— Pedetidae /Geomyidie ana

Stele: Van

MM Aromadirae eleromylade

{?Anomaluroidea

— ia hnevido os

Fic. 13.—Distribution of Geomyoidea, Anomaluride and Pedetide

The Geomyoidea are of Nearctic origin, but the more primitive Heteromyide have

spread into part of South America. The Anomaluride are thought to be the nearest

living relatives of the early Tertiary Theridomyide. The Pedetide are an aberrant

specialization, derived perhaps from the same group.

region of Aplodontia, the most primitive living sciuromorph in several

respects. I have no explanation to offer of this anomaly, save that we

have not yet balanced properly the essential qualities of progressiveness

among Rodentia.

Among the hystricomorphs, we find serious difficulties in the distribu-

tion. The most primitive living group is certainly the Anomaluride

of West Africa; but, like the Pedetide of South Africa, they offer a

230 ANNALS NEW YORK ACADEMY OF SCIENCES

puzzling admixture of characters, which makes it doubtful whether they

should be reckoned as pertaining to the same stock as the other hystrico-

morphs. The remaining families, while chiefly South American, are

also partly represented in the Ethiopian, Oriental and Holarctic regions.

It may be possible, in view of the facts that the European Theridomyide

antedate geologically any specialized hystricomorphs, are apparently di-

rectly intermediate between the primitive rodent type (Paramys and its

allies) and the hystricomorphs and show the early stages of differentia-

tion of several hystricomorph families, that the Hystricomorpha are a

hes

ami

Lerliary anceslo

No Erelaizontidde oY Hy slricidde

anil

Tertiary ances lors

of Brethizon lidae

Fic. 14.—Distribution of the true porcupines (Hystricide) and New World porcupines

(Frethizontide)

The Hystricide appear to be of Palearctic dispersal, the Erethizontide are apparently

of Neotropical origin.

group of Holarctic origin which has spread into all the southern conti-

nents and specialized independently on parallel lines. But their entire

absence from the recorded North American ‘l'ertiary is then explainable

only by the defective record, and our knowledge of North American Ter-

tiary rodents is so extensive that I should hardly regard this assumption

as justifiable. The fact that the highest and most specialized types are

South American necessarily involves the idea that that continent has

been the most important center of their later development and dispersal,

MATTHEW, CLIMATE AND EVOLUTION 234

and the alliance of the African to the South American genera and of

the New and Old World porcupines must be regarded as more remote

than it appears. Dispersal from South America by help of Antarctic

or transatlantic land-bridges will not solve the problems of their distri-

bution much better. The most specialized porcupines in most respects

are the hystricids of the Old World—late Tertiary in Nurope, now chiefly

Oriental and African. The Nearctic porcupines (rethizon) are more

advanced in several features than the Neotropical (Synetheres). Yet

the ancestors of the New World porcupines at least occur in the late

Tertiary of South America and are absent or unrecorded from the Ter-

tiary of North America. The distribution of the Octodontide in Africa

and South America would possibly admit of being interpreted by parallel

development from theridomyid ancestors; but the parallelism must have

been singularly close, and the absence or non-recognition of Therido-

myide from the North American Tertiaries appears surprising. I have

been unable to frame any hypothesis which will fit all the facts of distri-

bution in this group,*? except by assuming that the South American

Hystricomorpha, which as Scott has shown are all clearly derived from

a single stock, reached South America from Africa in the Oligocene by

over-sea raft transportation. This involves so long a voyage that I hesi-

tate to accept it as a reasonable probability, even though the winds and

currents would obviously favor transportation in this direction.

The Hystricide may fairly be assumed as of Old World origin, and

probably Palearctic, since they are represented in the later Tertiary of

Europe and are unknown in the New World. The Erethizontidz must

apparently be derived from South America, since they are unknown in

the Old World, and unknown in the North American Tertiary, while

Steiromys of the Patagonian Miocene appears to be ancestral.

The primary type of the simplicidentate rodents, as I have elsewhere

shown,** must be regarded as being represented by the Ischyromyide of

the American and European Kocene, in particular by Paramys and Sciu-

ravus. All other rodents may be derived from this group by divergent,

parallel and in some respects convergent evolution. Modern rodents rep-

resent a great number of independent derivations from this primary

stock, their association into sections and families being to a considerable

extent artificial.

47 The hypothesis of migration to or from South America across a land-bridge from

Africa to Brazil is equally unsatisfactory as an attempt to explain the relations of the

hystricomorph families and is entirely at variance with the evolution and distribution of

other mammalian orders, besides being highly improbable on isostatic grounds. The

supposed evidence in its fayor from lower vertebrates and invertebrates is due, so far as

I have been able to examine it, to a lack of appreciation of the principles of dispersal

of races and of parallelism and of the imperfection of the geological record.

48 “Osteology and Relationship of Paramys and Affinities of the Ischyromyide,”’ Bull.

Am. Mus. Nat. Hist., vol. xxviii, p. 43-71. 1910.

232 ANNALS NEW YORK ACADEMY OF SCIENCES

There are no rodents in the Notostylops Beds of South America (Ko-

cene) ; presumably therefore none in preceding epochs. There are none

in the Paleocene of Europe and North America; presumably therefore

their sudden appearance in the true Eocene of these regions was due to

migration from some other region, equidistant from either, as their de-

velopment is almost equivalent in the two,—therefore probably Asia.

The few Theridomyide of the Oligocene of Africa are rather primitive

forms, certainly not more progressive than their contemporary relatives

Vy Oclodontdae Be : =

SN aly AE lyslricoimorp ‘S

Ss Dasyproclidae ae (Theridomyiade) y

—— Chinchillidae / é7 pper Hocene

| | | Cavitdde ve

and Oligocene

JVo ie erlia ry

Hystlrico-

morphs

Miocene ancestors of

Octodonts , Chinchillids and Caviids

Fic. 15.—Distribution of the Neotropical families of Hystricomorphs

The Octodontids are also found in Africa, and the Theridomyide of the early Tertiary

of Europe are apparently ancestral to these families of the Hystricomorpha. No hy-

pothesis satisfactorily explains the accepted relationship and distribution,

in Europe, affording thus a slight indication that they were Palearctic

immigrants. In Australia the evolution of Marsupial analogues of the

more abundant rodent types of Arctogwa affords strong evidence that the

true rodents were absent from Notogwa until the end of the Tertiary; a

view confirmed by the limited amount of adaptive radiation which the

invading Muride have undergone in that continent up to the present day.

The Australian Muride can only be accounted for by over-sea transpor-

tation, for the family appeared and evolved during the middle and later

Tertiary, and the peculiarities of the Australian fauna are explained by

all writers as due to isolation extending through the Tertiary period.

MATTHEW, CLIMATE AND EVOLUTION 233

TaBLe 1V.—Distribution of the Rodents

S. America | N. America Asia Europe Africa Australia

Myomor-

M yomor-

Muride and| “pha | PP oy. | Mygmor | Myomor

Hystrico- | Sciuromor- | ~~) ; é he é

Recent morpha pha ape ox eat ae Sees Muridee

Lagomor- | Lagomor- | ~* ee g ee nh ee

pha pha ia r st See eo ea

Ee eHiioon Corie) ze | pha morpha

Hystrico- ee Soka eee

E morpha Sciuromor- | Sciuromor- | Sciuromor-

Pleisto- and ha. na ahha 5 9

gene Muridz Te somor- Te omor- a omor- '

Lagomor- ah A an ‘ Pa

pia Erethizon Hystricidee | Hystricidze

1,3 Myomor-

Sciuromor- :

Pili Hystrico- vee wee See te Ree eae 2

Tene | emmornpha ‘ cha Leporidze? | pha

erat : Hystricide | Ochotonide

Leporidee y Sc

I Hystricidee

Sciuromor- Sciuromor-

meateae ys pha pha

Miocene ree Myomor- ? Myomor- i

P pha pha

Leporidee Ochotonidee

Sciuromor- Sciuromor-

pha pha

Myomor- Myomor-

Oligocene Pepalo: pha 2 pha

’ Leporidee Ochotonide | Therid -

Ischyromy- Therido- Ade

idee myide |) mye

Therido-

Bocce None Ischyro- 2 myidee 2

myidee Ischyro-

myidee

Paleocene None t None

Cretace- a

Rae None ? None

42 A hystricomorph, recorded by Ameghino from the Pyrotherium beds.

ANNALS NEW YORK ACADEMY OF SCIENCES

raw)

PERISSODACTYLA

The order Perissodactyla is represented to-day by three widely sepa-

rated families—the rhinoceroses, Ethiopian and Oriental; the tapirs,

Neotropical and Oriental, and the horses, Asiatic and Ethiopian. The

last group is the most progressive and modernized, but the whole order

must be regarded as having seen its best days and as passing towards ex-

tinction in competition with the better organized and more adaptable

=—

DISPERSAL OF THE PERISSODACTYLA

(HORSES , RHINOCEROSES ano TAPIRS)

J Distripution of Existing Horses |

ZA 5 : RniNoceroses ——~+

ROY ” » TAPIRS

@) HORSE

Surroseo Centres or Dispersal \ x

RHINOCEROS \—

@ OURING TERTIARY Perioo

TAPIR fetes /

RENE SS

AS ae

Fic. 16.—Dispersal and distribution of the Perissodactyla

The tapirs are on the whole the most primitive and their present distribution widely

discontinuous. The rhinoceroses are less widely dispersed and the horses the most cen-

tral in their present distribution. All were inhabitants of Tertiary Holarctica, but their

dispersal centers appear to have been Palearctic, as indicated.

Artiodactyla. The geological record affords abundant evidence of the

Holarctic origin of all the Perissodactyla. The ancestry of each race can

be traced back in the Tertiary faunz of Europe and the United States,

in a series of approximately ancestral stages, sometimes closer in one re-

gion, sometimes in the other, to a group of closely allied primitive peris-

sodactyls in the early Eocene of both countries. In South America, the

order is unknown until the late Pliocene and Pleistocene. In other re-

MATTHEW, CLIMATE AND EVOLUTION 935

gions we know too little of the early Tertiary faune to say when the

perissodactyls first appeared, but they are absent from the Oligocene

fauna of Egypt, from the Pleistocene and modern faune of Australia

and of all oceanic islands. This accords with the natural inference from

their size, proportions and habits that they would be strictly limited by

land connection in their geographic distribution.

Besides the surviving groups, the early perissodactyls gave rise to sev-

eral extinct families, the lophiodonts, paleotheres, titanotheres and chali-

Tertiary anceslors

of Horses

Eguidae

. 7_-f oe Pes a

(nm (ale Lerliary

Wo Eguidae

until Pleislocene.

Fic. 17.—Distribution of Equide, living (solid black) and Pleistocene (shaded)

Early Tertiary ancestors are found in Nearetic and Palearctic regions. The American

series is more direct than that of Europe until the late Tertiary. This and other con-

siderations indicate the center of dispersal as in northeastern Asia or northwestern

North America.

cotheres, none of which are known to have invaded the southern conti-

nents.

Equide—The best known phylum of the order, that of the horses, is

certainly not a direct genetic succession, as regards known species, but

approximately so as regards the known genera. The successive genera

are progressively more specialized in accordance with their geological

936 ANNALS NEW YORK ACADEMY OF SCIENCES

sequence. ‘They are identical or closely allied in the European and North

American sequence. In North America, the series is more complete, the

approximation to a direct genetic sequence is closer and the successive

stages appear earlier in time. This is reasonably interpreted by suppos-

ing that the center of dispersal was intermediate between Europe and the

western United States but nearer to the latter. That is to say, it was

either in boreal North America or in as vrs Asia. The absence of

ae TERTIARY PERIOD (QUATERNARY

EOCENE EPOCH OLIGOCENE MIOCENE PLIOCENE |PLEISTOCENE] RECENT

—— - Gees - - - - eee and North Americ )

__-!_ 7A qe = _(North America) |

| = ma (NortAl America) |

me EE | North América) |

eee | ee ae —— | <——=> (North Abnerica) |

eee America)t — — ~ te | |

qe (Biropene t--- C —

Hypohippus Ve ce America, Asia and Europe) —

— _ (North America) a Se ee

ao (North America) a

(North America)_ eR aeties

Be ees Pee (North America)_\— — ¥ —

22 REE Ee Gh Ne (South Amkrica)-: ee —_—

oe fee a kee yee (South ee aed eoy i POET (ee

Hipparion (North America , Asia , Europe and North Nafrica)

‘orth and South America, Asia , Europeyand Africa)_ = Sl

Fic. 18.—G@eologic range and phylogenetic relations of fossil Bquida

The overlap in geologic range of the genera, and the sudden appearance of each new

stage, indicate that our record is not derived from the center of dispersal of the race;

although the American series is sufficiently direct to indicate that it was not very remote.

primitive survivors of the race in the Kast Indies is natural ; as the horses

were very early adapted to open plains, unfitted for mountain or forest

habitat, the great transverse Himalayan chain would form an almost im-

passable barrier and the heavily forested regions of the East Indies would

have no attractions to tempt the ancestral horses to pass around its east-

ern end.

MATTHEW, CLIMATE AND EVOLUTION 937

TasLeE V.—Distribution of the Equide

Neotropical Nearctic Palearctic Oriental |Ethiopian

Recent Equus Equus Equus

Hquus

: Hippidion Equus Equus Pe es

Pleistocene Onoh ippi- 2 Hipparion Equus (India) Fiquus

dion, ete.

Hipparion Equus ? Equus

Pliohippus (Siwalik )

Pliocene — Mo eis Hipparion Hipparion

Parahippus

Hypolippus Hypohippus

( Hipparion

Pliohippus

Protohippus Hipparion Hipparion

| Merychippus (L’rSiwalik)

| Hypohippus

Miocene a

\ Merychippus

Hypohippus Anchitherium

Parahippus

Parahippus Anchitherium

Miohip;

Oligocene fein: ps

Mesohippus

ae Anchilophus

Es Lophiotherium

ne Orohippus Pachynolophus

Eohippus Hyracotherium

238 ANNALS NEW YORK ACADEMY OF SCIENCES

Tapiridea.—The tapirs are the most primitive living perissodactyle,

retaining the primitive number of digits in fore and hind feet and the

primitive short-crowned grinding teeth. They are to-day limited to the

Jast Indies and tropical America. In the Pleistocene, they inhabited

the Sonoran region and continental India and the marginal parts of the

Palearctic region. Their Tertiary ancestry has been traced back in Eu-

rope and in North America to the Oligocene Protapirus, which is pre-

ceded by a less direct ancestral series in the Eocene of North America;

lerkary ane lerkiry ances 0

a oe Tapirs *

Vo Tapyrs

untul Pletslocene

Fic. 19.—Distribution of the Tapirs living (solid black) and Pleistocene (shaded)

Ancestral types are found in the Tertiary formations of Europe and North America.

The relations of the two series and the Pleistocene and modern distribution indicate a

dispersal center in eastern Asia.

but ancestral tapirs have not been identified in the Eocene of Europe.

The data are insufficient to determine the center of dispersal except as

probably in the Palearctic region. Tapirs are unknown in South Amer-

ica until the Pampean (Pleistocene) ; they do not appear to have reached

Africa at all. The arid climate of the Afro-Asiatic connection and the

heavily forested path of migration to the East Indies would seem to be

the features that determined the dispersal of the horses into Africa, the

tapirs into Malaysia.

MATTHEW, CLIMATE AND EVOLUTION 939

TABLE VI.—Distribution of the Tapiride

Neotropical Nearctic Paleearctic Oriental

% Tapirus 8. s. Tapirus

Recent Tapirella None None ( Rhinocherus)

lei Teoria (al Tee SSE gees 1 Tapirus

Pleistocene apirus (s. 1.) apirus (s. 1.) | Tapirus (s. 1.) ( Rhinocherus)

Pliocene None u Tupirus (s. 1.)

2 Cp ee Lapis: (8.15) 9

Miocene None Tapiravus Paratapirus d

Oligocene None Protapirus Protapirus ?

Tsectolophus i

Eocene None Helaletes*® Lophiodontidx*! ?

Systemodon

* True affinities of these genera require revision.

51 Affinities between tapirs and rhinoceroses.

7. o / S PL Ra a

Ar ly Tertiary ancerrees

Of Rhinuoceroses

RAIROCerOseS| |

12. Midale o

la TerTeé rlia ru

Pic. 20.—Distribution of the Rhinoceroses, living (solid black) and Pleistocene (shaded)

Primitive rhinoceroses are found in the Palearctic and Nearctic Tertiaries and late

Tertiary of India and Africa. Comparison of the Palearctic and-Nearctie series indi-

cates that the center of dispersal was in west-central or southwestern Asia.

240 ANNALS NEW YORK ACADEMY OF SCIENCES

Rhinocerotida.—The rhinoceroses are intermediate between horses and

tapirs in adaptation. ‘The Tertiary history of the group is much the

same, approximate series being found in Europe and North America as

far back as the Oligocene or Eocene, but the phyla are less direct and

complete, and there is a greater diversity of type among them. The

Palearctic series appear to be more direct, and this, in connection with

the fact that the race never reached South America, may be taken to indi-

cate that the center of dispersal was Palearctic rather than Nearctic, less

northerly than that of the horses, less easterly than that of the tapirs.

At all events, the relations of the later Tertiary rhinoceroses indicate that

North America was much more remote from the center of dispersal than

Europe, while southwestern Asia was very close to it.

TasLteE VII.—Distribution of Rhinoceroses

Nearctic Palearctic | Oriental Ethiopian

Rhinoceros Ceelodonta

Non None : aa8

eeu Soe Ceratorhinus Opsiceros

Elasmotherium

: Celodonta Rhinoceros ‘

a) Ui “1 2 =

stocen None . : psiceros

Pleistocene None Opsiceros Opsiceros Opsiceros

Ceratorhinus

aisd |

Opsiceros Rhinoceros

Pliocene Teleoceras Ceratorhinus Teleoceras ?

Teleoceras Aceratherium

Teleoceras Teleoceras

Miocene Aphelops _ Aceratherium Rhinoceroses | Rhinoceroses

Diceratherium | Diceratherium |

I--

Ceenopus _ Aceratherium*

Dy, Wand s02 a) » T aac

: aus nO or th, ac-

Oligocene Prigonias Canopus | Diceratherium | Nd Perissodac

S Metamynodon Prohyracodon Teleoceras tyla

Hyracodon | Cadurcotherium

Amynodon |

focene Triplopus ; ?

Lophio|dontidee®

52 Includes a number of subgenera recently defined by Abel.

53'This family may be regarded as ancestral to both rhinoceroses and tapirs, but the

more exact derivation is doubtful.

54 Gaj fauna, upper Aquitanian auct. Pilgrim. It should perhaps be regarded as Lower

Miocene.

MATTHEW, CLIMATE AND EVOLUTION 941.

ARTIODACTYLA

The great and diverse order of artiodactyla can fairly be regarded as

of Holarctic origin as a whole. Its distribution can most readily be con-

sidered group by group.

Pigs and Peccaries.—These two groups are characteristic of the Old

and New World respectively. The pigs are now chiefly Ethiopian and

Oriental, the peccaries Neotropical in distribution. The peccaries first

reached South America in the Pleistocene and ranged throughout the

6a uced

by early me

Terliary anceslors

Of true Pgs

Tertiary ancesfors

of peccarces

No peccaries terlil

Lletstocene

Fic. 21.—Distribution of pigs and peccaries

In Old World, broken shading Sus only; full shading, other genera. In New World,

full shading Dicotyles. The dispersal center of Dicotylide was Nearctic, of Suide Pale-

arctic. The living South American genus is more primitive than the Pleistocene genera

of North America, Platygonus and Mylohyus (the Pleistocene North American species

referred to Dicotyles are all Mylohyus).

United States from the Oligocene to as late as the Pleistocene. Pigs

were common in the Oligocene and later Tertiary in Europe and were

present in India in the Miocene, probably earlier. The Tertiary ancestry

of the pigs in Europe can be traced back to a common ancestral group

in the Eocene, and the same is true of the peccaries in the western United

States.

949 ANNALS NEW YORK ACADEMY OF SCIENCES

TaBLeE VITI.—Distribution of the Pigs and Peccaries

Neotropical | Nearctic | Palzearctic | Ethiopian | Oriental

ees

Potamoche- | Sus

. 1 ; rus |

ec 20LY LES us . | °

Recent Dicotytes Sus Phacoche- | Babirussa

rus

? Dicotyles

Pleistocene | Dicotyles Mylohyus Sus

Platygonus

? Platygonus | Sus, Hippohyus

Pliocene ? Prosthen- | Platygonus | Sus | Samitherium

nOps | Potamocherus

| Listriodon

Prosthen- Sus ? Sus, Hippo-

. nops : LYUSs

Miocene None v (No record) hy ;

Potamocherus

Desmathyus | Listriodon Hyotherium

ete. Palzocherus

Paleocherus

Oligocene None Percherus | Hyotherium | None®* Palxocheerus®

etc.

?Helohyus | Cebocheru -

Eocene None ue oe ne s (No record)

Ruminants.—Under this term, we may conveniently include all the

selenodont artiodactyls,—the camels and tragulines, deer, antelopes, sheep

and cattle, besides various extinct groups.

They are admittedly of Northern origin. In South America, they do

not appear until the end of the Tertiary (Wicrotraqulus, Monte Her-

moso) ; their representatives in the Oligocene of North Africa are much

more primitive than the contemporary artiodactyls of Europe; the high-

est and most progressive types are found to-day in Asia, and the most

antique and primitive survivals in the East Indies, West Africa and trop-

ical America. The several groups indicate in their present distribution,

and in what is known of their past history, that their centers of dispersal

55 Schlosser has shown that Geniohyus is a Hyracoid, not an Artiodactyl.

°° Gaj fauna, regarded by Pilgrim as upper Aquitanian.

MATTHEW, CLIMATE AND EVOLUTION 942

were in different parts of the northern world, as we have seen among the

Perissodactyl groups.

The camels appear to have been of American origin. An ancestral

series is found in the Tertiary of the western United States, going as far

back as the Upper Eocene.** In the Old World, they first appear in the

Phocene; in South America, in the Pleistocene (Pampean) ; and the

Lerliary Anceslr

of the Cametltaae

{

until Pleislocene

Fie. 22.—The dispersal center of the Camelide was in North America

They reached the Old World in the Pliocene, South America in the Pleistocene. They

survive on the margins of their range but became extinct in North America early in the

Pleistocene. North American Pleistocene camels were more advanced than the living

types of the marginal areas.

camels of the Pleistocene in North America were about as specialized on

the whole as the living llamas of South America or the camels of Africa

and Asia. In North America, the race is now extinct. The center of

dispersal would appear to have been in this continent,—how far to the

north we have no means of estimating; but the exceptional directness of

the phylogenetic series as represented by our western fossils indicates, in

my opinion, that these fossils lived in or close to the racial dispersal

center.

57 It forms a singularly direct and complete phylum, so supercharged with intermediate

and connecting forms that it is very difficult to classify and arrange the fossils into

species and genera, while every gradation of structural evolution is abundantly illus-

trated.

244 ANNALS NEW YORK ACADEMY OF SCIENCES

TaBLE 1X.—Distribution of the Camels

Neotropical Nearctic Paliearetic | Ethiopian Oriental

Recent Auchenia None Camelus None None

Bschatius Camelus

Pleistocene | Auchenia Camelops ? Procam- te Camelus

Camelus elus °°

Miaucheni 9 Parac c

Pliccane None Pliauchenia Lee anacam ? Camelus ®

ete. elus

—_—__—_— (No record) =

Procamelus

a is Protolabis = =

Miocene None Miolabis ete. None None

Oxrydactylus

Protomeryx

: - ete. = r r

one F i . None No recoré

Oligocene None | Poébrotherium None None (No record)

| Hotylopus

Hocene None Protylopus None (No record)

The tragulines, recent and extinct, are a heterogeneous assemblage of

primitive ruminants, whose real affinities have been much disputed. In

the present writer’s opinion, the living East Indian cheyrotains should

be associated with Hypertragulus of the North American Oligocene and

perhaps Microtragulus of the South American Pliocene, and the center

of distribution of this group hypothetically placed along the northeastern

coast region of Asia (cf. tapirs). The living water-chevrotain (Hye-

moschus) and most of the so-called tragulines of the European Oligocene

and Upper Eocene are to be regarded as primitive stages of true Pecora.

Leptomeryx, Protoceras and Heteromeryx are related forms from the

North American Oligocene. Among these primitive forms, some (Lep-

fomeryx) display affinities to the deer, others (Protoceras, Heteromeryx)

to giraffes and antelopes.

580, sivalensis of the Siwalik beds is doubtfully congenerie with the modern species

and, along with the so-called Procamelus described by Mme. Payvlow from the Pleistocene

of Russia, appears to be an intermediate stage between Procamelus and Camelus.

59 A doubtful Camelid, based on a single upper molar from the Pliocene (or Miocene)

of China.

MATTHEW, CLIMATE AND EVOLUTION

SDT

In the later Oligocene of Europe and the Miocene of the United States

appear more definitely deer-like types (Dremotherium, Blastomeryz),

and in the succeeding formations we find progressively higher types of

deer in Europe and North America, but always appearing earlier in the

Old World. The deer—-excepting the isolated primitive survival repre-

sented by the “water-chevrotain,” closely related to Dorcatherium, a

Miocene genus in Europe—have not reached the Ethiopian region, but

Leplomeryx in Dorcatheriumy =

mid-Lerliary ; Cervi mid-Terliary; Cervidae~

tn laler Tertiary A tn later Terhiary

No Cervidae = By 9 moschus =

until Plecs locene cf Dorcalh?m) ==

Rangifer, Alces, Cervus canadensis and allies

YS Other Cervidae , primilive lypes mostly in Tropes

Fic. 23.—Distribution of Cervide and pro-Cervid Tragulide

The highest and latest appearing types are still confined to the circum-Arctic regions ;

the genera of the more peripheral regions are more primitive. The earliest and most

direct ancestral series is found in Europe and Asia; the parallel series in North America

is less direct and more retarded. A primitive survival is found in West Africa, pro-

tected by the desert from competition of higher types.

were easily able to reach North America in the Pleistocene. I take it,

therefore, that their center of dispersal was well to the east and north in

Asia (cf. horses). Their migration into the Ethiopian region was checked

after the Miocene by the progressive aridity of the desert region between,

246

ANNALS NEW YORK ACADEMY OF SCIENCES

which served as a barrier to these forest-living ruminants, although not

to the plains-living antelopes.

TABLE X.—Distribution of Tragulide proper

Recent

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Neotropical Nearctic Palearctic | Ethiopian Oriental

None None None None Tragulus

None None None | None Tragulus

?? Microtrag- E

AS None None Tragulus

None None ? None None

[Hypertrag-| 57,1,

None ulus] ? None None None

None [Primitive Artiodactyla ]|

MATTHEW, CLIMATE AND EVOLUTION 947

TABLE XI.—Distribution of Cervide and Pro-Cervid Tragulines

Neotropical | Nearctic | Paleearctic | Ethiopian Oriental

Cervus, Cervus, Hyemos-

R t Odocoileus Alces Alces chus Cervus

eee! Mazama Rangifer Rangifer, (W. Afri- (sensu lato)

Odocoileus Dama eae

Cervus, eee

: Odocoileus Alces vets Tene

Pleistocene Tigenan Rangifer UN : Cervus (s. 1.)

Odocoileus Megaceros

Cervus (s. 1.)

‘ Cervus Cervus Lae Moschus

sinveene None (Sale) (Sil) mete: (No record) Doreathe-

rium

Bee £ eS N 1) Dorcathe-

i J 0 recorc “ium &

Btiocene pone Blasto- Dremothe- ( aes

meryxr rium

Lepto- ioe a Prodremothe-

Oligocene None merys | eer 5 ie None rium

ete. GeOCus Gelocus ete.

ete.

Eocene None Primitive Artiodactyla No record

The antelopes, on the other hand, while also appearing fairly early in

the European geologic record and abundant and well advanced in south-

west and southern Asia as early as that record is revealed to our eyes, are

imperfectly represented in North America—first appearing in the Plio-

cene and not widely varied even to-day, while they have not reached South

America at all. They are to-day most abundant and varied in Africa.

From these facts, I infer that their center of dispersal was well to the

6 Family is structurally ancestral to American

Cervide.

% This group is referred generally to the Tragulide, but the common characters are

persistent primitive features, and I regard it as a little altered survivor of the ancestors

of the Cervide. Tragulide as here limited are a distinct phylum, primitive in many~

features but aberrant in others.

® Family Tragulide as usually referred, but affinities are with Hyemoschus, not with

Tragulus; the group may fairly be regarded as ancestral to the Cervidwe, while the

traguline group certainly is not.

Hypertragulide, but Leptomeryr

248 INNALS NEW YORK ACADEMY OF SCIENCES

C. Other Antelopes (Antelopine etc.) D. Cattle (Bovine)

Fig. 24.—Distribution of the Bovide, existing (solid black) and extinct (shaded)

The sheep and goats are regarded as the highest group; the muskoxen represent a

specialized Arctic adaptation (cf. Eskimo among mankind). ‘The cattle are a somewhat

southerly type; their formerly wide northern distributfon has been greatly restricted,

and for the theory that they are of Oriental origin there does not appear to be any real

evidence. The remaining Bovid subfamilies, usually grouped under the term “‘antelopes,”’

are to a varying extent primitive and aberrant. The Holarctic groups are nearer to the

sheep and goats and the more primitive groups are limited to the Ethiopian region and

the East Indies.

MATTHEW, CLIMATE AND EVOLUTION 249

west and south in Asia (cf. rhinoceroses). The sheep and goats are a

comparatively recent development of the highest antelopes and must be

assigned a center of dispersal somewhat more to the north.

The cattle’ are of comparatively recent appearance in Europe, as also

in America. Judging from their present distribution, one would say

that their center of dispersal was in southeastern Asia, the southward

slopes of the Himalayas.

Fic. 25.—Distribution of the Giraffes, existing (solid black) and extinct (shaded)

On present evidence their dispersal center would appear to have been in south central

Asia. But the affinities of the Tertiary Giraffide to other contemporary ruminants need

careful and judicial reconsideration.

antelopes. This inference from their modern distribution conforms with

the geological record. They appear suddenly in the upper Miocene of

Europe, but an ancestral series is found in India as far back as the upper

Oligocene.**

The giraffes have approximately the same center of dispersal as the

83 See G. E. PILGRIM: Rec. Geol. Sur. Ind., vol. xliii, p. 301. 1913.

250 ANNALS NEW YORK ACADEMY OF SCIENCES

TABLE XII.~—Distribution of Bovide and Antilocapride

| Neotropical | Nearctic Paleearctic Ethiopian Oriental

Ovis Sheep and

Cattle

oy Spann Oreamnus Goats !! e Cattle !!

Recent None Bison Cattle * ae git | Antelopes!

| Antilocapra | Antelopes Rein

' Sheep and

Bison

aa 7 ae Goats Cattle Cattle

Pleistocene | NOE etka Cattle! Antelopes | Antelopes

B Antelopes!

Cattle! !

ae eer [Meryco- Cattle :

Pliocene oe dus |" Antelopes !! ce

lopes!!

2 —_—_——__—— (No record)

| pak Antelopes!! Cattle!!

Miocene None Ease aye % (late Mio- Ante-

| a cene) lopes!!

| [Ancestral

Oligocene | None None Primitive None None

Ruminants |

6 Merycodus is a distant relative, combining characters of Bovide and Cervide.

MATTHEW, CLIMATE AND EVOLUTION 251

TABLE XIII.—Distribution of Girafide

Nearctic Palearctic Ethiopian Oriental

= Giraffa |

Recent None None Ocapia

Pleistocene None None

Sivatherium

i None (unless Hydaspithe-

9 “

Pliocene ? None in China) (No record) AP

Giraffa ete.

Felladotherium ? Giraffa

Miocene ? None Samotherium (Norecord) | Progiraffa

etc. ete.

[Syndyoceras | Ancestral ree miley

Oligocene and Proto- Primitive None : phe @inat

ceras © Ruminants fide) i

6& Remote and archaic collateral relatives, family Protoceratide.

eertain that Dromomeryx and other

undescribed

It is by no means

genera from the North American

Miocene provisionally referred to the Cervide and Brachyodont Bovide are not related

to the Giraffide ; but on present evidence the dispersal center of the family appears to

be India, and their range confined to Palwogea.

252 ANNALS NEW YORK ACADEMY OF SCIENCES

Besides these surviving groups of ruminants, there are several groups

which have not survived. The anthracotheres are one of the earliest of

these specialized races; I have elsewhere®® detailed the data upon which

may be predicated a North Asiatic center of dispersal for this group.

The living hippopotami show a modicum of resemblances to this type,

which may mean that they are derived from some early members of it.

Their present habitat is Ethiopian; but inthe Pliocene and Pleistocene

their range was far to the northward—even as far as England on one

OX Anthracotheres We a Z- Terliary

LEG flippopolame / wa Jiocene ana Ea

ay Modern Hpppopolamé

Fic. 26.—Distribution of the Anthracotheres and Hippopotami

The Anthracotheres were a large and widely dispersed group in the Oligocene and

Miocene, especially in the Old World, but found also in the Oligocene of North America.

The Hippopotami appear to be specialized survivors from the same stock; they are con-

fined to the Old World and their range has been greatly restricted since Pliocene and

Pleistocene.

hand and northern India on the other. While the present distribution

of the large hippopotamus is Central Africa, smaller and more primitive

precursors have been stranded on the one side in West Africa, on the

other (now extinct) in Madagascar and also found refuge in the Mediter-

ranean islands until the Pleistocene. (The aquatic habits of the hippo-

6 Bull. A. M. N. H., vol. xxvi, pp. 1-7. 1909.

MATTHEW, CLIMATE AND EVOLUTION

253

potamus have enabled it to reach these island retreats more easily than

terrestrial competitors. )

TaBLE XIV.—Distribution of Anthracotheres and Hippotami

Nearctic Palearctic | Ethiopian Oriental Malagasy

Hippopota-

Recent None None Mus None None

Cheropsis

Hippopota- Hippopota-

Pleistocene | None Choro - Hippopota- Miss

wie OP mus (dwarf

( Gupcns) species)

Hippopotamus

* Hippopota- : Hexaprotodon

Pliocene None aie (No record) | 4, erycopota-

MUS

(No record)

Anthraco-

therium

Miocene Arretothe- | Brachyo- | Anthraco- | pomimerye

rium dus theres Sivamerysx

ete.

Merycops

Anthraco- ie ob Aes 8

Anthraco- therium “Brachyo-

Oligocene therium | Ancodus Ancodus dus”? (No record)

Ancodus “Brachyo- Anthraco-

dus” therium

Eocene None Ancodus (No record)

The remaining groups of ruminants are not of especial interest in this

The entelodonts are Holarctic; the oreodonts Nearctic;

anoplotheres and cenotheres Palearctic; there is no evidence that they

originated elsewhere or that they reached any other zodlogical region.

Entelodon (sensu lato) appears simultaneously in Europe and the United

discussion.

87H. minutus is (fide Bate) congeneric with the Liberian species.

The rules of pri-

ority call for the application of Hyopotamus Kaup to this genus, instead of Chwropsis.

254 ANNALS NEW YORK ACADEMY OF SCIENCES

States in the beginning of the Oligocene, without direct ancestry in either

continent, and is regarded by Peterson®* as probably from an Asiatic

source.

NON- RUMINANT

PECCARIE 0

CSS

PLEISTOCENE

PLIOCENE

Ni,

ara

ratatatat

MIOCENE

OLIGOCENE

Ws,

Wei

0.9 ,y,

iX?

Uff

LLL

OF THE

EOCENE - HIGHER GROUPS OF RUMINANTS

PALAARCTIC ETHIOPIANKORIENTAL

Fig. 27.—Phylogeny and distribution of the Artiodactyla

YR “

Most of the families appear to have originated in the Nearetiec or Palearctic region

and spread thence outwardly to the more peripheral regions. The higher types are of

more recent origin and are still dominant in the Holarctica.

PROBOSCIDEA

The later Tertiary and Quaternary history of the mastodons and ele-

phants agrees with the various groups that we have been considering in

indicating Asia as the center of distribution of the race. Elephants are

now limited to the Ethiopian and Oriental regions, but in the Pleisto-

cene their range was over the whole of Europe, Asia and North America,

as well as Africa. The northern species, although of smaller size, are

more progressive than the southern species in the specialization of the

teeth, proportionate length of tusks, shortening of skull with concomitant

elongation of trunk. The more primitive mastodons first appear in India

in the Oligocene, in Europe in the lower Miocene, in North America in

the middle Miocene. The intermediate stages leading to the mammoths

and elephants are best shown in the Pliocene and Pleistocene of India; a

less exact series may be found in North America. The mastodons reached

South America in the Pleistocene; the mammoths and elephants never

reached that continent. The earlier stages in the phylogeny of the Pro-

6 QO, A. PETERSON: Mem. Carn. Mus., vol. iv, pp. 145-148. 1909.

MATTHEW, CLIMATE AND EVOLUTION 955

boscidea have not, however, been found either in Europe or North Amer-

ica but have been recognized in the Oligocene of Egypt. From this fact,

it has been generally concluded that the Proboscidea first evolved in the

Ethiopian region. But it should be remembered that northern Egypt is

not strictly within the Ethiopian region but belongs with all of northern

Africa to the Mediterranean subregion of Holarctica. Owing to its prox-

imity to the Ethiopian region, it contains Ethiopian elements in its mod-

ern fauna and may have contained more in the past. But it is not clear

that the Oligocene Proboscidea must be numbered among these. There

is no evidence that their center of dispersal was not Asiatic in early as in

later Tertiary ;°° but it must have been too far to the south to admit of

their reaching Europe or North America, until after their spread into

northeast Africa. We must therefore conclude, apparently, that the dis-

persal center was transferred to the north and east during the course of

the Tertiary—a quite exceptional feature, beside which the question of

its original location, whether in southern Asia or in Africa, appears much

less important.

TABLE XV.—Distribution of the Proboscidea

Neotropical | Nearctic Palearctic | Ethiopian Oriental

Recent None None None Loxodon Elephas

Hlephas

: : Elephas Hlephas :

Pleistocene | Dibelodon jeetianien, | aepetracien ? ene 2

Hlephas

Pliocene None Dibelodon a Wate (No record) | Stegodon

lophodon

Trilopho-

is . : Tetralophodon

Miocene None nee ho D ie oe D mone Trilophodon

= Dinotherium

rium

Paleomas- | Heniimasto-

F todon don

Oligocene | None Neue Merithe- | Dinotherium

rium ? Meritherium

Merithe-

Eocene None None None Pi (No record)

® Certainly the Proboscidea of the Oligocene Gaj fauna of India are far more ad-

vanced than the Egyptian Fayfim genera, if Pilgrim’s correlation of the Gaj beds is cor-

rect.

This, by our methods of interpretation, would indicate that India was much

nearer than Egypt to the dispersal center.

256 ANNALS NEW YORK ACADEMY OF SCIENCES

SIRENTA

The most primitive sirenians are found in the late Eocene of Egypt.

As these were apparently contemporary with more progressive types in

the Middle and Upper Eocene and Oligocene of Europe, they indicate, if

anything, that the Mediterranean shores hald a less progressive fauna

than the North Atlantic. The Oligocene and Miocene types are approxi-

mately ancestral to both the modern groups, manatees and dugongs. Ap-

parently the manatees became characteristic of the North Atlantic, the

dugongs of the Indian Ocean shores. The progressive cold of the later

Tertiary and Pleistocene has driven the manatees out of the Arctic and

northerly Atlantic shores and their northern limit is now Florida on the

western, and the African coast on the eastern side. They have not been

found fossil north of 40° N. lat. on the American coast,’® for the excel-

lent reason that there are practically no Tertiary littoral deposits north

of that latitude.

The occurrence of Manatus in West Africa and in the West Indian and

South American coasts is among the arguments used in support of a

transatlantic bridge; but there is no evidence at all that the ancestors of

Manatus did not inhabit the whole of the North Atlantic and Arctic

basin during the Tertiary. It is certain that they did inhabit parts of

the intervening European and American littoral, and the negative evi-

dence elsewhere is obviously worthless, because there are no formations

known in which they might be found.

CONDYLARTHRA AND SPECIALIZED SUCCESSORS

We may here consider the distribution of a number of extinct groups

of Tertiary ungulates or semi-ungulates, whose rise and culmination took

place at an earlier epoch and under different conditions from those which

we have discussed. ‘The Condylarthra are an extremely primitive group

of hoofed mammals, fulfilling nearly the theoretical requirements for the

common ancestral type of all placental ungulates. The earliest known

artiodactyls and perissodactyls are, however, too much specialized to be

immediately derived from the known Condylarthra. Condylarths first

appear in the Paleocene of North America and Europe and in South

America in the Notostylops fauna, here regarded as Eocene. In North

America, they develop through the Taligrada into the Amblypoda, culmi-

7 Yor distribution of manatees during Tertiary vide Hay, Bibl. Foss. Vert. N. A., U. 8.

G. S. Bull. 179, p. 583-4, 1902; of Old World Sirenians, Abel, 1904. Abh. Geol. Reich-

sanst., xix Bd., s. 214; 1906, Neues Jahrb. Bd. ii, s. 50-60; 1912, Palwontographica,

lix Bd., s. 292.

MATTHEW, CLIMATE AND EVOLUTION 257

nating in the highly specialized Dinocerata. In South America, they

apparently develop during the Tertiary in absence of Artiodactyla and

Perissodactyla into a great variety of hoofed mammals, the Toxodontia

and Typotheria, Litopterna, Astrapotheria, Pyrotheria. The Arsinoi-

theria of the Oligocene of Africa, perhaps also the Hyracoidea and Probo-

scidea, may also be regarded as evolved from primitive Condylarthra, in

absence of the higher ungulates of the Asiatic center of dispersal. We

have therefore direct or inferential evidence that at the beginning of the

Eocene the Condylarthra inhabited the Palzarctic, Nearctic, Neotropical

and Ethiopian regions. There is no reason to suppose that they were

ueeat NOTOUNGULATE Bae x z (|

Crelacéc BU NOTHE RIA

RQ Palaearciic. GG, Wearelic. — Meotropicel|I| [III] Ethiopian and Oriental

Fic. 28.—Relationship of the Condylarthra to the Notoungulate and Subungulate groups

of hoofed mammals

In indicating the distribution, Egypt, Syria ete. have been included with Ethiopia, as

the essential facts in this case could thus best be represented. ‘“‘Bunotheria”’ are the

common ancestral stock (hypothetical) of the Creodonta-Carnivora-Condylarthra-Ambly-

poda group.

absent from the Oriental region, but they evidently did not reach Aus-

tralia or Madagascar.

The worldwide dispersal of the condylarths at the opening of the Ter-

tiary (partly hypothetical and exclusive of Australasia and Madagascar)

may be regarded as due to the epoch of elevation and disturbance which

closed the Cretaceous. The subsequent development of peculiar and

highly specialized ungulates during the Eocene in the several great con-

tinents is attributable partly to the isolation of these continents during

that period due to submergence of the low lying connecting regions,

258 ANNALS NEW YORK ACADEMY OF SCIENCES

partly to the prevalence of more uniform climatic conditions all over

the world and the consequent lack of environmental pressure tending to

force a change in habitat. Towards the end of the Eocene began a

period of progressively intensified elevation and disturbance, with re-

frigeration of climate beginning at the poles; this culminated in the

Glacial epoch. ‘The northern fauna suecessively invaded the tropical

and southern continents and swept before it ‘nearly all their autochthonic

faune.

In Africa, we see this invasion in progress in the Oligocene; the

anthracotheres, forerunners of the great ruminant invasion have already

appeared; to these may yet have to be added Palwomastodon as a fore-

runner of proboscidean invaders (although on the present record the

Proboscidea may appear an autochthonic group); while the hyracoids,

with Meritherium, Arsinottherium, Barytherium and some less known

types are apparently autochthonic since Paleocene. Unfortunately, our

view stops here; we know little of the progress of this invasion until the

late Pliocene, when these invaders had themselves disappeared before a

succession of later invasions or become modified into new types.

In South America, the isolation lasted much longer, and owing to the

great southward extension of the continent, a highly progressive inde-

pendent center of dispersal was set up in Argentina. Whatever criti-

cisms may be made of the phyletic theories of Dr. Ameghino, so far as

they affect the evolution of the mammalian races of the northern world,

I think that there can be no question that he has brought out a remark-

ably complete series of phyla in the autochthonic races of South America.

The closeness of these series, and the large amount of progressive evolu-

tion which they involve, on lines analogous to those of the northern

mammals, are fair indices that the controlling forces were similar and

that the southern end of the continent was the chief center of dispersal.

The various types of structure which were developed in northern mam-

mals during the Tertiary, in adaptation to the progressive change of

environment, are almost all paralleled, occasionally exceeded in degree

by these southern races; but they are very generally seen in different

combinations, as Professor Gaudry has so clearly shown.™4

Had the Condylarthra reached Australia, we should expect to find

there a group of placental ungulate orders peculiar to the region, like

those of Tertiary South America, persisting to the present day. But we

find, instead, that the marsupials evolved into the herbivorous fauna.

In Madagascar the lemurs may be regarded as filling the place which

T ALBERT GAUDRY: Annales de Paléont., t. ill, pp. 41-60. 1908.

MATTHEW, CLIMATE AND EVOLUTION 259

primitive ungulates would have taken, if they had reached the island;

but the case is not so clear.

EDENTATA

The edentate orders afford among the unguiculates a broad parallel in

their distribution and history to the Condylarthra and their successors

among the ungulates. Their extinction has been somewhat less complete ;

a few highly specialized survivors remain in the Neotropical, Ethiopian

and Oriental regions.

Gly plodonis and Ground-sloths

a Tee

[Eas ———

Ss Pholitola andd

Lubulidentata

Dis pe

Xenarthra throughout Ter lary

Wi, Xenarthra INS Photidola {II | Tubulidentata

Fic. 29.—Distribution of the Edentate orders

The New World edentates or Xenarthra may have originated in Cretaceous North

America, but their Tertiary dispersal centers were South American, apparently in or

near to Patagonia. The dispersal centers of the Pholidota and Tubulidentata would

appear to have been Palearctic, but very little is known of their fossil record.

The super-order Edentata is an artificial assemblage including the

three surviving orders Xenarthra, Pholidota and Tubulidenta and the

extinct order Tzeniodonta (= Ganodonta). The Teniodonta of the Ho-

cene of North America may perhaps be regarded in a broad way as rep-

resenting the primary type of the Xenarthra, but even this is doubtful.

260 ANNALS NEW YORK ACADEMY OF SCIENCES

They are far more primitive and nearer to the generalized eutherian

type; but they show certain unique Xenarthran peculiarities in foot-

construction and in the pelvis, and the dentition in the two known phyla

progressively evolves on lines leading towards, although not into, the

PHYLOGENY OF he: aD ENT Ais

ARMADILLOS ANTEATERS _TREE-SLOTHS

i Wn ae RR

We ‘hd

(mad BN a GLYPTO nts kone LOTHS

\ ‘S see \

FER KES, \ ‘y

CaN

y PLY

Nearclic

North American)

, \\\\ ) Weolropical

(South American)

CRETACIC

Unknowte

Fie. 30.—Distribution and phylogeny of Xenarthra and Teniodonta

The aberrant North American groups appear to be relicts indicating a northern origin of

the Xenarthra, but the evidence is not conclusive.

MATTHEW, CLIMATE AND EVOLUTION 961

specialized edentate types. The xeniodonta range from Paleocene to

Upper Eocene in North America and are doubtfully recorded in the

early Eocene of Europe. They may be hypothetically regarded as a

Cretaceous-Eocene ancestral group in the northern world, from whose

early members budded off the ancestral Xenarthra in the Nearctic, pos-

sibly also the Pholidota and Tubulidentata in the Palearctic, the whole

group being driven southward at the beginning of the Tertiary, except

for a few lingering remnants, rare and little known. Of these lingerers,

we may instance in the (Bridger) mid-Eocene of Wyoming Metacheir-

omys, whose affinities are distinctly armadilloid and an unnamed but

more primitive genus in the Lower Eocene of Wyoming approximately

ancestral to it; “Lutra” franconica of the Oligocene of Germany, shown

by Schlosser to be related to the Aardvark, Palwomanis and Orycteropus

of the Miocene of Samos, and more doubtfully Palworycteropus and

Necrodasypus (in part) of the Oligocene of France.

Whether the rare ground-sloth remains from the (?) Middle Miocene’

and Lower Pliocene of the western United States are to be regarded as

surviving Northern edentates or as immigrants from the south is not

certain, but the latter explanation is more probable.

The Old World edentate groups, although still surviving in Ethiopia

(Manis, Orycteropus) and the East Indies (Manis), are not known to

have undergone any considerable expansion during the isolation-period

of the early Tertiary.7** The Xenarthra, on the other hand, are first

represented in the early Tertiary of South America by armadilloid forms

and they blossomed out in the isolated continental conditions that pre-

vailed during the Tertiary in that continent into a wide range and

diversity of type, just as the Condylarthra appear to have done under

the same conditions there and the marsupials in Australia. Of the five

principal groups—tree-sloths, ground-sloths, anteaters, armadillos and

glyptodonts—only the second, fourth and fifth are known as fossils, and

only the first, third and fourth have survived. The fossil groups reached

their maximum of size and specialization in the Pleistocene, and rein-

vaded North America in the Pliocene and Pleistocene (possibly earlier,

“= There is some question as to the true horizon of the ground-sloth claw found by

Sinclair in the Mascall formation (Middle Miocene) of Oregon. The specimen may have

washed down from the overlying Rattlesnake Beds, Lower Pliocene [oral communication

from J. C. Merriam].

73 But this may be due only to the imperfection of the geologic record. We know

nothing of the early Tertiary faune of the Ethiopian and Oriental regions, save for the

Oligocene of Egypt. The Eocene faune of South Africa, India and the Bast Indies may

have included a considerable expansion of pholidate or tubulidentate mammals, corre-

sponding to the xenarthral expansion of the New World, but earlier extinguished because

of the earlier invasion of those regions from the north.

962 ANNALS NEW YORK ACADEMY OF SCIENCES

vide supra), but only the armadillos have maintained any foothold in

the northern world until modern times and these only in the southwest

corner of the Sonoran region. ‘The anteaters and tree-sloths might be

expected to have originated in Patagonia and to have been driven north-

ward to tropical South America in accord with the theory of climate and

evolution here advocated. The geological record, however, has failed to

show any certain evidence of this, and, as the Patagonian record is a com-

paratively full one, this fact should be counted as evidence that climatic

change is not the only causal factor of evolution. We must suppose, if

the record be adequate, that these groups originated and evolved in tropi-

cal South America. The armadillos are an extremely persistent group,

and the record gives no really convincing evidence of a Patagonian dis-

persal center, although it might be so interpreted.

Glyptodonts and ground-sloths appear in the Pliocene and Pleistocene

of North America. The Pleistocene genera except Megalonyzx are closely

allied to the genera of the Pampean formation, in part identical there-

with (Brachyostracon, ? Glyptodon, Chlamydotherium, Megatherium,

Megalonyx, Nothrothervum, Mylodon). These, or allied genera equiva-

lent in specialization, inhabited South America from Ecuador to Pata-

gonia in the late Pliocene and Pleistocene. The only genera found in the

Pliocene of North America are Megalonyx and Glyptotherium, decidedly

more primitive and are best interpreted as earlier forerunners of the main

invasion which appeared at the beginning of the Pleistocene. Mylodon

has been recorded from the Blanco beds of Texas, but this is an error.

MARSUPIALIA

Marsupials are at present almost limited to the Australian and Austro-

malayan region, where, in the absence of placental mammals, they have

diversified into a wide variety of size, habits and adaptation, paralleling

the adaptive radiation of the higher mammals in the northern continents.

A single unspecialized group, the opossums, representing quite nearly the

primitive type from which all marsupials are derivable, survives in the

Neotropical region, one or two of its species ranging northward into the

Sonoran subregion of Holarctica. Another primitive survivor in the Neo-

tropical region is the rare little Cenolestes, formerly regarded as a primi-

tive member of the diprotodont marsupials, but now considered to be of

polyprotodont affinities, its diprotodont resemblances being due to paral-

lelism.

What we know of the paleontology of the order is in complete accord

with the theory of their being primarily of northern origin, their dispersal

preceding that of the early placentals.

MATTHEW, CLIMATE AND EVOLUTION 263

The fragmentary and little known mammals from the Mesozoic for-

mations of Europe and North America were in large part marsupials, so

far as we can judge from what is known of them.

The most distinctive group among them were Multituberculata or

Allotheria. Gidley’ has recently (1909) brought forward strong evi-

dence for the view that these animals were an archaic, early specialized

branch of the marsupials paralleling the later diprotodonts.7* They

occur (doubtfully) in the Rheetic of Germany, certainly in the Upper

lerliary Opossums probabl:

Opossums Since Crelgced S3 :

Borhyaenizs unrecerded /72 Pha (29 gers:

Caenolestias lalér Ter lary only

Opossums i'n

early Terliar

Thylactnus

MAustralia (7

=. Pleistocene :)

—.

——

— 7

—

tify Qpossiiis, = Caenolestes SSN Dasyures;Diprotodontia

Fic. 31.—Distribution of Marsupials

This is probably to be regarded as due to a very ancient dispersal from the north, fol-

lowed by differentiation and dispersal during the Tertiary of specialized adaptations

parallel in the Neotropical (Borhyenids and Cenolestids) and Australian regions (Thy-

lacine-Dasyures and Diprotodonta). ‘The Phalangers of the Austromalayan islands are

regarded as marginal types from an Australian dispersal center.

74 J. W. GIDLEY: Proc. U. S. Nat. Mus., vol. xxxvi, pp. 611-626. 1909.

7 Recent discoveries, made since these lines were written, indicate that the relationship

was not as close as had appeared. Dr. Broom has even maintained that these animals

were nearer to monotremes than to marsupials, but in my judgment he has failed to

adduce any really valid evidence for this view. But while they are in the Metatherian

stage of evolution I do not think they can be included in the order Marsupialia on the

data now available. See forthcoming article by Walter Granger in Bulletin Am. Mus.

Nat. Hist.

964. ANNALS NEW YORK ACADEMY OF SCIENCES

Jurassic and Lower Cretaceous of England (Plagiaulaz™*) and Wy-

oming (Ctenacodon). They again appear in the uppermost Cretaceous

and Paleocene of North America (Lance formation of Wyoming, Fort

Union of Montana, Puerco and Torrejon of New Mexico) and Europe

(Cernaysian) in the genera Ptilodus, Neoplagiaulax, Polymastodon and

Meniscoéssus. They are questionably recorded in the Eocene Notostylops

beds of Patagonia, in the genera Propolymastodon, Polydolops ete. (which

more probably belong to the same group as Cwnolestes). They are not

known elsewhere except for part of a jaw from the middle Cretaceous

(Belly River) of Canada and a jaw (Karroomys) from the Jurassic

(Karroo beds) of South Africa. The front half of a skull long ago found

in the Karroo beds and described as T’ritylodon is probably to be referred

to this group, although its mammalian nature has been questioned.**

In addition to the Multituberculata, there are in the Jurassic and basal

Cretaceous of England and Wyoming a number of mammals with simpler

and more numerous teeth whose affinities are very uncertain. Whether

they are ancestral to marsupials, to placentals, to both or to neither is,

in the writer’s opinion, an unsettled question. Its definite solution must

probably await the discovery of more complete material.

In the uppermost Cretaceous (Lance formation) of Wyoming are found

in addition to teeth and jaw fragments of Multituberculata, a variety of

tritubercular teeth, some associated with fragments of the jaw. These

appear to be more definitely referable to the polyprotodont marsupials ;

some of them may be quite near to the opossum. I have seen no evi-

dence among them of placental mammals, although most of them are too

fragmentary to exclude the possibility of the presence of Eutheria.

The Paleocene fauna of New Mexico, Montana and France contains

numerous placentals and a few Multituberculata, but no polyprotodont or

true diprodont marsupials have yet been positively recognized in it. It is

evidently not derived (except for certain of the Multituberculata) from

the fauna of the Lance formation. Yet it is almost, perhaps quite, con-

temporaneous with it and must be supposed to represent a distinct facies

of the fauna, differing in habitat from that of the Lance formation (the

Fort Union is partly intermediate). Polyprotodont marsupials certainly

persisted in North America and Europe, for we find the remains of

species nearly related to the existing opossums in the Lower and Middle

7% Bolodon is a synonym of Plagiaulaa, fide Gidley.

7 Broom has recently made a careful restudy of the affinities of Tritylodon, and con-

cludes that it is a mammal, but not closely related to the marsupials, and represents an

archaic specialization with many primitive characters inherited from the cynodont

reptiles. R. Broom: Trans. S. Af. Phil. Soc., vol. xvi, pp. 73-77. 1905. Proc. Zodl.

Soc. London, 1910, pp. 760-768. 1910. Bull. Am. Mus. Nat. Hist., vol. xxxiii, pp. 115-

134. 1914.

MATTHEW, CLIMATE AND EVOLUTION 265

Eocene of Wyoming, in the Oligocene of Colorado and in the Upper

Eocene to lower Miocene of France and Germany. They are not known

from any later formation in any of the northern continents.

In the Southern continents, they assumed a much more important

position. In South America, in the absence of placental carnivora, the

polyprotodont marsupials developed into a number of large and small

predaceous mammals (Borhyenide), so closely paralleling some of the

predaceous marsupials of Australia that they have been referred to the

same family (Thylacinide). Pseudo-diprotodont marsupials were also

fairly common, taking the place in the fauna held by Insectivora in the

North, this group of placentals (except for a single type) not having

reached South America. The marsupials of South America did not de-

velop into groups taking the place of northern ungulates, rodents or

primates, since primitive placentals of these groups (Condylarthra,

? Hystricomorpha, ? Lemuroidea) had penetrated into South America

before it was separated from the Northern world, and there developed

along lines sub-parallel to the development of the higher placental groups

in the North, but distinct and less progressive.

In Australia, the marsupials assumed a still more important position,

as the only mammals of that continent. The placental mammals of the

northern Tertiary did not reach Australia, except for a few strays—bats

and mice and the dingo—which were too few in numbers and of too re-

cent introduction to affect seriously the course of mammalian evolution

on that continent. In the absence of placentals, the marsupials developed

into a wide variety in size, form and habits of life, partially paralleling

the higher mammals. .

The near resemblance between the modern Australian Thylacinus and

the Borhyzenide of Tertiary South America has been used as an argu-

ment for an Antarctic connection between the two. Such a hypothesis

will not bear close examination. The resemblance is not closer than

between parallel adaptations in distinct families of true Carnivora, whose

genealogy has been more or less completely traced back through inde-

pendent lines of descent from unspecialized common ancestors. It is

not closer, for instance, than that between the Oligocene Felide and

the modern Cryptoprocta of Madagascar, whose common descent from

an unspecialized placental carnivore (Viverrid or Miacid), analogous to

the marsupial didelphyids, is generally admitted. The common char-

acters distinguishing thylacinids and borhyzenids from the didelphyids

are, without exception, such as would naturally be assumed independently

in adaptation to predaceous terrestrial life and have been so assumed in

numerous independent parallel adaptations of the same sort among

266 ANNALS NEW YORK ACADEMY OF SCIENCES

placental Carnivora. On the other hand, Thylacinus has retained cer-

tain didelphyid characters which are already lost by the most primitive

of the Borhyenide (palatal vacuities, posterior position of the orbits,’®

an external lachrymal duct, double perforation of the basisphenoid),

while in other features (brain development, cursorial specialization, etc. )

it is more progressive. ‘he Borhysnidz are more progressive in the

reduction of the last molar, in the differentiation of enamel from dentine,

less so in the cursorial adaptation of the limbs and feet.

Descent from a common ancestral type is undoubtedly shown, but some

at least of the above differences point back to Didelphyide as this common

type. The characters which Sinclair uses to separate the thylacines are

the reduced number of incisors, the carnassial specialization of the molars

and especially the loss of the metaconid. Every one of these features,

besides numerous other common characters which he does not specify,

may be paralleled in two or more distinct lines of Carnivora whose com-

mon ancestors are not more predaceously specialized than Didelphys.

The loss of the metaconid oceurs in Cyon, Ischyrocyon, Simocyon and

Enhydrocyon among the Canidee, in all the post-Oligocene Felide, in

Gulo, Megalictis, Mustela, etc., among the Mustelide, in the later Hye-

nide, in Hyanodon and Pterodon among the Hyenodontide, in Patrio-

felis among the Oxyzenide, in all the later Mesonychide. Each one of

these genera is independently descended from genera in which the

metaconid is well developed. In every case, it is simply a stage in

predaceous adaptation of the molars, nor can it be assigned any other

significance in the marsupial carnivores. There is, in short, no evidence

for assuming a closer affinity between thylacines and borhyenids than

common descent from didelphyid ancestors, and there is strong evidence

against such an assumption. But if this be true, these animals afford

no evidence for Antarctic connections between the southern continents ;

for we have seen that Didelphyid marsupials were certainly present in

the Mesozoic and early Tertiary of Holarctica and of South America,

and we have no reason to believe that they would have had greater diffi-

culty in reaching Australia in the Mesozoic or early Tertiary than the

murine rodents found at a later date.

The supposed presence of Diprotodont marsupials in the South Ameri-

can Tertiary and in modern Australia has also been used in support of

Antarctic connections between the two continents. The recent mor-

phologic studies of Dederer*® and Broom®® have shown that Cwnolestes

*8 Interpreted by Sinclair as a progressive character in 7hylacinus, but certainly the

reverse in analogous placental adaptations.

7 PAULINE H. DepereR: Amer. Nat., vol. xliii, p. 614. 1909.

sR. Broom: Proc. Linn. Soc. N. S. W., vol. xxxvi, p. 315. 1911.

MATTHEW, CLIMATE AND EVOLUTION 267

is not a true diprotodont, but in fact belongs to the polyprotodont divi-

sion of the Marsupialia, and with this genus must be associated all of the

Epanorthids and probably all of the so-called Paucituberculata of the

South American Tertiaries. If then the Diprotodonta, so dominant and

so widely varied in Australia, were wholly absent from South America,

while parallel adaptations were developed there from the Polyprotodonta,

the distribution of these marsupials affords a valid argument against

instead of for any Antarctic connection during the Tertiary.

In view of the great amount of adaptive divergence seen in the various

Pleistocene and modern genera of Australian Diprotodonta, the origin

of the suborder in Australasia or its earliest invasion of that zoological

region, must be dated far back in the Tertiary. On our present evidence

it may well be regarded as wholly autochthonic, derived from early Ter-

tiary or possibly from late Mesozoic polyprotodonts. Nevertheless, in

view of the defectiveness of the Mesozoic record, where we should chiefly

expect to find this group, if anywhere in the North, and the presumable

‘rarity of Tertiary survivors, there is nothing unlikely in the view that

they originated primarily in the North lke their polyprotodont and

allotherian relatives and were driven southward with the former group

and somewhat more thoroughly extinguished in the north, while in Aus-

tralia they blossomed out into a great adaptive expansion paralleling the

absent ungulate mammals.

It is probable that the opossums survived in North America throughout

the Tertiary, although there is no clear record of them in our Miocene

and Pliocene.*t But we know only a small part of our Pliocene fauna

as yet, and the Miocene, although better known, represents chiefly the

animals of the open plains, the forest fauna being very incompletely rep-

resented. On the other hand, it seems probable that the apparent dis-

appearance of marsupials from Western Europe after the Lower Miocene

was real, and it is probable that they had disappeared even earlier from

Asia. They have not been found in the later Tertiaries of India or

China, so that they must have been rare if not absent at that time. The

Eocene Tertiary of Asia, where they might be expected to be common,

is altogether unknown.*?

81 A very badly preserved skull from the Colorado Miocene and a jaw fragment from

the South Dakota Miocene in the American Museum collections are perhaps marsupials;

but I have never been able to see in either specimen satisfactory proof that they were

so, and have consequently never recorded them.

©The earliest Asiatic Tertiary fauna is that of the Bugti beds of India, lower Bur-

digalian or upper Aquitanian according to Pilgrim, Rec. Geol. Sur. India, vol. SH ie)

pp. 264-326. It is therefore either late Oligocene or early Miocene.

268 ANNALS NEW YORK ACADEMY OF SCIENCES

TABLE XVI.—Distribution of Polyprotodont Marsupials

Neotropical Nearctic | Paleearctic | Ethiopian | Oriental | Australian

Didel phyidee 9 . + 7 NI. as | Lhylacinidse

Recent Ganolestee Didelphys None ‘ None None Dasyuride

Pleistocene | Didelphyidee | Didelphys | None None None peor

Payiee se rab G Dasyuridse

Bore yee = None (Record in-

Pliocene Didelphyidze | ~ ees None eaicnaate None

Epanorthidee say eon ate)

; Borhyzenidee None after

Miocene Didelphyidee ace lower Mi- (No record) | None

Epanorthidee cene 5

is 3

; z

Oligocene Dilelobyide Peratherium| Peratherium| None = a

iS) ‘BS

= QO ~

o ao

mA a

Polydolops, ete aS >, as

Borhyzenidie & 2 eS

Eocene Didelphyidee | Peratherium| Peratherium 3 2 ‘5

Caroloame- = ra S)

aie o =

ghinia = a a

eo y e =

S 3 S

N Cimolestidee} , . . a & =

Cretaceous Thleodon |(N© record) S S

ie g

Proteodidel- 5 S)

Comanche phys * (No record ) 3s 2

= fo

fo} ie)

: : ; Zi Z

Jurassic Triconodontidze ~ 2

53 Fragmentary remains, referred to Hy:enodontide by Dr. Ameghino.

& Jurassic, fide Ameghino.

8 Doubtful fragments of jaws which may be Didelphyid.

86 Hxcept on borders of Australian region.

- MATTHEW, CLIMATE AND EVOLUTION 269

TasLe XVII.—Distribution of Diprotodont and Pseudodiprotodont Marsupials

and Allotheria (Multituberculata)

Peer: Anlothera Di prowsounls

Neotropical | Nearctic Palearctic | Ethiopian Australian

Macropodidee

Recent Cenolestes*" | None None None Phaseolomy-

idee ete.

Diprotodon-

tidee

Pleistocene None None Macropodidee

Thylacole-

onide ete.

Pliocene Spar None None

thidee®

Mi Epanor- N N

iocene thides®® one one

Oligocene as None None None Wynyardia®?

Eocene P Peep : ? None

Paleocene Ptilodus Neoplagiau-

Polymasto- lax

don ete.

Cretaceous Ptilodus

Meniscoes-

sus ete.

Comanche

Jurassic Ctenacodon | Plagiaulax | 7.

ate ae Tritylodon

Triassic Microlestes | Karroomys

87 This genns is a pseudo-diprotodont, as its real affinities are with Polyprotodontia, as

shown by Dederer and Broom, I. c.

88 Affinities probably with Cenolestes.

89 Combines Polyprotodont and Diprotodont characters.

270 ANNALS NEW YORK ACADEMY OF SCIENCES

MONOTREMATA

The monotremes are the lowest group of mammals, far removed struc-

turally from any others. Their connection with the main stock must

date back to the end of the Paleozoic era. Nothing is known of their

evolutionary history. The Multituberculata of the Mesozoic and Basal

Eocene are regarded by Broom as ancestral to them, but this view is not

supported by additional evidence since obtained. Xenotherium®® of the

North American Oligocene, referred by its describer to the monotremes,

is an Insectivore related to the Chrysochloride ; Scotwops** of the South

American Tertiary is an Armadillo,®? and other genera referred by

Ameghino to the Monotremes probably also pertain to other groups.

We find them to-day limited to the Australian region, and surviving

even there only by virtue of unusual specializations of habit; Hchidna

protected by its coat of spines, Ornithorhynchus by its amphibious habitat,

both genera burrowing and nocturnal. Presumably, these genera repre-

sent the last relic of the early Mesozoic dispersal movements of the

Mammalia.

SUMMARY OF THE EVIDENCE FROM DISPERSAL OF LAND MAMMALS

The foregoing review of the several groups of land mammals shows

that the more recently evolved and dominant races of Mammalia are to-

day mainly Holarctic, and many of them have not yet reached the more

peripheral regions; that the ancestry of all these dominant races has been

found in the Holarctic Tertiary formations, sometimes in Europe, some-

times North America, more generally a series in each country of equiva-

lent approximately ancestral stages. Where the geological record is ade-

quate, these races are shown to be newcomers in the peripheral continents

which they have invaded, and any ancestral series is absent. Their repre-

sentatives in the peripheral continents are to a varying degree primitive

and allied to earlier stages in the evolution of the race as represented in

the Tertiary record of Holarctica, but they have specialized more or less

along parallel or divergent lines from the direct line of descent of the

northern representatives.

When the parallel series in Europe and North America are sufficiently

complete they are seen to be not parallel phyla of independent local evo-

lution, but periodically recruited by more progressive new stages, appar-

89 HaARL DouGLass, 1905. (The name is preoccupied by Xenotherium Ameghino, 1904,

a genus of typotberes.)

*1L, AMEGHINO, 1887.

WwW. B. Scorr: Rep. Prin. Exp. Patag., vol. 5, p. 12. 1903.

MATTHEW, CLIMATE AND EVOLUTION yal

ently from a common center of dispersal. The relations are like those of

one side and the other of a branching tree whose trunk region is unknown

to us.

The more ancient and primitive groups of the Mammalia have mostly

disappeared, or are in process of disappearance, from Holarctica. In the

peripheral continents, they have undergone in many cases a notable local

adaptive radiation and expansion, extensive in proportion to the isolation

of these continents from the northern realm, more complete during the

early and middle Tertiary than now. When the reunion to Holarctica

permitted the northern fauna to invade the peripheral continents, these

autochthonous groups were in general unable to maintain themselves

against the competition of the more progressive northern races, and have

either wholly disappeared or left a few scattered survivors, mostly aber-

rant specializations which did not come directly into competition with the

invading races. The survival of the major part of the marsupial radia-

tion in Australia is attributable to its continued isolation. The apparent

fact that Neotropical races of Edentata were able to invade North Amer-

ica during the Pliocene and Pleistocene may be ascribed to two factors:

1) No Nearctic groups of closely analogous specialization existed at

that time.

2) Owing to the far southerly extension of South America, the evolu-

tion of mammals in that region was, so far as controlled by climatic

change, more progressive and more nearly equivalent to the Holarctic

evolution than in Australia or Africa. Its products therefore were better

able to maintain themselves against their northern competitors.

If we regard the Proboscidea as of Ethiopian origin, we must suppose

that they too constitute an exception to the general rule that the races

evolved in the peripheral regions have been unable to invade Holarctica.

But the recent discoveries of Pilgrim and Cooper in the Oligocene of

India tend strongly to show that the Proboscidea were from the first, as

they certainly were in the later Tertiary, a group of Asiatic, not African,

dispersal.

The dominant influence of climate in controlling the range of modern

mammals has been emphasized by C. H. Merriam. The mammals adapted

to north temperate or even boreal climate are the most specialized and

last evolved members of their respective races. The most primitive sur-

vivors of northern races, and surviving members of races formerly abun-

dant in the north, are met with chiefly in tropical regions. Similar rela-

tions are seen in the faunz of the antarctic as compared with the southern

tropical regions, although less obvious. This is especially seen in South

979 ANNALS NEW YORK ACADEMY OF SCIENCES

America. It is displayed there quite as clearly in races, such as the crice-

tine rodents, cervide, etc., which are admittedly of Northern origin, as it

is in any autochthonous groups. Hence, it cannot be attributed to a gen-

eral Antarctic dispersal center, but must be explained as a parallel evolu-

tion under similar climatic stimulus.

The general distribution of Mammalia 6n,these lines is almost univer-

sally accepted; but many writers have pointed out certain supposed ex-

ceptions and found it necessary to account for them by various hypo-

thetical continental bridges. A careful consideration of these supposed

exceptions shows that, if due allowance be made for parallelism and for

the imperfection of the record, each one can be more satisfactorily inter-

preted in accordance with the general law. And the acceptance of any

such continental bridges would entail migrations of other groups which

assuredly have not occurred. The hystricomorph rodents of South Amer-

ica afford a single exceptional instance, in which over-sea transportation

from Africa appears to be the only reasonable interpretation of the evi-

dence at hand.

I place much greater weight on the evidence from mammalian distri-

bution than on that of any other terrestrial group for several reasons, as

follows:

1) Their past history, the time, place and method of evolution of the vari-

ous races, is better known than in any other group of land animals or plants.

2) The complexity of structure in the hard parts which are preserved as

fossils is greater, affording a larger amount of evidence by which we may dis-

tinguish parallel or analogous races and determine the closeness of their real

affinities. As Stehlin® has recently observed, a single tooth of a mammal

affords as much structural evidence whereby to determine its relationships as

the entire skeleton of most invertebrates. Where our evidence is thus lim-

ited (to a single tooth, for example), we may, and frequently do, find difficulty

in deciding the exact aflinities of a fossil mammal. But where we have the

skull or the skeleton or even the entire dentition, the results are correspond-

ingly sure and precise as the data are more extensive.

3) Owing to their nearness to ourselves, their large size and other causes,

we are better able to understand their adaptation and observe and appreciate

the factors which may affect their evolution and migration.

In dealing with the evidence furnished by the lower vertebrates and

invertebrates, we are hampered by the wider limits of time within which

the migration may have taken place, by the relative simplicity of the

_ structure of the hard parts, which makes it less easy to distinguish paral-

®3“ijber die Siiugethiere der Schweizerische Bohnerzformation.” Verh. Schw. Naturf.

Gesell., 98 Jahresvers. 1910, Basel. P. 11 of separate.

MATTHEW, CLIMATE AND EVOLUTION 273:

lelism from immediate affinity,°* by the relative scarcity of fossils as com-

pared with living species (among land animals), and by our less certain

knowledge of the causes which may control their evolution, their means

of migration, and their true evolutionary history and affinities.

INTERPRETATION OF NEGATIVE EVIDENCE IN FOSSIL MAMMAL FAUNA

In considering a Tertiary mammal fauna, we must keep in mind the

facts that there may be large facies of it that are represented imperfectly,

if at all, in our records, and that there may be important parts of it

which have left little or no record, owing to their habitat, small size or

other circumstances. We may, with some reserve, conclude that the en-

tire absence from the record of a group which is abundant in other faune

indicates its real absence from the fauna. But we are not justified in so

concluding in the case of rare or inconspicuous races. It is fair to as-

sume that the absence of. Perissodactyla from the Oligocene fauna of

Egypt or the Miocene fauna of Patagonia was real, and not a matter of

defective record. The same assumption would be unjustified in the case

of didelphid marsupials and dilambdodont Insectivora respectively. But

the most conclusive evidence of the absence of a certain group from a

given fauna is that while it is not found fossil, another group is found to

have become adapted on parallel lines, taking its place in the fauna. The

absence of Perissodactyla and Artiodactyla from the Miocene of South

America is confirmed by our finding Litopterna, Toxodontia and Astra-

potheria, which parallel in adaptation the horses, rhinoceroses, tapirs,

camels, ete., of the North; the absence of Carnivora by the parallel adapta-

tion of marsupials to take their place. The evolution of lemuroid pri-

mates in Madagascar into large quadrupedal forms apparently paralleling

certain groups of Ungulates,*? affords some evidence that the Tertiary

hoofed mammals were unable to invade Madagascar.

The absence of fissiped Carnivora from the recorded Oligocene fauna

of Egypt would not be conclusive in itself; but, coupled with the excep-

tional variety and abundance of the more archaic creodonts of the family

Tt may be noted in illustration of this point that a natural cast of the entire carcass

of a mammal would afford far less secure information as to its real affinities than would

a fossil skull, and less even than a lower jaw with reasonably perfect teeth. The parallel

adaptations so frequently recognized among mammals lead to superficial resemblance of

distantly related types whose true affinities are readily recognized by the internal struc-

ture. If, as among most invertebrates, we had only an external skeleton to guide us,

the real affinities would not be so securely recognized.

% The skull and the short limbs of Megaladapis are very suggestive of such types as

Promerycocherus. The feet do not, however, indicate a terrestrial habitat, nor are the

teeth efficient in grinding. The resemblance in teeth and skull of Archeolemur to the

Anthropoidea is very marked.

a4. ANNALS NEW YORK ACADEMY OF SCIENCES

Hyzenodontide, it is very strong evidence that fissiped Carnivora had not

y , af g

yet invaded the Ethiopian region, at least in any considerable numbers.

DISPERSAL OF REPTILIA

The essential adaptive feature which distinguishes mammals and birds

from the reptiles out of which they arose lies in the non-conducting cov-

ering to the skin,—of hair or fur among mammals, of feathers among

birds. The assumption of this covering enabled the body to be kept at a

uniformly high temperature, thus favoring the maximum of bodily activ-

ity, and making it practicable to develop the circulation and the entire

organization to a much higher standard. It also made these classes of

animals independent of the temperature of their environment. It ena-

bled them to withstand cold or variable climate and to take full advantage

of the conditions of the colder regions, which appear to favor a higher

development than can be attained in moist tropical countries.

The initial development of mammals and birds took place, so far as we

are able to judge, during the great arid period of the Permian-Triassic.

They appear to have been derived from unknown groups allied respec-

tively to the theromorphous reptiles and to the ornithischian dinosaurs.

We know almost nothing of their Mesozoic evolution, because the upland

epicontinental formations of the Mesozoic, in which this record should be

chiefly preserved, have been totally swept away, or if any remnants re-

main, they have not been recognized and sufficiently explored to recover

it. The formations of the swamps and coastal marshes, river-deltas, lit-

toral regions and shallow seas of the Mesozoic are extensively preserved

and their inhabitants well known to us. But of the upland fauna, we get

only an occasional glimpse in such deposits as those of Solenhofen, where

a few remnants of the fauna of the adjoining uplands have been pre-

served in great perfection. We have, indeed, indirect evidence as to the

nature of the upland fauna of the Mesozoic, for the successive groups of

swamp dinosaurs, the marine birds and pterodactyls of the later Mesozoic

and the abundant and varied mammalian fauna which appears at the

beginning of the Tertiary are not derivable, any of them, from their

predecessors in the swamp or marine faunz, but must be traced back to

ancestors distinctly adapted to dry-land life, which reinvaded the coast-

swamp, littoral or marine provinces. ‘This will appear more in detail in

the discussion of the several orders. The point here to be emphasized is

that the dry-land vertebrate fauna has been throughout the dominant

facies and has repeatedly reinvaded the swamp and sea-coast provinces,

the higher activity and better organization acquired on land giving its

MATTHEW, CLIMATE AND EVOLUTION

-~2

members, when readapted to the marsh or littoral conditions, an advan-

tage which enabled them to supersede the autochthonous dwellers in those

conditions. Per contra, there have not been a succession of invasions of

the dry land by the vertebrate inhabitants of swamp and sea-coast. Once

established on dry land, the primary groups of dry-land reptiles held

their own and evolved and expanded into higher types and greater variety,

but they were not recruited, so far as the evidence shows, by new invasions

from the swamp and aquatic fauna.

DINOSAURIA

The dinosaurs appear to be primarily a dry-land adaptation (properly

speaking, two distinct but parallel adaptations) of the primitive rep-

tiles.°° Their most obvious adaptive characters lhe in the long limbs and

swift-running gait and the general parallelism to the ratite birds. As

such, the conditions of life would tend to greater activity and higher de-

velopment and enable them, when they reinvaded the swamps during the

epochs of great swamp-extension, to reach greater size and dominance.

It is these readaptions that are chiefly known to us and are apt to give

the idea that the dinosaurs were distinguished by gigantic size and mass-

ive proportions. In fact, these are no more typical of the order as such

than the whale, hippopotamus and elephant are fairly typical of the

mammals as such. There must have been multitudes of small dinosaurs,

mostly inhabiting the upland, a smaller number living among the swamps

and marshes, but we know comparatively little about them. Some notion

of their numbers and variety in the Triassic is gained from the innumer-

able footprints spread over the Triassic shore-deposits of the Connecticut

River. But of all this multitude, we have actual remains of only two or

three types. The Compsognathus skeleton of Solenhofen is, perhaps, an

example of the small lght-limbed upland dinosaurs of the Jurassic ;

Hallopus and Podokesaurus are perhaps fairly representative of their

Triassic ancestors. The Jurassic sauropods, while highly specialized for

aquatic hfe and river-bottom wading, yet retain a few features indicative

of former land life. One of these is the long limbs, which it would seem

must have been acquired on land. Another is the fact that the knee bends

forward as it does in all other dinosaurs, while in reptiles primarily am-

phibious the knee bends outward and the limbs are short. The elbow of

the Sauropoda, on the other hand, bends outward, as in reptiles generally,

not backward, as it does in primarily quadrupedal land animals, and this

6H. VON HUENE: Geol. u. Pal. Abh., N. F., Bd. xiii, s. 22-38. 1914; Neues Jahrb.,

Beil. Bd. xxxvii, s. 577-587. 1914. :

276 ANNALS NEW YORK ACADEMY OF SCIENCES

I take to be an indication that their quadrupedal gait is partly secondary

and that they are derivable from long-limbed, partly bipedal ancestry.

The shortening of the feet and pillar-like construction of the limbs is an

obvious parallelism with the specialization of these parts seen in all large

land mammals and is an adaptation to their great size. No near parallel

can be found to this group among living animals; the hippopotamus

affords some suggestions, but diverges widely in many respects.**

I have already referred to the primary adaptation of the dinosaurs

as a dry-land adaptation of the Reptilia. ‘To a limited extent, the mod-

ern lizards represent a corresponding adaptation but not carried so far

or occupying so important a place in the fauna. The lizards have to

compete with the large and varied dry-land fauna of mammals, and rela-

tively to these, they occupy but an unimportant niche in the terrestrial

life. They suggest, however, the sort of animal which in the absence

of a higher competing type evolved into the dinosaurs, and their more

specialized types (e. g., Chlamydosaurus) mimic them in proportions in

a most instructive manner.

Dinosaurs are first recorded from the Triassic; those which we actually

know®® are of moderate to large size, slender and long limbed as com-

pared with other reptiles, not highly specialized in dentition, unarmored

and some but not all bipedal in gait. Indirect evidence in the multitudes

See W. D. MattHrew: “The Pose of the Sauropodous Dinosaurs,” Amer. Nat., vol.

xliv, pp. 547-560. 1910.

®§The principal references on ‘Triassic dinosaurs are the following :

R. Broom: “On the South African Dinosaur Hortalotarsus,” Trans. S. Afr. Phil. Soce.,

vol. xvi, pp. 201-204. 1906.

E. Fraas: “Die neuesten Dinosaurierfunde in der schwabischen Trias,’ Die Natur-

wissenschaften, Bd. I, Heft 45, pp. 1097-1100. 1913.

F. voN HuENE: “Die Dinosaurier der europiischen Triasformation.” Geol. u. Pal.

Abh., Supplem. Bd. I. 1908.

———: “Hin primitiver Dinosaurier aus Elgin,’ Geol. u. Pal. Abh., Bd. xiv (N. S.,

Bd. x) Heft. I. 1910.

: “Beitriige zur Geschichte der Archosaurier,’ ibid., Bd. xvii (N. S., Bd. xiii)

vente) eb OWa:

: “Ueber die Zweist’ammigkeit der Dinosaurier,”” Neues Jahrb. Beil., Bd. xxxvii,

s. 577-589. 1914.

Bh. voN HUENE und R. 8. LuLL: “Neubeschreibung des Originals von Nunosaurus agilis

Marsh,’ Neues Jahrb., Bd. I, s. 184-144. 1908.

——— ——: “On the Triassic Reptile Hallopus victor Marsh,’’ Amer. Jour. Sci.,

vol. xxv, pp. 113-118. 1908.

O. JAEKEL: “Ueber die Wirbethierfunde in der Oberen Trias von Halberstadt,’ Pale-

ont. Zeitsch., Bd. I, s. 155. 1913.

R. S. LuLu: “Fossil Footprints of the Jura-Trias of North America,’ Mem.. Boston

Soc. Nat. Hist., vol. v, pp. 461-557. 1904.

———: “Dinosaurian Distribution,” Am. Jour. Sci., vol. xxix, pp. 1-39. 1910.

——: “The Life of the Connecticut Trias,” ibid., vol. xxxiii, pp. 397-422. 1912.

O. C. MarsH: ‘Notes on Triassic Dinosauria,” ibid., vol. xliii, pp. 543-546. 1892.

———: “Restoration of Anchisaurus,” ibid., vol. xlv, pp. 169-170. 1893.

: “Dinosaurs of North America,” U. 8. Geol. Sur., 16th Annual Report, pp. 143-

244, pill. 1896.

MATTHEW, CLIMATE AND EVOLUTION ony

of footprints of the Connecticut Valley sandstones shows that there must

have been also a great number and variety of small bipedal three-toed

forms all presumably dinosaurs, and other reptiles with shorter feet and

more numerous toes which may also have been dinosaurs, although not

generally so referred. Liull** states in regard to the latter: “These forms

seem to represent survivors of the ancient stem from which the dinosaurs

arose; they may, however, represent primitive quadrupedal dinosaurs

which had not yet acquired the erect gait.” He calls attention to their

possible relationship to Protorosaurus and Kadaliosaurus.

From these and other fragments of evidence, we may reconstruct a

concept of the dinosaurs as a land adaptation developed during the arid

Permo-Triassic climatic phase, corresponding to the later deployments of

the mammals along the same lines of adaptation and under a similar

impelling cause of progressive aridity and continental expansion. Dur-

ing the base-leveling and submergence and moist tropical climate of the

Jura, these dry-land adaptations reinvaded the swamps and _ coast-

marshes, the least specialized types (cf. Protorosaurus), more quad-

rupedal and some of them long-necked, reverting farthest towards an

aquatic life and specializing into the peculiar Sauropoda, while the higher

bipedal types retained more of their terrestrial habitat but evolved into

huge, massive armored and bizarre creatures, to be paralleled in habit

and type at a later date by the bizarre specializations of the Eocene Mam-

malia. These are the familiar dinosaur fauna of the Upper Jura and

basal Cretaceous. The drier uplands of that time must have been ten-

anted by lighter, smaller dinosaurs, but of these, in my opinion, we have

little direct evidence. But that they continued to exist and carry for-

ward their primary lines of adaptation is shown by the subsequent history

of the order.1”°

In the Lower Cretaceous occurred a swing towards emergence and arid

conditions, not extreme, but sufficient to wipe out the sauropod dinosaurs

in the northern world. They survived, however, in the southern conti-

nents until, in the middle and later Cretaceous, the pendulum swung back

to a marked extreme of submergence and moist-tropical climate, and

their remains are found in late Cretaceous beds in South America, East

Africa, Madagascar and Australia. The correlation of these beds is in

need of revision, however; they may be Comanchean. In the Northern

CONES Se bovis Ber ose jo, Zhe | aityay

oR, S. LuLy (“Dinosaurian Distribution,” Amer. Jour. Sci., vol. xxix, pp. 1-39, 1910)

has admirably summed up the data regarding the geological occurrence of dinosaurs.

While not agreeing in all respects with his interpretation, I take pleasure in noting the

accuracy and clear presentation of the evidence as worthy of the high regard in which

its author is held by his confréres. :

978 ANNALS NEW YORK ACADEMY OF SCIENCES

world, at all events, they did not reappear after the early Comanchean.

A dinosaur fauna largely similar to that of the Jurassic in habits and

adaptation in other respects, developed during the late Cretaceous in

the North. It contains no Sauropoda, but it includes amphibious types

(Trachodontide) with marked aquatic adaptation, gigantic terrestrial

swamp and forest dwellers, like the ceratopsians, tyrannosaurs and anky-

losaurs, and many smaller more agile forms. These Cretaceous giants,

however, appear to have evolved, not from amphibious or aquatic dino-

saurs of the Jura, but, in part at least, from small and little known forms,

of more upland adaptation, which had been much more highly specialized

for dry-land life than any of the Jurassic swamp dwellers, and had re-

adapted themselves to the forest and swamp environment of the later

Cretaceous. The trachodonts and ceratopsians, for instance, while re-

lated to the earlier iguanodonts, cannot be directly derived from them

but must be traced back to some unknown contemporary which was highly

progressive in developing efficient grinding dentition, compact feet with

flattened hoofs, ete.—characters which in a survey of mammalian adapta-

tion we find to be especially associated with upland habitat. The evi-

dences of former dry-land adaptation are not so clearly shown in the

other swamp-giants of the late Cretaceous, but they may perhaps be

shown by further study."

In sum, we may find in the hypothesis of recurrent climatic change,

and in the primary adaptation of the dinosaurs as a dry-land adaptation

of Reptilia and their secondary readaptations to forest and swamp life,

a fairly satisfactory solution of their distribution and phylogeny. Lull,

in his able discussion of the subject (1910), explains their adaptation

along these lines. But at present our data, both of correlation and

identification, are too uncertain to allow of positive and detailed con-

clusions in regard to the centers of dispersal and course of migration of

the dinosaurs. That the sauropods survived in the southern continents

long after their extinction in the north appears proven, if we accept the

stated geological correlations of the southern formations where they are

found and set aside as an erroneous identification the reported occurrence

of a sauropod in the Danian of France.’°? That the Theropoda survived

into the Eocene in South America and Theropoda and Predentata into

the Paleocene in North America is not improbable on a priori grounds,

10. J,, DOLLO (Bull. Soc. Belg. Géol., xix, p. 441. 1905) has shown that the quadrupedal

gait of many of the Predentate dinosaurs is a secondary adaptation from bipedal ances-

try. I believe this to be true, to a less extent, of the Sauropoda as well.

102, Nopsca (Rep. Geol. Mag., vol. vii, p. 261. 1910) states that the femur on

which this recorded occurrence is based is not a sauropod but a trachodont dinosaur,

allied to or identical with Telmatosaurus of the Gosau beds of Austria.

MATTHEW, CLIMATE AND EVOLUTION 279

but the evidence that they actually did so survive is open to serious

question. So far as they go, the facts accord with the dispersal of the

dinosaurs from the northern land mass. And so far as I have been able

to review the data, the migrations of the order could be made to conform

with the present distribution of continental and abyssal areas (Mada-

gascar excepted'™) about as well as with the different distribution upon

which they are plotted by Dr. Lull.

It is significant in this connection to note that young individuals are

very rarely found in the dinosaur formations. ‘Thousands of individuals

are found together in some of the great quarries, pertaining to a great

number and variety of genera and with a wide range in size, but it is

very rare to find young individuals among them. This fact is well known

to collectors, but has not, as far as I know, been commented upon in

print. It is true that young individuals are less clearly distinguished

from adult among reptiles than among mammals, the chief difference

being the imperfect ossification of the bone structure, and that such im-

perfectly ossified bones are likely to be poorly preserved and might often

be rejected by collectors on this account. But making all reasonable

allowance for these considerations, there remains a very notable contrast

with fossil mammal quarries and fossiliferous formations, in which young

individuals are always to be found among any considerable number of

adult specimens and often are more numerous than mature individuals.

This may be interpreted in conformity with the above theories as to

the habitat of dinosaurs, by supposing that the young dinosaurs were

more dry land or upland animals, retaining the ancestral habitat, and

coming down into the swamps only when they reached maturity and

their larger size made an amphibious or aquatic habitat more suitable.

The young animals would rarely or never visit the swamps and deltas,

whose formations have alone been preserved, and their fossil remains

would be correspondingly scarce.

Young crocodiles, so far as I can gather from various descriptions, are

somewhat more terrestrial in habit than the full-grown animal, but the

difference is evidently not considerable. Analogous cases among fish,

marine types breeding in fresh water and vice versa, are well known.

The migration of birds has also some analogy, if, as may often have been

the case, the swamp dinosaurs resorted to dry land for breeding and egg-

laying purposes. In either case the breeding or egg-laying place would

be presumptively the ancestral habitat of the race.

103 The Cretaceous sauropoda of Madagascar may have reached that island in the same

Manner as the hippopotamus did at a later period, namely by swimming.

280 ANNALS NEW YORK ACADEMY OF SCIENCES

CHELONIA

The publication of Dr. Hay’s splendid monograph’** upon the extinct

Chelonia of North America has added a great deal to the available data

for explaining the distribution of this group. So far as the Tertiary

and modern distribution goes, it conforms to the same lines of dispersal

as do the various orders of mammals. The pre-Tertiary history of the

order is mostly too fragmentary to afford any important data bearing,

pro or con, upon the theories here presented. The whole order is in

general conservative and persistent to a high degree, like the Crocodilia.

The occurrence of giant tortoises (Testudo) on several oceanic islands

and in Australia and Patagonia (Metolania) has been adduced as evi-

dence for continental connection of these islands and for an Antarctic

connection of the two southern continents. Here, as in the case of the

carnivorous marsupials cited on page 265, the evidence will not bear close

examination. In the first place, we know that large tortoises of the

genera Testudo and Stylemys are among the most abundant fossils in

the Middle and later Tertiary of the Nearctic, Palearctic, Oriental and

Ethiopian regions. So far as we can judge, they were cosmopolitan,

except Australia and Patagonia. They occur in the Pleistocene of Cuba

and Madagascar and survive to the present day in certain islands in the

Indian Ocean and in the Galapagos Islands. So far as these oceanic

islands are concerned, if we assume that their presence in one involves

continental union, it must do so in all. If such continental union oc-

eurred, it is hardly conceivable that, in each instance, tortoises alone

would have made their way to the islands. We must infer for each and

every one of them a vertebrate and invertebrate land fauna. Where is

that land fauna, and why has it perished? The idea of selective drown-

ing might possibly be entertained if we had to do with only a single

instance, but is too absurd for serious consideration, when we deal with

several instances of the survival of the same race. The only reasonable

method of accounting for the presence of Testudo on these islands is

that its facilities for oceanic distribution are somewhat better than those

of mammals and that it arrived by over-sea transportation.

The most recent argument for land connection of the Galapagos

Islands is by Dr. Hay.?°° He advocates a connection with Central Amer-

ica, via a submerged ridge which is shown in the reports of the Blake

Expedition to extend southwest from Costa Rica towards the islands.

14 QO. P. Hay: “Fossil Turtles of North America,’ Carnegie Institution Publ. No. 75.

1908.

1061 OSE. EUAN, 1G.

MATTHEW, CLIMATE AND EVOLUTION 281

The depth of this ridge Dr. Hay omits to state, but the soundings indi-

cate it as being upwards of ten thousand feet, so that it does not mate-

rially affect the improbability of an elevation to this extent. The Gala-

pagos Islands are purely volcanic in origin and stand upon a platform

less than a thousand feet in depth, similar on a smaller scale to that

which surrounds the continents and presumably open to similar inter-

pretation. If so, the islands have, probably, been more or less completely

united at periods of continental emergence and completely isolated at

periods of continental submergence (if any such haye occurred since

they were first upbuilt from the ocean floor by voleanic ejectamenta)

but never connected with the mainland. As the island platform is less

extensive than Madagascar or Cuba, farther from the mainland and

without intervening island stepping-stones, the opportunities for success-

ful colonization through rafts or other means of transport have been

fewer, and have not succeeded in introducing any mammals or amphib-

ians and but few reptiles and invertebrates. The most favorable oppor-

tunity for such colonization would be when the islands were at their

maximum elevation—towards the end of the Tertiary, if this corre-

sponded with the elevation of the mainland—as at that time the extent

of coast and consequent probability of making a landing would be much

greater. The subsequent isolation of the islands by submergence ac-

counts for the presence of distinct although related species on different

islands. Thus the series of “miracles of transportation,” which Dr. Hay

finds it so difficult to accept, dwindles down to a single “miracle” and

to one which he must invoke to account for the populating of the more

remote Pacific islands, and which, when considered in relation to the

time involved, does not really involve any serious improbability. On

the other hand, if a miracle be an exceptional occurrence in apparent

contravention of all probabilities, and without assignable causes in nat-

ural law, I think the processes of selective drowning, or of selective

migration of sporadic elements of a fauna, involved in the alternate

hypothesis, in addition to the elevation during the late Tertiary of

abyssal depths to the surface, unwarranted by any valid evidence, does

involve a series of miracles, almost as unworthy of belief on the evidence

offered, as the special creation of the species of the Galapagos Islands

appeared to Darwin.

The present distribution of species of Testudo on the islands of the

Indian Ocean has been partly changed by man, so that there is some

uncertainty about its details. Lydekker states it as follows:

“Madagascar, probably the Comoros, North and South Aldabra—small islands

lying to the northwest of the northern point of Madagascar—the Mascarenes

YR ANNALS NEW YORK ACADEMY OF SCIENCES

HOM

or Mascarenhas, situated to the east of Madagascar and including Réunion,

Mauritius and Rodriguez and lastly the Amirantes and the Seychelles, which

are the most northern of the whole assemblage and only about four degrees

south of the equator.” °°

Jach of these groups of islands, except the Mascarenes, stands upon

a shallow platform, and is surrounded by abyssal ocean, upwards of 5000

feet between the Comoros and Africa, elsewhere upwards of ten thousand

feet. The three Mascarene islands rise separately from abyssal depths.

Madagascar is about 180 miles from the African coast; the other islands

are 400 to 600 miles from Madagascar; the present normal set of current

is unfavorable to transportation from Madagascar.

It is very frequently asserted that a bank of shallow soundings con-

nects India with Madagascar through the Amirante Seychelles group,

and that this indicates a former continental bridge of which these islands

are remnants. The facts are as above stated; the so-called bank is very

little above the general level of the floor of the Indian Ocean and is not

differentiated from it in any features of relief that would suggest its

former continental character.

The transportation of natural rafts five hundred miles against the

normal set of current—or five times that distance if from the East

Indies—is the most improbable element in this explanation. There is

no valid reason to suppose that the general direction of winds and cur-

rents differed materially in the later Tertiary from the present day

conditions. I do not think it necessary to assume with Dr. Lydekker

that the tortoises were of gigantic size when they reached the islands or

to ignore, as he does, the elements of parallelism in considering their

affinities to continental species. Nor does it appear that the difficulties

which he admits in accounting, on the hypothesis of former continental

union, for the absence of the rest of the fauna, should be ‘‘set aside for

future consideration.” They add so greatly to the improbability of the

hypothesis, that in conjunction with the physiographic difficulties it

appears wholly out of range of reasonable probability. On the other

hand, an investigation of the very variable direction of the winds and

currents in the Indian Ocean would probably yield data to reduce the

improbabilities in the hypothesis of over-sea transportation as above

stated. The third possible hypothesis is that the present distribution is

due in part to human agency, not necessarily limited to the historic

period. If this factor may account for a species of Canis in Australia

distinct from the living species of Arctogea, it may perhaps help to

account for peculiar species of tortoises as well.

106 Science Progress, October, 1910, p. 303.

MATTHEW, CLIMATE AND EVOLUTION 983

As for Miolania, it occurs in the Notostylops Beds of Patagonia and in

the Pleistocene of Australia. The Notostylops Beds are Kocene, as here

advocated. The persistence of so highly specialized a genus for so long a

period appears surprising; if they are Lower Cretaceous, as Ameghino

asserts, it is quite unprecedented. My acquaintance with chelonian anat-

omy is not adequate to warrant my venturing an opinion as to how far

parallel evolution from less specialized Pleurodira might account for this

anomaly. But we certainly do not know to what extent this genus or a

less specialized pleurodiran ancestor may have been aquatic or even ma-

rine in its habits. And unless we suppose that it had some such semi-

marine adaptations which would enable it to cross a marine barrier im-

possible for terrestrial mammals, I do not see how to account for its reach-

ing Australia without any of the Notostylops mammalian fauna accom-

panying it. We cannot believe that a placental fauna ever reached Aus-

tralia, for if it had we should not see the development of a marsupial

fauna on analogous adaptive lines to take its place. Miolania, then, could

cross some barrier, presumably an ocean barrier, which land mammals

could not; and it becomes merely a question of how wide a barrier this

extinct chelonian of unknown habits could cross. The present lines of

the continents within the continental shelf would not present materially

greater difficulties in its reaching Australia via Antarctica than Testudo

has managed to surmount in reaching Mauritius and the Seychelles, and

I think we are justified in saying that the occurrence of Miolania has no

weight as evidence of former Antarctic connections of the Southern conti-

nents and, in fact, is opposed to any actual land connection.

The following notes on the distribution of the land Chelonia are sum-

marized from Dr. Hay’s monograph:

Cryptodira are the dominant group of turtles ae compare with the pla-

centals among mammals. All continents except Australia.

Chelydride.—Central America, eastern North America and New Guinea.

Apparently a relict-distribution, but the family is unknown fossil.

Dermatemydide.—Part of Central America. Found in abundance in North

America in the Upper Cretaceous and in reduced numbers during the Tertiary.

Emydide—Chiefly Holarctiec and Oriental. A few have reached South

America, none in Ethiopia, Madagascar or Australia. First known in Holarctic

Lower Eocene.

Testudinide—Very abundant in Tertiary Holarctica but now mostly re-

stricted to its southern margin. Abundant now in Ethiopia and a few species

in Neotropical and Oriental regions; also in oceanic islands. Present in Su-

matra, absent in Java, present in Celebes but absent in Borneo. These and

other features are very suggestive of man’s having had much to do with the

local extinction of Tortoises. For obvious reasons this family would be pecu-

liarly subject to his ravages.

284 ANNALS NEW YORK ACADEMY OF SCIENCES

Pleurodira.—Now limited to the three southern continents, Holarctic in the

later Mesozoic and early Tertiary, and the extinct Amphichelydia from which

they are descended were likewise a Holarctic group. The occurrence of closely

related genera in South America and Madagascar is used in support of a

Brazilian-Ethiopian-Malagasy land connection. It would be interpreted in

conformity with the views here advocated, as due to common descent or to

parallel evolution from Tertiary Pleurodira of Holarctica.

Trionychide.—The distribution of this group is exceptional in that it is en-

tirely absent from the Neotropical region and the Pacific coast of North

America, while common to eastern North America, the Ethiopian, Oriental and

southeastern Palearctic regions and New Guinea. Ameghino records Triony7r

from the Notostylops Beds of Patagonia,” indicating if the identification be

correct that the group was formerly present in South America. It is found

abundantly in the Cretaceous and Tertiary of North America and in the older

Tertiary of Europe; absent from Australia and Madagascar.

Presumably this is a relict-distribution of an ancient group, whose facilities

for transportation were relatively limited. It should be noted that the hy-

pothesis of over-sea transportation on rafts would be less applicable to aquatic

animals than to their terrestrial relatives, as they would be less likely to be

earried out to sea on floating vegetation, on account of their ability to leave

it at will for the shore. But the absence of the group from the Neotropical

and Western Nearctic, and its presence in New Guinea, are anomalous features.

CROCODILIA

The crocodiles are usually regarded as the most conservative of the

reptilian orders. This is true enough, so far as adaptive specialization

from the primitive amphibious environment into the higher plane of ter-

restrial habitat is concerned. Their expansional tendencies have been in

the other direction, towards invasion of the marine province.

The present geographic distribution of the group is as follows:

Narrow | Gavialis, India.

snouted | Tomistoma, East Indies.

Alligator, Southern United States, China.

Broad Crocodilus, Africa, southwest Asia, Oriental and northern Austra-

lian regions, tropical America and West Indies.

snouted

Caiman, Tropical America.

Osteolemus, West Africa.

This is very clearly a remnant-distribution and is explained, at least in

part, by the occurrence of crocodiles in the Tertiary. Fossil Crocodilia

are abundant in the early Tertiaries of Europe and North America. The

Kuropean species, according to Zittel,'°’ belong partly to Crocodilus,

17 WL. AMEGHINO: “Age des Formations Sedimentaires de Patagonie,’ Anal. Soe.

Cient. Argent., tom. L, Liv, p. 52 of separata. 1903.

108 K, A. VON ZITTEL: Grundziige der Palwontologie, 2e Aufl., ii Abteil., s. 272. 1911.

MATTHEW, CLIMATE AND EVOLUTION 285

partly to the extinct genus Diplocynodon, in which the proportions of the

skull are like Alligator, but with a notch for the lower canine, like Croco-

dilus, while the armor, especially the belly armor, is like that of Caiman.

North American Tertiary Crocodilia are all with one exception referred

to Crocodilus, but the armor is incompletely known, and they may prove

also to include Diplocynodon. Gavialis is recorded from the late Tertiary

of India; Tomistoma and Crocodilus occur in the Oligocene of Egypt

and Tomistoma in the Miocene of southern Europe. The common Egyp-

“fy Alligators

WY Crocodiles Eee a

ILI] Calmans VA Crocodiles

tn late Crelaceous

and early Tertiary __

Osleolaemu

Fic. 32.—Distribution of the Crocodilide

Originating probably in Cretaceous Holarctica, they have been restricted to the pe-

ripheral continents by inability to become adapted to cold climates. Note discontinuous

occurrence of crocodiles and of alligators, the last the most specialized, as Caiman and

Osteolemus are the most primitive of the living genera.

tian Oligocene species of Tomistoma is intermediate between this genus

and Gavialis.

The Upper Cretaceous crocodiles are nearly allied to those of the early

Tertiary.

The Jurassic and Comanchiec crocodiles include also long-snouted

gavial-like forms, more or less marine in habitat, and broader-snouted

crocodile or alligator-like forms of more strictly fresh-water habitat. All

286 ANNALS NEW YORK ACADEMY OF SCIENCES

have amphiccelous vertebrae, whereas all Cenozoic and late Cretacie croco-

diles have proceelous vertebra. It is commonly believed that certain of

the narrow-snouted types (Teleosaurus) led into the gavials, the broad-

snouted (Goniopholids) into crocodiles and alligators: and that the

broad-snouted types first appearing in the Upper Jura are derived from

the teleosaurs which first appear in thesMiddle Jura. Neither of these

propositions seems to me to be probable. 'The narrow-snouted crocodiles

are characteristic of marine or semi-marine formations, the broad-snouted

kinds of fresh-water formations; the known formations of the Middle

Jurassic are chiefly marine, those of the Upper Jura chiefly fresh-water.

If we turn back to the Trias, we find that in the allied Parasuchia

there were also long-snouted (Mystriosuchus and Rutiodon) and broader-

snouted (Belodon) types—both of fresh-water habitat, but apparently

less aquatic than Crocodilia; in the alhed Pseudosuchia the snout was

short, and the adaptation to amphibious or fresh-water life; while the

more distantly related dinosaurs were terrestrial and_short-snouted.

Upon these data, it appears to me more reasonable to suppose that the

Triassic Mystriosuchus and Rutiodon, the Jurassic Geosauride, Teleo-

sauride and Metriorhynchide and the Tertiary Gavialide are all inde-

pendent successive adaptations to a fish-eating diet and a more or less

marine habitat and that the Jurassic Goniopholide are the source of all

the modern Crocodilia. This will also relieve us from the necessity of

supposing that proccelous vertebra and a number of other identical char-

acters were independently and simultaneously acquired in two phyla of

diverging adaptation. 'The accepted view involves the anomaly of asso-

ciating divergent adaptation with convergent structural evolution.

However this may be, we are justified in assuming certain characters

as primitive among the modern Crocodila, since they are common to all

the older types. These are the following:

1) More complete and consolidated ventral armature. Common to all the

Mesozoic genera, retained in Diplocynodon of the European Tertiary and the

modern Caiman and Osteolemus.

2) A notch instead of a pit in the upper jaw for reception of the lower

canine. Common to all the short-snouted crocodiles of the Mesozoic and Ter-

tiary, retained in the modern Crocodilus.

3) Amphiccelous vertebre. Common to all Crocodilia and related groups up

to the middle Cretaceous, lost in most Upper Cretaceous and all Tertiary’”

and modern genera.

4) Large supratemporal and small lateral temporal fenestrie. The upper

temporal fenestra is large in all Mesozoic Crocodilia, considerably smaller in

the gavials, quite small in Crocodilus, Alligator and Caiman.

109 Except Notosuchus of the Patagonian Eocene.

MATTHEW, CLIMATE AND EVOLUTION 287

5) Posterior nares more anterior in position. In the Mesozoic crocodiles,

the choanz are situated at the posterior end of the palatines in the long-

snouted groups, while in the short-snouted Goniopholide, they have moved

further backward, between the palatines and pterygoids. In the modern

Crocodilia, they are still farther backward, entirely enclosed within the ptery-

goids. This is an adaptation to lying submerged with the nostrils only pro-

jecting above the surface of the water and enables the animal to breathe

comfortably in this position. It would naturally develop in the slow, omniy-

orous broad-snouted crocodiles and not in the swift-moving fish-catching, long-

snouted types; hence its greater development in Goniopholide than in teleo-

saurs, ete. The fact that it is fully as much developed in gavials as in croco-

diles is another reason for deriving both from Goniopholid ancestry.

According to the above criteria, Alligator is the most progressive mod-

ern genus.’!° Caiman is primitive in (1); Osteolemus in (1) and (2) ;

Crocodilus in (2) and to some extent in (4); Gavialis and Tomistoma

are primitive in (4), divergent in adaptation in other respects, so that

comparisons would be unprofitable. We may conclude, therefore, that so

far as they go, the Crocodilia accord with the general lines of distribu-

tion of other groups. They ranged much farther north during the Ter-

tiary than they do now; the most progressive modern genus, Alligator,

has the most northerly range, and the Neotropical Caiman, the West

African Osteolemus and the cosmopolitan tropical genus Crocodilus are

primitive in one or another respect. The gavials also had a wider and

more northerly distribution during the Tertiary.

That the present limits of range are conditioned chiefly by tempera-

ture and climate, and that the much wider range in the early Tertiary

was due to a warmer climate towards the poles, will hardly be questioned.

Of previous limitations and expansions of range in the order, due to

previous secular alternations of climate, there is no adequate evidence.

The distribution of the more primitive modern genera in widely sepa-

rated parts of the tropics; the occurrence of the most progressive genus

on the northern borders of the range of the order in two widely separated

regions, and, finally, the survival in the Eocene of Patagonia of a croco-

dile, Notosuchus, of the Mesozoic type which had disappeared from the

Northern world by the Middle Cretaceous,—these facts point to a north-

ern rather than a tropical or southern center of dispersal for the order;

but the evidence is slight and far from conclusive.

10 R, L. Ditmars, of the New York Zoédlogical Park, has observed that crocodiles are

decidedly more active and ferocious animals than alligators. I would not interpret this,

however, as meaning that they are more progressive, in the sense here used, since the

adaptation of the typical Crocodilia is not towards an active life.

288 ANNALS NEW YORK ACADEMY OF SCIENCES

LACERTILIA

Lizards are the largest group of the Reptilia, comprising over 1800

species, mostly of small size. Most of them are active animals, and a

large proportion are adapted to rocky and desert habitat and arid climate.

They are more dependent on external warmth than mammals and birds,

and consequently are excluded from the colder regions; their means of

dispersal are perhaps less limited than with mammals, if we may judge

from their wider distribution, for they do not appear to be of more

ancient origin. Unfortunately, the rarity and fragmentary nature of

their fossil remains stands in marked contrast with those of mammals,

and our evidence as to their evolution and dispersal is chiefly indirect,

based upon the modern distribution, and is neither conclusive nor con-

vineing. Such as it is, it compares fairly well with corresponding dis-

tribution features among the smaller Mammalia and points to the same

conclusions. But it emphasizes the importance of occasional over-sea

transportation as a factor in distribution. Gadow observes? in regard

to the Geckos, the most cosmopolitan of all lizards:

“Although not at all aquatic, they are particularly fit to be transported acci-

dentally on or in the trunks of floating trees, to which they cling firmly, and

they can exist without food for months.”

Other groups are somewhat less easily transported in this way, and to

quote the same authority:

“It is a most suggestive fact that most of those families of Reptiles, and

even of other vertebrates which have a wide distribution and are apparently

debarred from transgressing Wallace’s line, are also absent from Madagascar.”

The iguanas are chiefly Neotropical, but they occur also in Madagascar,

in the Fiji and Friendly Islands and in the West Indies and Galapagos

Islands, as well as on the American continent. Fossil iguanas are re-

corded from the Upper Eocene and Oligocene of Europe and from the

Upper Cretaceous and Middle Kocene of the western States. If these

determinations be correct, they must formerly have been more cosmo-

politan. Their presence in Madagascar is most reasonably explained by

their former presence in Africa, which is rendered probable by the fact

that they occur in the early Tertiary of Holarctica, along with various

mammalian groups which certainly did reach Africa. Their disappear-

ance from the mainland of Africa may be coupled with the invasion of

other later developed groups, Zonuride, Varanide, Lacertide, which

11 HANS Gapow: Cambridge Natural History, vol. viii, Amphibia and Reptiles. 1901.

The distribution data for lizards and amphibians are mostly based upon this authority.

Nid gt

MATTHEW, CLIMATE AND EVOLUTION 289

were prevented from reaching the New World by the absence of any land

bridge or land approximation within their temperature limits. One:

genus of Zonuride has likewise reached Madagascar.

Bearing in mind the progressive limitation of northerly range of the

Lacertilia by the secular refrigeration of the polar regions during the’

Cenozoic, we can see that, if the distribution of land and water has not

greatly changed except within the 600 feet limit, any families arising;

during the middle or later Tertiary would be limited to the old or to the;

new world. While the distribution of various lizards in oceanic islands

compels us to admit that they can cross considerable bodies of water and

obtain a foothold on an imperfectly populated island area, yet the proba-

bilities of their crossing the whole width of a broad ocean and maintain-

ing themselves against competitors trained in the broad arena of a great

continent appear to be very much less and almost negligible. Conversely

then, we may assume that a distribution, such as that of the Scincide,.

Iguanide, Geckonide, Anguide and Amphisbenide, involves the evolu-

tion and cosmopolitan distribution of these families as early as the Ko-.

cene. The Agamide, Varanide, Lacertide, Zonuride, Chameleontide:

are Old World families, and none are known from the New World. The

Zonuride may well be regarded as of Ethiopian evolution; if not, they

must be a remnant of a very ancient stock. The same may be said of the

Chameleons, except that if Ethiopian they reached as far as India.

The Lacertide, the highest, or at least most typical family of lizards, are

evidently the most recent development; they have not yet reached Mada-

gascar or Australia, and their northern limit is higher than in any other

lizards. The Varanide and Agamide have not reached Madagascar but

have spread widely through Australia. The evidence from extinct lizards

is very slight, the remains are scanty and mostly too fragmentary for

positive family identification. Of the several genera from the Hocene

and Oligocene of North America, two are positively referable to the worm-

like Amphisbeenide, whose present distribution in tropical America, the

West Indies and Africa is thus partly explained as a remnant of a former

wider northerly range and presumably Holarctic. Of the remaining

North American Tertiary genera, Peltosaurus and Glyptosaurus are re-

ferred to the Anguide ;* the remaining genera are too fragmentary for

reference or have not been studied.1?

12 WARL DouGLASS: Ann. Carn. Mus., vol. 4, p. 278. 1908.

18 The recorded presence of Iguanidse (Jguanavus) in the Cretaceous and Eocene, while

not provable, is not unlikely ; that of Chameleon (C. pristinus) in the Upper Cretaceous

is improbable and based upon insufficient evidence; the reference of Thinosaurus (Middle

Eocene) to the Varanide appears to be merely a matter of bibliographic convenience ;

the specimens are probably definitely referable, but the only expressed opinion as to

their affinities is by Boulenger (1891), who suggests their relationship to the Telide.

290 ANNALS NEW YORK ACADEMY OF SCIENCES

In general, so far as I can judge, the Lacertilia lend no support to

the theories of transoceanic bridges. Their widespread insular distri-

bution must in some cases, and may in most others, be explained by

over-sea transportation. ‘Chey lend some support to late Tertiary eleva-

tions to the continental shelf line so as to include the continental islands

and to a line of separation in the East Indies which some, but not all,

were able to cross; those which did succeed in crossing it spread widely

through Australia, indicating more continental conditions, and also indi-

cating in these familes a capacity for crossing marine barriers which

enabled some of them to reach Madagascar, New Zealand and various

Pacific islands.

The ratio of their abundance in regional faune is apt to be inversely

to the full development of mammalian life. Where mammals are scanty,

as in oceanic islands, lizards partly take their place; and this is true of

some continental regions as well as of oceanic islands. In the typical

continental fauna, the lizards are largely restricted to desert or rocky

habitat and are of small size. Yet these last are the most typical mem-

bers of the order.. They show what its primary adaptation was. Various

readaptations appear, to fossorial, to aquatic, to arboreal or to terrestrial

forest life, repeated again and again in different families and causing

frequent parallel divergencies from the primary type. This primary

type, I regard as an adaptation to a Mesozoic arid period. The moist

uniform climatic phase of the early Tertiary would tend to develop large

forest living and aquatic forms and restrict and provincialize the more

typical lizards. During the middle and later Tertiary, the typical lizards

would expand and multiply in numbers and variety, but, on account of

their lack of adaptability to cold climate, their evolution was not so

much a successive series of dispersals from a Holarctic center, as a

provincial evolution from the arid centers of the great continents. Such

a priort hypotheses are of little value, however, except as confirmed,

modified or refuted by detailed study of the affinities and geographic

distribution of the genera of each family, checked by a wider knowledge

and more thorough study of the fossil forms. Until the fossil Lacertilia

have been thoroughly studied and their affinities authoritatively esti-

mated, any conclusion whatsoever as to the evolution and distribution of

the order remains highly hypothetical.

Dr. Gadow’s recent study" of the distribution of Cnemidophorus and

its interpretation is an excellent example both of the value of such de-

tailed studies and the need of carefully distinguishing between what the

u4H. Gapow: “A Contribution to the Study of Evolution based upon the Mexican

Species of Onemidophorus,” Proc. Zool. Soc. London, vol. 1, pp. 277-375. 1906.

MATTHEW, CLIMATE AND EVOLUTION 291

data themselves indicate and what is assumed as true from other evidence.

He concludes,—

1) That the species are the product of their environmental conditions;

2) That their dispersal center was in western Mexico, whence they have

spread northeast as far as Texas and Florida, southwardly into South Amer-

ica, northwestwardly into Lower California ;

3) That the primitive type was nearest the Texas and Florida species.

He assumes—evidently on some other grounds—

1) That a great land area stretched out from Mexico far into the Pacific

during the Tertiary all the way between Lower California and Central

America ;

2) That the central tableland of Mexico was a vast fresh-water lake during

most of the Tertiary ;

3) That Cuba was connected with the American mainland during the Oligo-

cene (this assumption underlies the statement that, since the Floridian Cnemi-

dophorus did not reach Cuba, its migration must have occurred as late as

Miocene).

Ortmann,’ reviewing this paper, takes, as proven by Gadow’s studies,

not merely the points actually indicated but also the assumptions which

are entirely unnecessary to explain the data but which Dr. Gadow evi-

dently feels obliged to take for granted. In fact, these assumptions

interfere with a reasonable interpretation rather than help it, and all

of them are questionable, to say the least. The great Tertiary lake is,

I suspect, on all fours with the vast interior “lakes” of the Plains region

of the United States, which the progress of physiographic and paleon-

tologic studies have relegated to the domain of myth. The connection

of Cuba with the mainland of either North or South America inyolves

the same difficulties as the connection of Madagascar with Africa. The

recent discoveries by Dr. de La Torre of a Pleistocene vertebrate fauna

in Cuba strongly confirm this analogy between the Cuban and Malagasy

faune. ‘The existence of extensive land west of the present Pacific coast

line is an equally unnecessary and improbable hypothesis. On the other

hand, Dr. Gadow fails to take into account the barrier between North

and South America which prevented or hindered intercommunication of

land faune during a large part of the Tertiary, while it permitted inter-

communication of marine faune during the Eocene. I am not here

concerned with its nature but may venture to point out that its bearing

on the differentiation of species would be important. For, once across

that barrier, an invading species would find itself in unfamiliar environ-

ment on account of differences in the autochthonic fauna and flora, even

m5 A, BH, ORTMANN: Geog. Jahrb., vol. xxxi, p. 262. 1908.

992 ANNALS NEW YORK ACADEMY OF SCIENCES

though the physical environment were similar. If the rising of the

Mexican tableland conditioned the dispersal of the genus from that

center, we can see in this different biotic environment the reason why

the marginal species in North America should be primitive, while the

marginal species in South America are highly specialized. In general,

it would be true that the species of the dispersal center (or those nearest

to it, where, as in this case, it has become ill adapted for the habitat of the

race) will be the most progressive and those of the marginal areas nearest

the primitive stock. But where the scattering primitive forms, in fol-

lowing the primitive climatic conditions, are brought into a new floral

and faunal environment, this may profoundly modify them and cause a

rapid divergence and specialization.

DISPERSAL OF BrrDs

As a class, birds are extremely difficult in their taxonomy. They are

held closely to type in comparison with mammals, and the differences

between them are mostly directly and obviously due to adaptation.

Adaptive parallelism obscures the true affinities to such an extent that

even at the present day the major classification is somewhat uncertain.

This difficulty is the greater on account of their rarity as fossils. There

is no reason to interpret this rarity as indicating any lack of abundance

of birds in the faune of Tertiary and later Mesozoic time; it is presum-

ably to be accounted for by their generally upland habit, small size and

the lightness and fragility of the skeleton. The small minority of fossil

birds which are known from anything more than a few fragments are,

with two or three notable exceptions, aberrant types—ground-birds,

marine or lacustrine types, whose habitat facilitated their preservation

as fossils. By far the most notable and instructive of these exceptions

is Archaeopteryx.

It has been customary to class the greater number of the ground-birds

(Ratite) as a more primitive sub-class. On @ priori grounds, this may

be correct enough, since it would appear theoretically that feathers must

have preceded flight, the ability to fly being conditioned by high organ-

ization plus small size, and this would involve a rapid circulation and

high temperature, which could hardly be attained without a nonconduct-

ing coating over the body. But it appears certain that most, and possible

that all of the existing ground-birds are readaptations to terrestrial

habitat from flying ancestors, and their resemblances are due almost

wholly to adaptive parallelism.

Owing to their powers of flight, the dispersal of birds is much less

MATTHEW, CLIMATE AND EVOLUTION 293

limited and conditioned by distribution of land and water or by moun-

tain or desert barriers than is that of mammals. Climate and environ-

ment are much more important factors. Their dispersal is accordingly

much wider, and this is especially true of the more migratory and strong-

flying types. The general course of their dispersal from the northern

land masses is in some respects much more obvious than with the Mam-

malia, provided we allow for the extreme imperfection of their geological

record; but on this account, it is not supported by the mass of direct

evidence which we have among mammals.

The most primitive living birds, the penguins, are Antarctic in their

distribution, and as fossils are known only from the Antarctic Tertiaries,

where they include gigantic terrestrial adaptations. It is of interest to

note that the only actually known land vertebrates of the Antarctic con-

tinental area are penguins. If this continent had been united during

the late Mesozoic and early Tertiary to Australia and South America,

we should expect to find a fossil mammal fauna, probably highly pro-

gressive and specialized before the spreading ice swept it out of existence.

We might, indeed, -hope to find a few marine adaptations from this mam-

malian fauna still haunting the edges of the Antarctic pack. But in

fact, the three items which to my mind have a bearing upon early Ter-

tiary conditions in Antarctica all point towards continued isolation and

obviously parallel the fauna of oceanic islands. These are,—

1) Gigantic land-penguins in the ? Eocene deposits of Seymour Island

(also in Patagonia). Compare with the gigantic land birds of various

oceanic islands, correlated with paucity or absence of land mammals.

2) The living marine penguins are not readily interpreted as a pri-

marily marine adaptation, but they are very easy to understand as modi-

fied survivors of a group formerly of terrestrial habits, altered to meet

the present conditions under which alone could life be maintained on

the Antarctic shores.

3) The occurrence of Miolania, as interpreted on page 283, is sug-

gestive of the former presence of giant land-turtles in Antarctica, al-

though not explainable as evidence of former land connections with South

America and Australia.

There may be other indirect evidence in the distribution of marine

Vertebrata and Invertebrata, which, if conservatively interpreted, would

confirm or disprove these indications. So far as they go, they suggest

that ground-birds and land-turtles were the large land vertebrates of

Tertiary Antarctica as in oceanic island faune of to-day.

The distribution of modern land birds is universally interpreted in

294. ANNALS NEW YORK ACADEMY OF SCIENCES

terms of Northern derivation. Oceanic, desert or mountain barriers

have been much less efficient in limiting their range, and the efficiency

of the climatic factor is much more obvious than with mammals. Their

dispersal from a Holarctic center in successive waves of migration is

indicated by the dominantly Holarctic habitat of the highest and latest

developed groups, by the generally tropical habitat of archaic groups

often highly specialized, whose ancestors or relatives are in many cases

known from the Holarctic Tertiary, and by the fact that the southern

continents are peopled, not by a series of dominant groups corresponding

to the Holarctic groups, evolved in a common Antarctic center, but chiefly

by groups of more or less tropical affinities and by a few northern groups

which have crossed the tropic barrier. There are many groups of birds

living to-day in the widely separated tropical regions whose ancestors

have not thus far been discovered in the Holarctic Tertiary. But they

correspond, both in distribution and in relative position in the classifica-

tion, with other groups which the geologic record proves to have origi-

nated by dispersal from Holarctica, and there is no valid reason for

assuming any other origin. The geologic record of Tertiary birds is far

more fragmentary than that of Tertiary mammals and especially in the

Nearctic region.

It should further be observed that the perching birds represent the

primary adaptation from which the various specializations—terrestrial,

wading, marine, etc.—have diverged, and that, in consequence, these

divergently specialized forms retain various archaic features which have

been lost by the central group.

The relations, dispersal and present distribution of birds are thus

wholly in accord with the principles here set forth. The detailed appli-

cation of these principles is beyond the limits of the present discussion.

DISPERSAL OF AMPHIBIA

The modern Amphibia include a few small and for the most part

highly specialized survivors of a group whose period of dominance dates

back to the Paleozoic. Of their Mesozoic and Tertiary ancestry almost

nothing is known. The Stegocephalia, the dominant Amphibia of the

Permian, were far less aberrant and much nearer to the contemporary

primitive Amphibia; their interrelationships are still far from being pre-

cisely definable, and, until these are better understood, it is futile to dis-

cuss the evidence which they may furnish as to former geographic con-

nections.

The distribution of the modern Amphibia is often notably discontinu-

ous, and in the absence of evidence from extinct types as to the real

MATTHEW, CLIMATE AND EVOLUTION 295

origin of these discontinuous distributions they are interpreted by many

authors as affording evidence for various transoceanic bridges. But they

are not essentially different from various instances of discontinuous dis-

tribution among Mammalia, except that they are probably in some cases

of more ancient origin, and are less restricted by ocean barriers.

The urodele Amphibia are Holarctic, save for one family, Plethodon-

tide, which has spread into northern South America and has also reached

Hayti. Although thus limited in dispersal, they would seem to be an

ancient group represented as far back as the Wealden by Hylwobatrachus,

said to be related to the modern Cryptobranchus.*® Their distribution

within Holarctica is more or less of a relict type, broken up by the unfa-

vorable environment of so large a part of this region, especially of the

central portion. The cecilians are tropical but have not reached Aus-

tralasia.

The frogs and toads have a wide dispersal, and so far as a superficial

view may show, the most primitive or archaic families are limited to the

peripheral continents and oceanic islands, while the more progressive

groups are more cosmopolitan, but have not yet reached all of the outly-

ing regions. Some of the families, at least, would appear to be of ancient

origin; Paleobatrachus, allied according to Gadow'** to the Aglossa of

the Ethiopian and Neotropical regions, is recorded from the Jurassic of

Spain, and is said to be common in the older Tertiary of Europe. Among

the modern families the Cystignathide are chiefly Australasian and Neo-

tropical, but a few are still found in North America. This distribution

parallels that of the polyprotodont marsupials, except that the latter have

not reached New Zealand or the Antilles, or entirely disappeared from

the East Indian islands. The Discoglosside inhabit the East Indies and

North America but have disappeared from the intervening portion of

Holarctica; Discoglossus and other genera are found in the Middle Ter-

tiary of Germany. The Pelobatidz stretch across Europe and Asia and

northwestern North America. These three families represent evidently

three successive dispersals.

The other families are more cosmopolitan. The genus Bufo has failed

to reach Australasia, Madagascar or New Zealand, but is replaced in

Australia by a (more primitive?) member of the family. The Hylide

are to-day chiefly South American and Australian, but a few members

still inhabit North America. They are not found in Africa or the Orien-

tal region, where it seems reasonable to suppose that they have been dis-

placed by the true frogs (Ranid), peculiarly varied and abundant in

16. Broiwi, in Zittel’s Grundziige der Paleont., Vertebrata, s. 176. 1911.

iH. (GApow: 1. cs pil45. L900.

296 ANNALS NEW YORK ACADEMY OF SCIENCES

these regions. The Ranide, lke the Bufonide, represent a less ancient

dispersal, probably from a southern Palearctic or Oriental center, since

they have reached northern Australia on one side and northwestern South

America on the other, and, while they have reached Madagascar and the

Solomon Islands, they have failed to reach the Antilles.

These suggested lines of dispersal are based upon the present distribu-

tion interpreted in accord with the principles outlined in previous pages

of this article. While the past history of the Amphibia is too little known

Cyslignalkidde

(scogloss(dae

Pelobatidae

Fic. 38.—Distribution of three families of Anura

These may be interpreted as due to three successive dispersals from the north. The

other families of frogs and toads are more widely spread, and their regional abundance

has conditioned certain peculiarities in the distributions here shown.

to confirm them by adequate direct evidence, I believe that good infer-

ential evidence might be obtained from a comparison of the progressive

or archaic characters of the skeleton in the different families. The fossil

Amphibia afford sufficient evidence to determine the broader lines of their

evolution and differentiation, although they tell very little about their

past distribution. The same conditions hold true with regard to the

fresh-water fishes.

MATTHEW, CLIMATE AND EVOLUTION 297

DISPERSAL OF FRESH-WATER FISHES

The fresh-water fishes afford many striking illustrations of isolated

primitive survivals in the southern continents and especially in their

tropical parts. With marine fishes, the distribution is wider, as we should

expect, and the dominant types are generally world-wide in their distri-

bution. Yet, even with marine fishes, a superficial survey seems to show

the majority of primitive survivals along the southern coasts.

Fishes are, it is to be remembered, dominantly marine. The wider

field and more varied opportunities for development afforded by the

ocean waters, in contrast with the limited and isolated fields and uncer-

tain tenure afforded by fresh-water rivers and lakes, have conditioned

this. The fresh-water habitat for aquatic groups of animals stands in

somewhat the same relative position to the marine habitat as does the

insular to the continental habitat for land animals. It is the refuge for

survivors of primitive faune. And, as in the insular land faune, we are

constantly confronted there with the occurrence in widely remote regions

of archaic types apparently nearly related, whose similarity is partly due

to independent adaptation to a similar environment, partly to persistent

primitivism.

Lepidosiren in tropical South America, Protopterus in tropical Africa,

Ceratodus in tropical Australia are perhaps the most prominent examples

of extremely ancient survivals. These are survivors of early Mesozoic or

even Paleozoic marine and estuarine fishes of world-wide distribution,

and they have endured, in their tropical refuge, the several successive

periods of zonal climate which affected the environment of temperate and

tropical regions.

More pertinent to the problem in hand are the relationships of early

Tertiary fishes of the northern continents to the modern South American,

African (and Australian?) fishes. Here, again, I am compelled to dis-

sent from the interpretations and conclusions of so distinguished an au-

thority as Dr. Eigenmann,"'* who, as it seems to me ignores certain very

important parts of the evidence.

There is a marked similarity between certain parts of the fresh-water

fish faune of South America and of Africa. Higenmann and others

would explain this by a former continental union, but it is certain that

some, at least, of these now tropical types existed in the northern conti-

nents during the early Tertiary. Higenmann’’® asserts, indeed, that no

188 See especially C. H. EIGENMANN: ‘‘Fresh-water Fishes of Patagonia,’’ Reports

Prine. Univ. Exped. Patagonia, vol. iii, parts iii-iv. 1909-10.

19 C, H. EIGENMANN: Popular Science Monthly, 1906, p. 523.

298 ANNALS NEW YORK ACADEMY OF SCIENCES

part of the modern South American fresh-water fish fauna is derived

from North America; but how he reconciles this with the recorded pres-

ence of several of the most typical genera in the Green River Eocene of

Wyoming, I do not see.

A few cases in point may be noted, as follows:

Lepidosteus, now Central American and southern Sonoran. Abundant

in all the Eocene formations of the northwestern States, as also in Europe.

Phractocephalus, Arius, etc., now South American, nearly related to

Rhineastes of the Bridger and Amyzon beds of the western States.

Osteoglossus of Brazil, Borneo and New Zealand, Vastres and Hetero-

tis, also southern types, closely related to Dapedoglossus of the Green

River shales (Kocene).

The characins, which form so important an element of the modern

South American fauna, are, as Eigenmann holds, largely a local expan-

sive radiation conditioned by the immense ramifying river-systems of

that continent. But, considered in their more general relations, they are

a primitive group, the northern cyprinids being a higher and later de-

velopment.

The catfish, which in the North have the characteristics of a disappear-

ing group, are numerous and dominant in South America. Eigenmann

calls attention to the paucity of the Patagonian fauna and its apparent

relations to that of New Zealand and Australia (Galaxiide and Ap-

lochitonide). He does not, however, attach any great weight to this as

evidence for a former Antarctic connection, regarding it as “highly theo-

retical and precarious” so far as the fresh-water fish are concerned—but

“The evidence from other sources of a former land connection has be-

come conclusive.” I might observe here that many students in other

eroups are equally doubtful of the conclusiveness of the evidence for

Antarctic connections in the groups with which they are familiar, while

equally ready to accept as conclusive the evidence in groups with which

they are not familiar.

As regards a connection of tropical Africa with tropical South Amer-

ica, Kigenmann is much more positive, basing it mainly upon the chara-

cins and cichlids, common to both continents. There is no species or

genus common to the two continents. Both families are relatively primi-

tive, as compared with northern related groups. As regards their former

presence in the northern world (which EKigenmann does not allude to) or

their parallel adaptation from marine forms of Cretaceous or early Ter-

tiary time, there is little satisfactory evidence. Nevertheless, the fact

that they represent an adaptive divergence from an intermediate and

more primitive type ancestral to carp and catfish is a suggestive one.

MATTHEW, CLIMATE AND EVOLUTION 299

If now we compare the general relations of tropical fresh-water fishes

with those of the North, it will appear very clearly that the highest and

latest in appearance of the several groups are still limited to the northern

world, and that, in the tropics, more primitive groups exist, many of

them known to be former residents of the northern world, others much

nearer to known or inferred ancestral groups than are any members of

the present northern fish fauna. Where the environment favors, some of

these groups have branched out into an immense variety and number, far

exceeding what is‘known in the colder north. But they are distinctly

less progressive. In the southern continents, we meet with some remark-

able parallelisms to the dominant types of the North, very suggestive at

first of Antarctic connections, but probably explainable (as in Galaaias)

in other ways. ‘These groups impress one as highly progressive, although

less so than the northern groups; but they do not appear to have con-

tributed materially to the tropical faune.

In some respects the fresh-water fishes present nearer analogies to the

birds than to mammals in their distribution; and this is no doubt con-

ditioned by their less strict limitation to land connections for their mi-

gration, and to the greater antiquity of the class.

GENERAL CONSIDERATIONS ON THE DISTRIBUTION OF INVERTEBRATES

AND PLANTS

It would be unwise to attempt any survey of the paleogeographic data

afforded by invertebrates and plants. Lacking both the special knowl-

edge necessary for a critical consideration of the data, and the time neces-

sary to make even an adequate compilation, it would add nothing to the

argument. While, for reasons already given (page 272), placing most

weight on the evidence obtainable from mammals, I fully recognize the

importance and variety of evidence outside the Vertebrata, and the force

which attaches to cumulative evidence from several independent sources.

At the same time I must express a strong conviction that the sources are

not really independent, and that concordant results in several groups

which flatly contradict the results obtained by a study of mammals, can

only indicate one of two things. Either the interpretation of the evi-

dence among the Vertebrata is incorrect or there are factors of error

common to the interpretation of the several other groups which accord

in their disagreement. What these factors may be, I have already indi-

cated and have attempted to show that they account for discordant results

based upon the distribution of the lower vertebrates and interpreted as

involving radical changes between continental and abyssal regions which

300 ANNALS NEW YORK ACADEMY OF SCIENCES

are highly improbable, to say the least, from a geological point of view,

and which are not merely unnecessary but apparently impossible when

we attempt to explain the distribution of the higher vertebrates in accord-

ance with them.

It is true that the evidence against such changes in pre-Tertiary times

is less weighty, and that it diminishes further in the older periods of

geologic time. And the antiquity of many groups of invertebrates,

especially of land invertebrates, makes it impossible to limit the hypo-

thetical land bridges which their distribution is supposed to require, to

the Tertiary or even the Mesozoic. ‘The permanency of the ocean basins

in the older geologic epochs is beyond the limits of this discussion.

So far as a superficial acquaintance shows, the general distributional

relations of most land invertebrata and of plants appear to me to accord

with those of the mammalia. Primitive and archaic’*® types abound

chiefly in the tropics. The most progressive and dominant types are

Holarctic. The southern continents show common groups suggestive of

an Antarctic radiation, but which may, like the marsupials or the chryso-

chloroid insectivores, be remnants of formerly cosmopolitan groups whose

resemblance is due rather to persistence or to parallel evolution under

similar climatic stimulus than to such close affinity as would involve

Antarctic continental connections.

Where, as in the earthworms, we have no knowledge at all of their past

distribution, it is impossible to test this interpretation of their present

distribution ; nor in such a group does it seem possible to estimate how

much and in what manner slow progressive climatic change might affect

their structural evolution, although climatic conditions are evidently

important in controlling their range.

The point that I desire to emphasize is that, if such an interpretation

as I have suggested be possible, it should be accepted in preference to

one which would involve such unexplainable difficulties in the distribu-

tion of the higher animals and such improbable physiographic changes.

No hypothesis can be finally accepted that does not conform to the facts

of distribution in all groups of animals and plants. It is not a matter

of preponderant evidence. Every anomaly must be explained, every dis-

tributional fact must be interpreted in accord with the rest, before we

can consider theories of paleogeography as conclusively proven. It is

not sufficient that the evidence in one group or in ten groups has been

interpreted on concordant lines, so long as there remains an eleventh

group which cannot be so interpreted. But, pending a final agreement

.° Archaic is used in the sense of divergently specialized but little progressive.

MATTHEW, CLIMATE AND EVOLUTION 301

in our deductions from the evidence afforded by the various classes, it

appears to me that we should hold to conservative views rather than

adopt hypotheses of continental relations so much at variance with gen-

erally accepted geological principles and inferences.

To illustrate the point that these discrepancies are a matter rather of

interpretation. than data I may venture to discuss one or two instances

among invertebrates prominently used in paleogeography.

INTERPRETATION OF DISTRIBUTION DATA OF CRAYFISH

I am indebted for my data on this interesting group to Dr. Ortmann’s

valuable discussion of the geographical distribution of fresh-water

Decapoda.**t The interpretation, however, which I would place upon

the facts differs widely from his.

As Professor Huxley has observed, the real difficulty in explaining the

distribution of the crayfish is in their occurrence in the north and south

temperate zones, separated by a wide tropical belt in which none now

occur or are known to have occurred in the past. Two explanations offer

themselves :

1) Independent adaptation from marine types in the northern and

southern hemispheres. This would involve either former Antarctic con-

nections or independent adaptation also of the several southern groups

from marine types.

2) Former cosmopolitan distribution of crayfish, with subsequent dis-

appearance from the tropical belt and differentiation of the isolated south-

ern groups and of the more progressive northern groups.

The latter view is generally accepted, and seems to me more consonant

with the facts of distribution, e. g., presence of crayfish in Madagascar,

while they are absent from South Africa. I am unable to agree with

Dr. Ortmann that crayfish on oceanic islands necessarily involve a former

land connection, since such land connections as he finds it necessary to

postulate would apparently involve the presence on these islands of con-

tinental faunz which are not now present, and whose absence cannot be

reasonably accounted for. For the reasons already presented I see no

difficulty in supposing that the crayfish of Cuba, Madagascar, New

Zealand or Fiji have reached those islands by accidental transport of

natural “rafts” through the agency of ocean currents, or by other acci-

dental means. The Australian and South American crayfish I should

regard as derived from the north, by way of the existing or slightly sub-

1A. E. ORTMANN: “Geographical Distribution of Fresh-water Decapods and its Bear-

ing upon Ancient Geography,” Proc. Amer, Phil. Soc., vol. xli, pp. 267-400. 1902.

302 ANNALS NEW YORK ACADEMY OF SCIENCES

merged land bridges,.at a time when the northern crayfish were much

more primitive than now, and when, for reasons which I do not venture

to suggest, the tropics were a more favorable environment than now.

The northern crayfish have since evolved into Potamobius and Cambarus,

the southern specialized into the more divergent Parastacus of South

America, Cheraps and Hugeus and Astacopsis of Australia and Tasmania,

Paranephrops of New Zealand and ? Fiji arid Astacoides of Madagascar,

Of these southern genera, Astacoides is the nearest to the northern

types. This is to be expected, if the southern genera are remnants of a

cosmopohtan distribution derived by dispersal from the north; for the

Malagasy genus would be a derivative from Ethiopian crayfish, which

would be Jess remote from the north, and would be correspondingly more

advanced than in South America or Australia. As far as the more

special distribution of the northern crayfish is concerned, Dr. Ortmann’s

paper affords data for the following interpretations.

Two genera are concerned, Cambarus of the eastern Sonoran region,

and Potamobius (Astacus of most authors) of the Old World and western

Sonoran region.

In his discussion of the genus Cambarus Ortmann states that the

more primitive forms of the first, second and fifth groups belong chiefly

to the south towards Mexico, and interprets this as meaning that the

genus came from Mexico. But, according to the principles here adopted,

this should mean that the center of dispersal is to the north and east;

and the discontinuity in range to the south and west is exactly what we

should expect, Dr. Ortmann’s attempt to find an explanation for it on

the opposite theory of migration being curiously complex and unconvine-

ing. The most primitive species occur in such widely divergent points

as Mexico and Cuba.

The more primitive genus Potamobius has a more discontinuous range,

in Europe, part of Eastern Asia and Western North America, the Asiatic

species being nearest to Cambarus (i. e., highest in development) but

parallel, not truly closely related. This, I take it, is correctly interpreted

by Ortmann as indicating an Asiatic center of dispersal for this genus.

But in place of supposing with Ortmann that Cambarus originated from

species of Potamobius pushing down southward into Mexico and thence

northward again (as Cambarus) into the United States, it seems to me

that the rational explanation would be to suppose that both genera are

the disconnected remnants of a formerly Arctic center of dispersal. This

would be first split in two by a progressively unfavorable environment,

one division passing down into America east of the Cordilleras, and

developing into Cambarus, the other part in Asia progressing more

MATTHEW, CLIMATE AND EVOLUTION 303

slowly into Potamobius and spreading east and west from that center,

as the American group spread southward.

DISTRIBUTION OF HELIX HORTENSIS

Dr. Scharff!?? regards the distribution of Helia hortensis as an im-

portant part of the evidence in favor of a late Cenozoic bridge connecting

Europe with eastern North America. The species is well known in

Europe and has always been regarded as indigenous there. It occurs

along the North Atlantic coast, and in Labrador, Greenland, Iceland and

the Shetland and Faroé Islands. It was formerly considered as intro-

duced on this side of the Atlantic by human agency; but it has been

found in old Indian shell-mounds and more recently in undoubtedly

Pleistocene deposits in Maine. It is unknown in Asia or western North

America. Hence, Dr. Scharff concludes that it must have migrated from

_ Europe to America across a land bridge via Iceland and Greenland in

Pliocene or Pleistocene times.

The early opinion that Helix hortensis is an introduced species in this

country was founded, so far as I recall, mainly upon the peculiar local

range and habitat of the species, very different from the truly indigenous

New England land-snails, and my early experiences in land-snail collect-

ing in southern New Brunswick were quite in accord with this evidence.

It is quite possible that Helix hortensis, like the genus Hquus, is both

introduced and indigenous.

Granting that it is at least partially indigenous, what evidence is there

that the present distribution is not the remnant of a Tertiary circumpolar

distribution? The fact that it is not recorded in the Tertiary of Asia?

But what proportion of the presumably abundant Miocene or Pliocene

land-snails of Asia is known to us? It can only be a minute fraction

at the best—less than one per cent. So the chances are a hundred to one

that if Helix hortensis or an ancestral form of the species existed in the

Tertiary of North Asia, we should have no record of its existence at

present. We do, however, have a good deal of indirect evidence that an

environment favorable to the present habits of the species existed during

the later Tertiary in the region intervening between its present discon-

tinuous distribution areas, and that the environment became unfavorable

in that intervening region at the close of the Tertiary. I can see no

need for assuming a transatlantic land bridge to account for the distribu-

tion of this species. And the explanation here suggested is in harmony

with the known course of distribution of those members of the northern

22 R, F. ScHarrr: Proc. Roy. Irish Acad., vol. xxviii, p. 19. 1909.

304 ANNALS NEW YORK ACADEMY OF SCIENCES

land faunz whose past history is preserved to us in the geologic record.

It involves only those minor changes of continental level (a few hundred

feet) of whose occurrence during the Pleistocene we have ample evidence.

On the other hand, if we assume such a Transatlantic land bridge

during the late Tertiary we must suppose an elevation of upwards of

five thousand feet, a huge disturbance of the isostatic balance of whose

possibility we have no real evidence; for the submerged channels so often

cited in support of these immense uplifts have been shown by Chamberlin

to be much more probably due to “continental creep,” to the slipping”

down, so to speak, of marginal sediments to a lower level.'** In any

ease, there could be no evidence as to the period at which these old

channels were last above water. They may have been submerged since

the Permian, for aught we know to the contrary. Furthermore, we have

to explain the non-migration of a multitude of forms which got just so

far as conservative land elevations could carry them, but no farther.

DISTRIBUTION OF PERCIDA

Another instance upon which Dr. Scharff lays great stress is the dis-

tribution of the perches. Here, the false impression produced by the

use of a Mercator’s projection map in plotting the distribution of north-

ern forms, seems to me to be very obvious. ‘This map does not give the

northern regions in their true proportions or relations. Transferring

the distribution of this family as plotted by Tate Regan, to a north polar

projection map we get the real relations and proportions with approxi-

mate correctness. It then becomes obvious that the perches are centered

around the drainage basin of the Arctic ocean. In North America they

have extended down the Atlantic coast drainage area and into that of the

Gulf of Mexico as far as the Rio Grande. In Asia they have been ad-

mitted by the old Hyrcanean Sea into the present Caspian and Aral

basins; and a glance at the late Tertiary geography of Europe will show

how they have reached the drainage basin of the northern Mediterranean.

They are not now found in the Arctic drainage area of western North

America, Greenland or Iceland, where the environment, now or in the

Pleistocene, is amply sufficient to account for their extinction. What

need of a transatlantic land bridge to account for this distribution.

23There is another possible explanation. The progressive building out seaward of

barrier reefs around a number of separate centers until they joined into a platform

would naturally leave deep intervening channels, especially off the mouths of great rivers

where the influx of mud and fresh water hindered the growth of the coral organisms.

The submarine contours around the West Indian islands especially suggest this explana-

tion, which I offer tentatively for the consideration of my better-versed confréres,

MATTHEW, CLIMATE AND EVOLUTION 305

A fourth instance cited by Dr. Scharff is the distribution of the river-

mussel Margaritana, and as he well observes, numerous other instances

would probably show similar discontinuous distribution. But, so far as

I have been able to find such instances, the same reasoning and the same

explanation apply to them all.

Criticism oF Some Opposing HypoTHEsEs

It is not practicable to take account here of the flood of paleogeo-

graphic discussions of recent years which have advocated all sorts of

consistent or inconsistent changes in continental outlines. They agree

for the most part in failing to take into account certain considerations

which to my mind are essential elements in any problem of distribution.

Among the geological considerations are the following:

1) Evidence that the present distribution of the deep ocean basins is

in the main due to isostatic balance. This affords a strong presumption

in favor of its permanence.

2) Absence of abysmal deposits in the geological formations of any

continental region. Chalk deposits are not an exception, as it has been

shown that they were deposited in shallow epicontinental seas rather than

in deep oceanic basins.

3) Abrupt ending of an elevated line of disturbance and its continua-

tion as a submerged line of disturbance does not necessarily indicate that

the submerged portion was formerly elevated, although it does reduce

the improbability of its former elevation by indicating a line of dis-

turbance and hence of possible elevation.

4) The presence of marine formations of Cretaceous or Tertiary age

over large portions of the interior of the great continents does not indi-

cate that these continents first came into existence as such during the

Cretaceous or Tertiary. In the better known portions of the earth’s

surface we know well enough that these marine formations were due to

‘periodic temporary submergence, interrupted by periods of more or less

complete emergence. It is but reasonable to apply the same explanation

to the less known regions. I see no more reason to suppose, as do Von

Thering, Scharff and others, that South America first came into existence

as a united continent in the Tertiary, than to conclude on similar evi-

dence that North America was but a group of isolated land masses until

the end of the Cretaceous. In this country, we have positive proof of

its antiquity; but the evidence for recent origin of the South American

would apply just as well to the North American continent. A similar

presumption of antiquity applies to Australia, Asia and Africa.

306 ANNALS NEW YORK ACADEMY OF SCIENCES

Among zodlogical considerations we may mention the following:

1) The discontinuous distribution of modern species is again and

again taken as proof that the regions now inhabited must have been con-

nected across deep oceanic basins, without considering the possibility that

it is a remnant of a wider past distribution, or that it is due to parallel

evolution from a more primitive type of intermediate distribution, now

extinct. Yet so many instances are known where the geological record

has furnished proof that one or other of these explanations applies to

cases of discontinuous distribution, that it would seem that these ought

to be the first solutions of the problem to be considered, and that in view

of the known imperfection of the geologic record, mere negative evidence

is not sufficient to cause them to be set aside.

2) No account is taken of faunal interchanges often much more ex-

tensive, which would presumably have taken place if the land bridges

assumed had existed, but which have not taken place. It may here be

urged that this too is negative evidence. But the negative evidence de-

rived from an appeal to the geological record is weak, not per se, but

because of the demonstrated imperfection of this record. On the other

hand, there are many instances where a land bridge is well proven, and

in these cases it is not a few scattered exceptions but an entire fauna

that has migrated, subject only to the restrictions imposed by climatic or

topographic barriers of other kinds.

I may venture upon a discussion of a few instances in order to show

the type of objections which appear to me to apply to much of the evi-

dence cited in favor of most of these transoceanic land bridges.

On VAIN SPECULATIONS

According to some distinguished paleontologists,1** progress is to be

made only by ignoring the possibility that races have originated in or

migrated from regions of whose former life we have substantially no

record, and assuming that they must have evolved in one or another re-

gion where the record is more or less known, and that the actual record

must be the sole basis for any conclusions. They refuse to consider the

arguments for origin elsewhere, on the ground that such hypotheses are

“vain speculations” and “serve merely to conceal our ignorance.”

To this I may answer that a fair and full consideration of the data at

hand shows that such hypotheses, of one kind or another, are absolutely

necessary, unless we are to abandon all belief in the actuality of evolution

and are to treat it as merely a convenient arrangement of successive spe-

124 Depéret, Thévenin and others.

MATTHEW, CLIMATE AND EVOLUTION 307

cies and faunas independently created. Such a view was held by Agassiz

and most of his predecessors, but it is unnecessary to consider it in the

present state of scientific belief.

If, on the other hand, we accept the belief that the successive species

of each phylum are genetically related, how are we to explain the fact

that these phyla are usually approximate and not direct, and that where

the evidence is most complete, the fact that they are not in a direct lne

of structural evolution stands out most clearly. Take for example the

ancestry of the horse, the most striking, easily recognizable, widely known

and thoroughly studied illustration of mammalian evolution. It was

possible, when the “documents” were few and imperfect, to trace a sup-

posedly direct line of ancestry through European predecessors. Later,

when the fossil fields of the western United States were first explored, a

much more direct line of ancestry was found in this country, and the

European series was recognized as not being the direct line. But the

further progress of exploration in America, and the discovery of complete

skeletons of the supposed ancestral stages known at first only from frag-

mentary specimens, has demonstrated that this line too is an indirect and

approximate series so far as the succession of the known species is con-

cerned. This has been recognized in recent years by American students,

and variously phrased or interpreted. The most probable explanation of

the facts is to suppose that the known phylum is approximate, not direct ;

that the direct line of descent leads through unknown or imperfectly

known species, and that those known to us are offshoots of varying close-

ness. The direct line is, then, admittedly through hypothetical species,

and the only question is whether the habitat of these species was in the

regions where we have searched vainly for their remains, or in the much

greater intervening region where we have not searched. Horses are found

throughout the Tertiary in central and western Europe on the one hand,

on the Western Plains of America on the other. There is every reason to

believe that they inhabited all or parts of the intervening region and we

have no right at all, in weighing the evidence, to refuse to take this re-

gion into consideration, on the plea that it has furnished no “documents”

as yet. To place such limitations on our theories would hardly tend to

solving our problems, however much it might seem to simplify them. It

is merely to prefer a conclusion that we know to be false to a conclusion

that we cannot prove by direct evidence to be true.

What I have stated in regard to the fossil ancestry of the horse applies

to most mammalian phyla, in greater or less degree according to the per-

fection and number of our “documents.” Where these are few and frag-

mentary, it is still possible to build up phyla which cannot be proven to

308 ANNALS NEW YORK ACADEMY OF SCIENCES

be inexact. But, as knowledge increases and becomes more exact, these

phyla are more and more broken and complex, and direct genetic series

become more limited in extent. This is to be expected, for the regions

which up to date have been at all thoroughly explored are but a small

fraction of the area which the group concerned must have inhabited.

And on @ priori grounds, the chances are greatly against the particular

species which was to become dominant inhabiting the particular regions

which we have explored.

Professor H. F. Osborn has very well expressed the conditions of evo-

lutionary progress by stating that each group is highly polyphyletic, con-

sisting of numerous subphyla evolving along more or less parallel lines.

But we are here concerned less with the disentaglement of the subphyla

of a group than with its dominant center of dispersal as a whole. And

from this point of view it seems to me misleading and erroneous to as-

sume that it must have migrated only from one to others of the regions

where its remains have actually been found, instead of attempting to

locate from the indirect evidence available the true center of dispersal.

In contrast with the views here criticized, I may venture to quote from

an address in which Dr. Stehlin?®® has recently summarized the phylo-

genetic results of his monumental studies upon the Eocene fauna of Eger-

kingen, a work of extraordinary thoroughness and ability which, as a

recent reviewer observed, has involved a revision of the entire Kocene

mammal fauna of Europe: “Where then dwelt these yet unknown herds

of mammals evolved during the Eocene, whose existence is recorded

through their influence upon Europe and North America the more clearly

as we analyze more closely the data obtained in these continents? We

can scarcely be wrong if we look to the huge continental mass of Asia,

still almost unexplored by the paleontologist. The future, and, it may be

hoped, the near future will show how far our present anticipations are

correct.”

SUMMARY OF EVIDENCE

The geologic evidence for the general permanency of the abyssal oceans

is overwhelmingly strong. The continental and oceanic areas are now

maintained at their different levels chiefly through isostatic balance, and

it is difficult to believe that they could formerly have been reversed to any

extensive degree. The floor of the ocean differs notably in its relief from

the surfaces of the continents, and only in a few limited areas is the relief

suggestive of former elevation above sea-level. The continental shelf is

2H. G. STEHLIN: Verh. Schw. Naturf. Gesell., 93 Jahresversammlung, Sept. 1910.

P. 29 of separata.

MATTHEW, CLIMATE AND EVOLUTION 309

so marked, obvious and universal a feature of the earth’s surface that it

affords the strongest kind of evidence of the antiquity of the ocean basins

and the limits beyond which the continents have not extended. The

supposed evidence for greater elevation in the erosion channels across its

margin have been shown to be better interpreted as due to “continental

creep.” The marine formations now found in continental areas have all

been deposited in shallow seas. No abyssal deposits have ever been cer-

tainly recognized among the geologic formations of the continental plat-

form.

Leaving out of consideration speculative hypotheses as to a formerly

smaller amount of water on the surface of the globe, shallower ocean

basins in Paleozoic times and different land and water distribution in the

older geological periods, it is sufficient for the purposes of this discussion

to emphasize the great weight of geological and physiographic evidence

for the permanency of the continental masses as outlined by the conti-

nental shelf, during the later geological periods, and especially during the

Tertiary.

The present distribution of continents and oceans on the surface of the

globe (as outlined by the continental shelf) consists of a great irregular

northern mass including Europe, Asia and North America, with three

great partly isolated projections into equatorial and southern latitudes,

South America, Africa and Australasia, and a smaller Antarctic land

mass wholly isolated. The three peripheral continents are isolated from

each other and from the Antarctic land by broad and deep oceans, but

with the doubtful exception of Australasia, are united to the central mass

by shallow water or restricted land connections.

A rise of 100 fathoms would unite all the continents and continental

islands, except perhaps Australia, into a single mass, but would leave

Antarctica, New Zealand, Madagascar, Cuba and many smaller islands

separate. A further elevation of five times this amount would not alter

materially the boundaries of land and sea. A submergence of 100 fath-

oms would isolate the three southern continents, and cause shallow seas

to spread widely over the interior of all the continental masses, reducing

some of them to isolated fragments or archipelagoes.

Such cyclic alternations of emergence and overflow are recognized by

many geologists as the dominant feature of the earth’s history, corre-

sponding to the succession of periods into which geologic time is divided.

The greater disturbances resulting in folding, faulting and mountain

making, while involving much greater changes of level, affect more lim-

ited areas, adjacent to lines of unstable equilibrium, especially along the

borders of the continental platforms.

310 ANNALS NEW YORK ACADEMY OF SOIENCES

Associated with these great cycles of elevation and submergence are

climatic cycles from extremes of cold or arid zonar climates culminating

in glacial epochs, to the extremes of warm humid uniform climates which

accompany or follow the extremes of submergence.

The effect upon terrestrial life of progressive elevation of the land

areas, accompanied by a progressively cold climate at the poles and arid

climate in the interior of continents, would be to adapt the terrestrial

life to cold, arid and highly variable climatic conditions. The environ-

ment favorable to this adaptation will appear first near the poles, and the

northern and southern faune will be more progressive and will tend to

disperse towards the equatorial regions. The wider area of emerged con-

tinents will tend to expansive evolution of the land faunz, and their

union into a single land mass will facilitate cosmopolitan distribution.

Owing to the conformation of the continents the dispersal will be chiefly

from the Holarctie region, the Antarctic and southern lands being unfa-

vorably situated for the evolution and dispersal of dominant races and

contributing but little to the cosmopolitan faune of the emergent phase.

These conditions are also favorable to the development of higher, more

active and more adaptable types of terrestrial life, which tend to supplant

even in moist tropical regions the less adaptable remnants of the tropical

faune which find there their last refuge.

During the opposite phase of the cycle, the faunz become progressively

readapted to the moist tropical climatic environment. But owing to the

higher evolutionary stage acquired during the arid phase, the higher and

dominant types of the new fauna are evolved chiefly by readaptation of

the dominant types of the arid phase and only subordinately by expansive

evolution of the tropical fauna surviving through that phase.

The paleontologic record appears to be in exact harmony with these

principles, provided due allowance be made for its imperfections. The

geographic distribution of animals and plants affords far more complete

data, but their true significance has in my opinion been misinterpreted

by many zodgeographers. When interpreted in harmony with the prin-

ciples of dispersal shown to be true among mammals, they yield fully

concordant results. The geologic record is to-day far more incomplete

than is generally admitted, and will always be incomplete. Negative evi-

dence, while sometimes of high value, is more often worthless and should

never be admitted without a careful canvass of the situation in each

instance.

The population of oceanic islands is notably incomplete and cannot be

interpreted as due to continental connection. The difficulties in the way

of over-sea transportation are best explained by the hypothesis of natural

MATTHEW, CLIMATE AND EVOLUTION 311

rafts; the degree of probability that attaches to this hypothesis is esti-

mated.

The dispersal of mammals is then considered at some length, order by

order, and it is shown to accord fully and in detail with the principles

here set forth, and to be impossible of explanation except upon the

theory of permanence of the ocean basins during the Cenozoic era. While

the prominence of the Holarctic region as a center of dispersal is ascribed

to its central position and greater area, some evidence is given to show

that climate is also a factor in the greater progressiveness of the northern,

since it is also noticeable in the southern as compared with tropical faune.

The distribution of the Reptilia appears to be in conformity with the

principles here outlined, and extends their application to the Mesozoic

era. The distribution of birds and fishes and of invertebrates and plants

is probably in accord with the same general principles, modified by differ-

ences in methods of dispersal. The opposing conclusions that have been

drawn from the distribution of these groups are believed to be due to an

incorrect interpretation of the evidence. A few instances, which have

been prominently used to support opposing conclusions, are analyzed and

shown to conform to the conclusions above set forth, if interpreted upon

similar lines as the data for mammalian distribution.

APPENDIX

Since this paper was written two very readable and instructive books

on geographic distribution have appeared, “The Wanderings of Animals”

by Professor Gadow,?*° and “Distribution and Origin of Life in America”

by Professor Scharff.1°*7 Both writers, and especially Doctor Scharff, be-

long to what may be called the bridge-building school of paleogeography,

and the general criticisms expressed in the earlier part of this article

apply largely to their interpretations. It is with no intent to depreciate

their value that I observe that there are numerous errors of fact in those

portions of the evidence with which I am best acquainted, for in a subject

of so wide a scope most of the evidence is necessarily compiled and not

very well understood, and errors more or less essential will slip in. It is

for that reason that I have avoided detailed discussion of the parts of

the evidence on the present subject with which I am not well acquainted ;

and, in spite of a good deal of checking and revision, I have no doubt

that the foregoing discussion contains various inaccuracies.

26 HANS Gapow: “The Wanderings of Animals.’’ Cambridge Manuals of Science and

Literature, No. 64. 1913.

VR, F. Scuarrr: Distribution and Origin of Life in America. Macmillan Co., pub-

lishers, New York. 1912.

312 ANNALS NEW YORK ACADEMY OF SCIENCES

A more serious criticism is the illegitimate and often partisan use

made of negative evidence. This is doubtless due to the same cause, a

mere book knowledge of the fossil record, and failure to examine and

weigh its evidence. But it is very obviously affected by a readiness to

rely on negative evidence that favors their theories and to ignore a vastly

greater amount of negative evidence that does not.

\” forsthe theory of Holaretic dis-

Dr. Gadow considers it “awkware¢

persal of the marsupials in the Cretaceous that no survivors have been

recorded in the Tertiary of Asia. He prefers to believe that the Aus-

tralian marsupials arrived via Antarctica from South America. If it is

“awkward” for the one theory, that although survivors are found in the

early Tertiary of both Europe and North America, none have been found

in Asia, then it must be equally “awkward” for the theory that Dr.

Gadow supports that none have been found in Antarctica. For we know

even less about the early Tertiary of Asia than we do about the Antarctic

Tertiary. If the absence of zalambdodont insectivores in the Eocene of

Europe is to be assigned any weight, then equal weight should be assigned

to their absence from the Oligocene and Eocene of South America and

from the Pleistocene of Cuba, of Madagascar and South Africa. We

know as much about the one fauna as we do about the others. The

negative evidence has no weight in any of these instances; per contra,

the fact that zalambdodonts are known to have lived in the early Tertiary

of North America (Paleocene to Oligocene) affords a presumption of

their presence in the nearly allied early Tertiary faunas of Europe, just

as their presence in the recent faunas of Madagascar and South Africa

and in the Miocene of South America affords a presumption of their

presence in the nearly allied faunas which immediately preceded them.

Equally, the presence of marsupials in the early Tertiary of Europe on

one side of Holarctica and of North America on the other side raises a

strong presumption of their presence in the intervening region of Asia

from which no fossils are known. ‘They are not found in the later Ter-

tiary of Europe and America, so that we should not expect to find them

in the later Tertiary of Asia. On the contrary, the small fragment of

evidence that we have as to the Tertiary fauna of Antarctica affords a

slight presumption against the presence of mammals on that continent.

Doctor Gadow’s statement that the Chiroptera did not reach America

until the Pleistocene is another curious instance of the misuse of the

fossil record, which no one familiar with the character of our Tertiary

formations and the necessary limits of the fossil faunas would be likely

to make; nor would anyone acquainted with the variety and specializa-

tion of the New World genera be inclined to believe that it was all the

MATTHEW, CLIMATE AND EVOLUTION 313

result of post-Pliocene immigration and differentiation. Most of the

ereodonts, he informs us, “died out with the Eocene or rather they were

modernized into the typical Carnivora in various parts of the world.

Some, however, kept on to almost recent times as highly specialized

creodonts, e. g. the sabre-toothed tigers: Nimravus in North American

Oligocene; Machewrodus from Miocene to Pleistocene in Europe and

Asia, whence in the Pleistocene it appeared as Smilodon in America.

: 8 Tt is perhaps unnecessary to point out that the macherodonts

were not creodonts but typical Carnivora of the family Felidae, and that

their evolutionary series is fully as complete and progressive in the

Nearctie as in the Palearctic record. I may also note that “small swine”

(meaning I suppose the primitive bunodont artiodactyles from which

both pigs and peccaries are derived) appeared in North America quite

as early as in Europe; that the genera Procamelus and Pliauchenia do

not mark the splitting of the Camelide into camels proper and llamas;

that Dorcatherium is not identical with “Hyomoschus”’ (Hyemoschus)

and is an older name; that Arsinoitheriwm is not a pair-horned dicera-

there but is a representative of a distinct order of mammals; that the

precise relations of the American Eocene tapirs have yet to be deter-

mined; that Protapirus does not first appear in the Lower Oligocene of

Europe but in the Mid-Oligocene of Europe and North America; that

there is no reason to believe that the European Paratapirus is more di-

rectly in line of descent of the later tapirs than is the so-called Tapiravus

of the American Miocene, and that the very fragmentary and inadequately

studied record of the evolution of the Tapiride is quite inadequate for

the positive and exact statements which Gadow makes as to their “wan-

derings.”

The statements as to the evolution of the horse show a surprising

amount of inaccuracy, considering that this is so widely known a story.

Apparently, it is in part the result of an attempt to criticize and modify

the conclusions of American writers on the basis of a hasty survey of

the incomplete materials available in European museums. The Eocene

ancestors are disregarded, because they “are still so very generalized that

they lead to horses, rhinos and tapirs as well as to other distinct groups.”

While this is not far from the fact as regards the Lower Eocene Hohippus,

it certainly is not true of Orohippus and Epihippus of the Middle and

Upper Eocene. The relations of Miohippus to Mesohippus are hardly

to be dismissed with a “perhaps.” Desmatippus is not an ancestor of

Parahippus but is identical; Hypohippus is not intermediate between

Para- and Merychippus but is an aberrant type descended from Miohippus

128 Op. cit.

314. ANNALS NEW YORK ACADEMY OF SCIENCES

through Anchitherium; the American Miocene series does not come to

an end with Merychippus, but this genus gives rise through numerous

intermediate species to Protohippus, Phiohippus and Hipparion. Hip-

pidion is not a descendant of Hipparion but of Pliohippus. There is, it

is true, a considerable gap between Hipparion gracile and Hquus, this

species being too specialized in tooth pattern and its lateral digits ex-

ceptionally heavy; but most of the Ameritap hipparions are simpler and

less aberrant in tooth pattern and the shafts of their lateral digits reduced

often to mere threads. The proximal splints in these forms are very

nearly as much reduced as they are in Hquus; the gap which Doctor

Gadow declares has been “slurred over” lies simply in the fact that no

specimens have yet been found in which the shafts of the lateral digits

are discontinuous but the distal rudiments preserved. Anyone familiar

with the difficulty of securing proof of this condition in a fossil species,

and with the imperfection of our record of the Pliocene Equid, will

hardly consider this as a serious gap. Certainly, it is trifling in com-

parison with the gaps in any of the other mammalian phyla which Doctor

Gadow accepts without difficulty. As for the derivation of Hquus from

primitive species of Hipparion rather than of Protohippus, my opinion

to that effect rests upon intensive studies of Miocene Equide undertaken

for Professor Osborn’s monograph of the Evolution of the Horse (in

preparation) and I do not think it fitting to publish the evidence in its

support at present.

The sirenians, Dr. Gadow tells us, afford strong support of the theory

of a transatlantic bridge, the earliest being known from the Kocene of

Jamaica and Egypt, ete. They would, undoubtedly, if there were suf-

ficient reason to believe that they were absent from the more northerly

parts of the North-Atlantic-Arctic shores during the early Tertiary. But

there is none whatsoever; the North Atlantic coasts either extended dur-

ing the Tertiary beyond their present limits to or towards the continental

shelf, or else their marine and littoral deposits have been destroyed by

glaciation; at all events none remain above water worth mentioning

from New Jersey on one side around to the British Isles on the other.

That no littoral vertebrates should be known where there are no littoral

deposits is not surprising; yet it is upon this worthless negative evidence

that the “strong support” rests.

I have limited myself in the foregoing criticism to noting a few points

in regard to fossil mammals. Dr. Scharff’s book is far too extensive for

any detailed criticism here, even within these limits. I can note only

that, while highly instructive as well as entertaining, it is far from being

either accurate or fair in its treatment of the geological aspects of the

MATTHEW, CLIMATE AND EVOLUTION 315

subject or the fossil record. The view-that during the Glacial Epoch

the glaciers were confined in this country to the higher mountain ranges’”®

is one that even a biologist is hardly excusable for upholding. Nor does

it seem that anyone discussing the Tertiary geography of North America

should be so little informed as to suppose*®® that the eastern and western

portions of the continent were separated during the EHocene by an ocean

barrier. In his argument against the permanency of the ocean basins,

Scharff is, on the other hand, able to quote high authority. But the

weakness of the argument is nevertheless apparent. That there have

been great changes of level along certain lines of disturbance has never

been questioned. But the conclusion that the continental platforms have

never been submerged to abyssal depths, based upon the entire lack of

abyssal deposits in their geological succession, is not disproved but rather

confirmed by the recognition of abyssal deposits on an oceanic island

lying along a line of high disturbance. For that merely proves that

abyssal deposits are recognizable as such when they do occur, absence

from the continental platforms remains untouched. Nor does the oc-

currence of ancient sedimentary and metamorphic rocks on some, espe-

cially of the larger, oceanic islands afford any evidence that they are

remnants of former continents. The same processes of sedimentation,

regional metamorphism and orogenic upheaval must of necessity occur

in any oceanic island of considerable size and antiquity, and produce

similar results both stratigraphic and petrographic. Moreover, if such

islands lie in a line of disturbance which is continued under the ocean

to an adjacent continent the same earth-movements may well affect both

areas without raising the intervening region above the abyssal depths in

which it now hes.

Dr. Scharff adopts Ameghino’s correlations of Argentine formations,

and Von Ihering’s assertion that the continent of South America did

not exist as a single land mass until late in the Tertiary. I may note

by the way that Ortmann'*! not long ago, in reviewing Pfeffer’s**? essay

on the zodgeographical relations of South America, rebuked him severely

for not being aware of this “undoubted fact,” which he declared was not

a theory at all. The real facts are that marine and fresh-water forma-

tions of Jurassic, Cretaceous and early Tertiary age occur extensively in

the interior of South America, indicating that the broad low-lying in-

terior of that continent was periodically flooded by shallow seas. The

conditions parallel those of the North American continent very closely,

122 Op. cit., pp. 46 ff.

190 Tbid., p. 357.

131 A, KE. ORTMANN: Amer. Nat., vol. xxxix, pp. 413-416. 1905.

182 G, PFEFFER: Zoél. Jahrb., Suppl. 8, pp. 407-442. 1905.

316 ANNALS NEW YORK ACADEMY OF SCIENCES

so far as they are known. ‘The North American continent we know

existed as such throughout geological time, although extensively flooded

at times by shallow seas, especially during the Middle Cretaceous. The

same is presumably true of South America.

Like Doctor Gadow, Doctor Scharff makes a wholly unjustifiable use

of negative evidence where it may serve to support his views. He is a

much more reckless bridge-builder, and appears to be quite unconscious

of any difference in probability between such a bridge as the Alaska-

Siberia connection and the various trans-Atlantic and trans-Pacific

bridges which he invokes. Yet the Alaskan bridge is in existence to-day,

only a few yards of its planking removed, if one may so speak, the sub-

structure intact, and the marks of the missing planks still showing on

the undamaged portion, while the huge bridges which he “prefers” to

believe in are, except for the Icelandic ridge, scarcely indicated by so

much as a sandbank on the flat abyssal floor of the vast intervening

oceans. That he can claim support of a kind from so high an authority

as Suess may be true, but scientific problems should be settled by ex-

amination of the evidence, not by citations of opinion from selected

authorities. “et

Doctor Scharff does not at all believe in accidental transportation by

floating vegetation or other natural means. Why, he demands, do not

the advocates of such views cite instances of such transportation in mod-

ern times, and why is it only the more ancient animals that are so trans-

ported? The argument is curiously parallel to the favorite anti-evolu-

tionist demand. Why, if man has evolved from a monkey, do not the

scientists take a monkey and turn him into aman? Of course, the proof

demanded is an impossibility. If any instances of such transportation

were noted during the last few centuries, they would be ascribed to

human agency; but the probabilities within that time are slight except

in islands near the coast, such as Krakataua; for more distant islands

they are made probable only by the vast length of geological periods, and

it is a matter of course that the more ancient the type, the longer time

and consequently better chance there has been for its transportation by

accidental agencies.

Like all authors who advocate union of the Galapagos islands with the

mainland, Dr. Scharff does not distinguish between a union of the islands

with each other, which is geologically probable and is an almost unavoid-

able conclusion from a study of the fauna, and their union with the

mainland, which is highly improbable on geological and physiographical

grounds, and is not merely unnecessary to explain the fauna but im-

possible to reconcile with its peculiarities by any reasonable theories

which take into account all of the consequences of such union.

MATTHEW, CLIMATE AND EVOLUTION 319

While Doctor Scharff’s interpretation of the data is based upon funda-

mentally different principles above noted, and his statements as to fossil

distribution are often inaccurate or incomplete, yet the numerous dis-

tributional data which he presents of modern invertebrates are of great

interest, and, if interpreted along the lines which I have used, they fall

completely into line with the vertebrate evidence. We cannot usually

indeed check the conclusions drawn from modern distributional relation-

ships by the fossil record. Many groups are altogether unknown, and

the record in others is very scanty, but the same general relations clearly

apply. The survival in Western Europe on one side, in southeastern

North America on the other side, of a somewhat primitive cycle of Hol-

arctic distribution ; the survival in the Mediterranean region on one side,

in Central America and the Antilles on the other, of a more primitive

cycle; of a still more primitive cycle in Africa and South America; and

the progressively greater amount of divergent or parallel specialization

in the survivors of the earlier cycles; the antique and fragmentary char-

acter of the faunx of the oceanic islands, progressively more so in pro-

portion to their smallness and isolation—all these conform to the verte-

brate distribution. And with invertebrates as with vertebrates, every

year adds to the number of the types which, while now limited to the

peripheral continents and oceanic islands and highly discontinuous in

their range, are shown to have inhabited formerly the central Holarctic

region. It appears that many, one might perhaps say most, invertebrates

are more readily transported across ocean barriers than vertebrates, espe-

cially mammals, even making due allowance for their greater antiquity.

This also we should expect.

I do not think it necessary to catalogue the errors or inaccuracies in

presenting the evidence afforded by fossil vertebrates. Such errors are

unavoidable in a subject of so broad a scope, and excusable enough, if

they do not lean too much to one side. I shall cite but one instance,

and this in justice to my distinguished confrére Professor Depéret.

Doctor Scharff concludes his summary of the North American records

of the Evolution of the Horse with the following remarks :1%* “And yet

not a single transition from one genus to the other seems to be known.

No wonder that one of our foremost paleontologists exclaims, “The sup-

posed pedigree of the horse is a deceitful delusion, which simply gives

us the general process by which the tridactyl foot of an ungulate can be

transformed in various groups into a monodactyl foot in view of an

adaptation for speed, but this in no way enlightens us on the paleontolog-

ical origin of the horse.’” Such a statement, coming from so excellent

183 Op. cit., p. 147.

318 ANNALS NEW YORK ACADEMY OF SCIENCES

an authority, seems startling until one verifies the quotation and finds

that it refers, not to the American records, but to the ancestry of the

horse as presented in Gaudry’s'** Enchainements, to the European series

Paleotherium, Anchitherium, Hipparion gracile and Equus. Depéret

takes care to premise that he is speaking only of this European series,

and while I think the criticism goes too far—it should at least be modi-

fied by changing “ungulate” to “perissodactyl” in view of what we know

about the Litopterna—yet the criticism is largely justified in its proper

context. As applied to the American series it is altogether unwarranted.

1% A, GAUDRY: Enchainements du Monde Animal, vol. iii, Mammiferes tertiaires. 1878.

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PRESS OF JUDD & DETWEILER, INC., WASHINGTON, D. C.

ANNALS OF THE NEW YORK ACADEMY OF SCIENCES

Vol. XXIV, pp. 319-346, pll. XXII-XLI

Editor, EpmMuND OTIs Hovey

DEVELOPMENT OF THE NEURAXIS IN THE

DOMESTIE:-CAT. [QO THE STAGE

OF TWENTY-ONE SOMITES

H. von W. ScHULTE AND FREDERICK TILNEY

NEW YORK

PUBLISHED BY THE ACADEMY

31 Marcu, 1915 -

acai

ape

THE NEW YORK ACADEMY OF SCIENCES

(Lyozum or Natural Hisrory, 1817-1876)

OFFIcErs, 1914

President—GrorGE FREDERICK Kunz, 601 West 110th Street

Vice-Presidents—CuarLrEs P. Berkey, RayMonp C. Ospurn,

CHARLES BASKERVILLE, CLARK WISSLER

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Recording Secretary—EpmuND Otis Hovey, American Museum

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Natural History, 77th Street and Central Park, West.

fAnnats N. Y. Acap. Scr., Vol. XXIV, pp. 319-346, Pll. XXIJI-XLI.

31 March, 1915]

DEVELOPMENT OF THE NEURAXIS IN THE DOMESTIC CAT

TO THE STAGE OF TWENTY-ONE SOMITES*

By H. von W. ScHULTE AND FREDERICK TILNEY

CONTENTS

Page

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RUHOM Pence pHalomerrre,cvereiwrevozs tele ve coher aio erates ic eve Sie eer ae ome escetecueiearelorererers 344

INTRODUCTION

The present paper is a study of the morphogenesis of the neuraxis in

its early stages, with especial reference to an attempted interpretation

of the forebrain in terms of the longitudinal zones of the neural tube,

viz., the basal and alar laminew, and the ganglionic crest. The theoretical

problem can be stated briefly. Since the ganglionic elements are in-

cluded in the wall of the neural tube at the time of its separation from

the ectoderm—Neumayer has shown this for reptiles, and it is also true

1 Presented in abstract by the senior author at the meeting of 11 May, 1914, under

the title “Early Stages in the Development of the Brain in the Domestic Cat.”

Manuscript received by the Editor, 17 September, 1914. :

(319)

320 ANNALS NEW YORK ACADEMY OF SCIENCES

of the cat—it is possible that in regions in which a ganglionic crest is

not formed, homodynamous elements remain incorporated and form

permanent constituents of the brain-wall. It ought not to be inferred,

from absence of a discrete ganglionic crest in any region, that its equiva-

lent is lacking, for it may simply have failed to separate from the

neuraxis. On the other hand, with regard to the interpretation of the

forebrain in terms of transverse segmentation, neuromeres, it would seem

that a complete dorso-ventral segment of the neural tube should contain

ganglionic, alar and basal elements, and that failing any of these it is

something less and other than what the term neuromere properly implies.

Now we have no evidence of the existence of the basal lamina in advance

of the nucleus of origin of the oculo-motorius, nor can we see the ad-

vantage of assuming its presence in front of the point at which evidence

of its existence ceases. Further, the transverse segmentation of the neu-

raxis is either the result of intrinsic factors, or what seems more probable,

is at least in part secondary to the segmentation of the mesoderm. This

is myomeric in the trunk, branchiomeric in the head. That a secondary

segmentation of the neuraxis thus effected should result in a continuous

series of meristic equivalents seems on the face of it somewhat improb-

able. These, in brief, are the questions we have had chiefly in mind in

attempting an ontogenetic analysis of the forebrain of the cat. At the

same time it seemed desirable to record the general data concerning the

neuraxis in a close and fairly numerous series of young embryos, for as

vet the knowledge of these stages in mammals is far from extensive.

The list of embryos is as follows:

Prior to the appearance of somites......... «secre NOS. 339, 400, 456, 550, 555

One pair of mesodermic somites................ --. Nos. 554, 594 °

Two pairs of mesodermic somites................. No. 539

Three pairs of mesodermic somites................ No. 593

Four pairs of mesodermic somites................. No. 409

Seven pairs of mesodermic somites................ Nos. 587. 588

Hight pairs of mesodermic somites................ Nos. 530, 586

Nine pairs of mesodermic somites................- No. 531

Ten pairs of mesodermic somites........... Seee ose INOS 476) 582

Twelve pairs of mesodermic somites............... Nos. 534. 547

Thirteen pairs of mesodermic somites.............. No. S6

Fourteen pairs of mesodermic somites............. Nos. 188, 548

Sixteen pairs of mesodermic somites.............. No. 551

Seventeen pairs of mesodermic somites........ «eee NO. 968

Nineteen pairs of mesodermic somites............. No. 502

Twenty-one pairs of mesodermic somites........... No. 558

The embryos were cut into transverse sections and reconstructed by

the Born method at a magnification of two hundred diameters. Casts

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 321

of the lumina, as well as models of the neural tube, were made in each

case and were found useful in controlling and interpreting the surface

relief. The period of development of the neuraxis covered by these

embryos extends from the appearance of the medullary plate to the

definition of the pallial anlage. It will be convenient, first, to record the

conditions observed in the several embryos and then proceed to a con-

sideration of the morphological questions outlined above.

DESCRIPTION OF EMBRYOS

Embryos Prior to the Appearance of Intersomitic Clefts.—(Plate

XXII, Fig. 1.) Toward the end of this period when the axial mesoderm

has thickened and is on the point of becoming segmented, the medullary

plate (5)? is represented by an oval thickening of the ectoderm which

peripherally passes into the somatic ectoderm (7) by a gradual transition

(28) without clearly defined limits. In some of our embryos there were

irregular depressions and elevations of the surface, especially in its lateral

regions, which presented some resemblance to the Seitenfurche, Rand-

furche and Parietalzone of authors, but which, in view of the uniform

outlines of the excellent embryo here figured, we have not been able to

convince ourselves were natural structures.

Embryos of One Somite——(Plate XXII, Fig. 2.) In these embryos

one pair of complete intersomitic clefts is present. In addition, the

axial mesoderm presents on each side two or three transverse constrictions

which are evidently due to the inception of somites. In the cat it appears

that several somitic constrictions are imitiated simultaneously. In our

reckoning we have regarded only the complete clefts and the number of

somites assigned to the embryos of our series are estimated in terms of

complete clefts. In the two embryos which we have classed as having

one pair of somites there are, in addition, two or three pairs of con-

strictions, one pair of which is situated in front of the first complete

intersomitic cleft. The medullary plate (5) merges laterally into the

somatic ectoderm (7) by a gradual transition (28) as in the earlier

stages. Cephalad its axial region is depressed. We would call attention

to the fact that the summits of these incipient medullary folds corre-

spond to the middle zone of the medullary plate on each side.

Embryos of Two Somites.—(Plate XXIII, Fig. 1.) The medullary

plate has the same general characters as in the preceding embryos. It

is very broad and passes by gradual transition (28) into the somatic

ectoderm (7) at the sides. Craniad the medullary groove is somewhat

2The numerals in italics refer to the numbers of the leaders in the figures.

322 ANNALS NEW YORK ACADEMY OF SCIENCES

deeper and the medullary folds have partially erected themselves over

a greater longitudinal distance. Craniad also a faintly marked furrow

is present in the region where the medullary plate becomes thinner as

the somatic ectoderm is approached. In addition, the lateral region of

the plate presents slight undulations of the surface.

Embryo of Three Somites—(Plate XXIII, Fig. 2.) The neuraxis

has the same general configuration as in the preceding embryos. The

boundary between the medullary plate (5) and the somatic ectoderm

(7) is still effected by a gradual transition (28). Craniad there is a

faint furrow as in the embryo of two somites, and in this region also

the margin is marked by faint undulations.

Embryo of Four Somites—(Plate XXVII, Fig. 1; Plates XXIV-

XXVI.) The neuraxis has not lengthened appreciably as compared with

the embryos of three and of two somites. In its cranial half, however,

the neural folds (5) have fully erected themselves and an abrupt bound-

ary has been established between them and the somatic ectoderm (7).

Caudad this junction is still effected by a gradual transition; there is

no furrow. The floor plate terminates craniad in a distinct thickening

and elevation (2) which intervenes between the ventral extremities of

the optic sulci (1). In front of them it is continuous with the ectal

margins of the primitive optic vesicles. We have designated this eleva-

tion the tubercle of the floor. The optic sulci begin on each side of the

tubercle of the floor where they are continuous with the angle that defines

the floor-plate from the parieties. They describe an are with the con-

cavity caudad and approximately parallel to the margin of the neural

plate, but approaching the neurosomatic junction and becoming fainter

as they are followed caudad. Corresponding to their arched segment

there is a marked thickening and external prominence of the wall of the

neural tube.

At a short distance caudad to the optic sulci there are a pair of similar

though shallower furrows, close to the neurosomatic junction. Their

course is at first horizontal; their caudal portions turn ventrad and

approach but do not reach the floor-plate. Corresponding to their hori-

zontal portion, there is a ridge-like projection between the summit of

the neural plate and the somatic ectoderm. This ridge is the quintal

anlage (3). That it is more intimately related to the neural fold (5)

than to the somatic ectoderm (7) is shown both by the fact that the

neurosomatic junction is dorsal to it and by the fact that it blends at

both of its extremities with the thickened dorsum of the neural plate.

It is in no sense an element intermediate between neural plate and

ectoderm. Just behind the quintal anlage is another, smaller furrow

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 323

(4) which is not accompanied by any definite local protrusion of the

wall but simply grooves the medullary fold entally near the neurosomatic

junction, becoming broad and shallow and disappearing before the floor-

plate is reached. This furrow corresponds to the acoustico-facial anlage

in older embryos. We would note further that on the right side there

is a small pit situated midway between the optic and quintal sulci having

the same characters as the latter, except that it is unaccompanied by an

external protuberance and is present only in three sections of 13.3 micra

each. This had no homologue on the left side. It is possible that this

minute furrow represents the profundus anlage, although clear evidence

of its presence is not found in our embryos until the stage of twelve

somites is reached. A similar conformation was observed farther caudad

on the left side in the region behind the last somite; it extended over

three sections. Caudad the medullary folds divaricate and become lower,

eventually disappearing in the region of the primitive groove. In con-

trast to the cranial extremity, it is to be noted that here the first portion

elevated is the lateral and not the basal zone of the medullary plate.

This is characteristic of this region in later stages as well. It is ap-

parent, therefore, that, both craniad and caudad, the elevation of the

neural folds is accomplished in two phases but that the order of events

is reversed at the two ends of the embryo. Craniad the basal region

first becomes vertical, then the lateral, while caudad the converse is true.

This is the only evidence we have been able to find of a morphologic

difference between the basal and alar plates, for the sulcus limitans is a

late formation, if it is present at all in young embryos of the cat.

Embryos of Seven Somites.—The neural folds are separate in their

entire length and in general show but little advance in comparison with

the embryo of four somites. The optic sulci are strongly arched and the

prominence of the primitive optic vesicles is slightly increased. The

tubercle of the floor intervening between the two optic sulci forms a well

defined cranial limit to the floor of the neural tube, and blending with

the wall in front of the optic sulci forms the ventral lip of the neuropore.

The quintal and acoustico-facial sulci consist of horizontal and obliquely

descending segments, the latter in each case becoming broader and shal-

lower as they approach the floor-plate. On the ectal surface of the neural

plate faintly marked oblique elevations correspond to the oblique portions

of these sulci. The quintal anlage forms an elongated ridge, extending a

little farther craniad than the horizontal segment of the quintal sulcus.

Its extremities now project free of the medullary plate, no longer fusing

with it as in the embryo of four somites. This anlage enters into inti-

mate relations with the mesenchyme of the head, the two tissues passing

324 ANNALS NEW YORK ACADEMY OF SCIENCES

into one another by such gradations that it is difficult and in some sec-

tions impossible to determine the precise limits of the ganglion.

Embryos of Hight Somites—(Plate XXVII, Figs. 2, 3; Plates

XXVITI-XXX.) While the neuraxis shows little if any increase of length

in comparison with the preceding embryos, the closure of the neural folds

has been initiated. This is first effected*in the region immediately in

front of the quintal anlage (3), where the folds obtain their greatest

height (embryo No. 586). In embryo No. 530 there is an additional

point of closure immediately caudal to the quintal anlage.

The optic sulci (7) have increased in depth and the optic vesicles form

prominent, ellipsoidal projections with nearly vertical axes. Evidently

they correspond to the arched segments of the optic sulci in the younger

embryos; the horizontal caudal continuations of these furrows are now

reduced. Caudal to the optic vesicle the wall of the neural tube is flat

until near the quintal anlage (3), where a moderate dilation is present.

This ganglion has now a triangular form and is shorter than in the pre-

ceding embryos. It is attached to the dorsum of the medullary plate

near its Junction with the somatic ectoderm, corresponding to the inter-

val between the two points of closure of the neural tube (embryo No. 530)

and at the summit of a shght constriction intervening between two mod-

erate dilatations. The first of these dilatations (37) has already been

mentioned; the second (12) corresponds to the oblique descending por-

tion of the quintal sulcus, which as a whole in these embryos is under-

going reduction. The acoustico-facial ganglion (4) is small and has a

shallow corresponding sulcus. The ganglion occupies the summit of a

constriction immediately behind the quintal dilatation and is followed

by a slighter enlargement (73) of the tube, into which its sulcus merges.

It is then, in its sulcus and following dilatation, a repetition on a smaller

scale of the quintal anlage. The common ganglionic crest extends from

the acoustico-facial ganglion, with which it is continuous to the level of

the fourth pair of mesodermic segments. In the caudal half of the neu-

raxis the neural folds are lower; at first parallel, they diverge in the region

of the rhomboid fossa (21). Here the neural plate of each side comprises

a horizontal mesial region, and a smaller lateral erected portion, the two

meeting at a rounded angle. In the midline there is a vestige of the

primitive groove (6).

Embryo of Nine Sonites—(Plate XXXI.) The closure of the neural

tube is advancing rapidly. It is not, however, effected by a uniform ad-

vance in both directions from the region of earliest closure, but on the

contrary is incident at several separate points of the neuraxis, as was fore-

shadowed in the eight-somite embryo. In addition to the anterior neuro-

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 395

pore (8), there are three small gaps (9) in the region of the quintal

anlage (3) corresponding to the hiatus there present in the embryo of

eight somites. Another small orifice (10) is situated in the region of the

acoustico-facial anlage (4). Caudal to this the folds unite for a consid-

erable distance but again separate (71) in the region of the fourth to the

eighth somite; opposite the ninth they are again united for a short dis-

tance when they finally separate and diverge.

The anterior neuropore is markedly diminished in extent. That this

is caused by closure at its ventral as well as at its dorsal lip is shown by

a comparison of the models in Plate XX VII, Fig. 3, and Plate XXXI,

Fig. 2. In the eight-somite embryo the optic vesicle is open in its whole

extent; in that of nine somites closure has been effected in about half of

its length. The prosencephalon shows a distinct advance beyond that of

the eight-somite embryos both in size and in the complexity of its surface

relief. It projects strongly ventrad, its caudal margin forming approxi-

mately a right angle with the floor of the neural tube. It is demarcated

from the midbrain by a shallow anterior isthmian sulcus (22) which is

very obliquely inclined. The optic vesicles form its ventro-cranial region ;

they are somewhat pyriform with a pointed caudal extremity and their

long axes are inclined at an acute angle with the horizontal. Dorsally

the optic vesicle is defined by a shallow depression; between this and the

anterior isthmian sulcus are two small elevations, one on the dorsal and

one on the ventral aspect of the tube. The dorsal eminence is the thala-

mencephalon (Plate XXXI, Fig. 2, 76) and is opened in its whole length

by the neuropore. It is somewhat triangular in shape and its prominence

diminishes ventrad where it is separated by a faint depression from the

ventral eminence. This latter also has a triangular shape and is the first

indication, in our series, of the mammillary region (Plate XXXI, Fig. 2,

17). Ventrally it is separated from the pointed extremity of the optic

vesicles by a slight incisure which corresponds to a thickening and an in-

ward projection of the floor-plate. As this is interposed between the

ventral extremities of the optic sulci, it is evidently the tubercle of the

floor (Plate XXXIX, Plate XL, Fig. 1, 2) of the earlier stages. The de-

pressions defining the thalamencephalon and the mammillary region form

an H-shaped system of furrows, while the two elevations taken together

form a segment which separates the primitive optic vesicles from the mid-

brain. That this segment is not a neuromere in any precise sense of the

term is obvious from its developmental history, for the two eminences of

which it is composed fuse only at a considerably later period (sixteen

somites). The prosencephalon lies immediately in front of the foregut

and the entoderm is closely applied to the mammillary region. A com-

326 ANNALS NEW YORK ACADEMY OF SCIENCES

parison with the embryos of eight somites makes it evident that these

changes are not wholly to be attributed to inequalities of growth, but that

a profound remodeling of the cranial extremity of the neuraxis has taken

place in addition, as is shown by the alteration in the direction of the

optic axes, the inclination of the anterior isthmian sulcus and in the

notable lengthening of the midbrain taken, in connection with its dimin-

ished height. i

Embryos of Ten Somites—(Plate XXXII.) The union of the neural

folds has progressed. The anterior neuropore (8) extends through the

greater part of the length of the optic vesicles into the thalamencephalon

(16), the somatic ectoderm being further adherent as far as the mesen-

cephalon (15). In this segment of the brain and for a considerable dis-

tance caudad the folds have closed and the neural tube has separated

from the ectoderm. The roof-plate is concave and depends into the lumen

as a longitudinal ridge. Somewhat in front of the middle of the neu-

raxis there is a considerable hiatus in the line of closure of the neural

folds and behind this are three small areas in which the ectoderm is still

adherent, though closure has been completed (1/7). The fossa rhom-

boidalis (21) falls into two portions of about equal length. Cephalad it

is narrow and the neural folds are high, approximated and nearly paral-

lel. The caudal region is broad and bounded by low folds erected only

in their lateral parts; here the neural plate still passes into the somatic

ectoderm by a gradual transition.

The prosencephalon joins the rest of the neuraxis at an acute angle.

The anterior isthmian sulcus (22) is horizontal with ventral concavity.

The mammillary region (17) is well marked, as is also the thalamen-

cephalon (16); the axis of the optic vesicle is horizontal. A posterior

isthmian sulcus (23) defines the midbrain caudally. In embryo No. 476

this vesicle is obscurely divided into two segments by a shallow furrow.

The hindbrain has three recognizable segments; the first (31) is trian-

cular with its base ventral; the second (72) and third (73) are obliquely

inclined and defined by shallow, oblique furrows. The quintal anlage (3)

is attached in the interval between the second and third segments and

the profundus anlage between the second and first (Plate XXXII, Fig. 2,

$a). This is the youngest embryo of our series in which the profundus

element can definitely be made out. The acoustico-facial anlage (4) is

separated by a short interval from the quintal anlage: it occupies the

furrow which defines the third hindbrain segment caudally and is con-

tinuous with the ganglionic crest of the trunk (not shown in the model).

A second émbryo of ten somites (No. 532) corresponds closely to the

embryo just described, except for a somewhat greater degree of union of

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 39%

the medullary folds. The anterior neuropore is reduced to a minute ori-

fice situated ventrally at about the middle of the optic vesicles, thus

affording, in comparison with the foregoing embryo conclusive evidence

of progressive closure at the anterior lip of the neuropore and to this de-

gree depriving the orifice of value in determining the morphologic ceph-

alic extremity of the neural tube. Apart from this small opening the

anterior neuropore is closed, but the ectoderm is adherent over the cranial

portion of the optic vesicles and the adjacent region of the thalamen-

cephalon. The midbrain shows no sign of division into two segments.

Embryos of Twelve and Thirteen Somites—(Plate XXXIII.) These

embryos form a closely graded series, passing from the conditions de-

scribed in the embryos of ten somites to those attained by the fourteen

somite embryos of our series. In the region of the anterior neuropore

(S) they show a considerable degree of variation in the closure. In em-

bryo No. 534 of twelve somites, the neuropore has been completely closed.

The ectoderm is, however, adherent at the middle of the sagittal length

of the optic vesicles and further over the region of junction of optic vesi-

cle (1) and thalamencephalon (16). In embryo No. 86 of thirteen

somites, the ectoderm is adherent in the whole length of the optic vesicle

and there are three small orifices, one at the middle of the optic vesicle,

one at its junction with the thalamencephalon and one in the thalamen-

cephalon itself.

There are three oblique segments in the hindbrain; their interseg-

mental constrictions give attachment to the profundus (3a), quintal (3)

and acoustico-facial (4) ganglia in the order named cranio-caudad. The

acoustico-facial is continuous with the ganglionic crest (20) which ex-

tends for somewhat more than half the length of the neuraxis. Follow-

ing these oblique ganglionic segments is a series of vertical segments;

their constrictions corresponding to the mesodermic somites are six to

seven in number. It is thus seen that the vertical segments of the neu-

raxls correspond in location to the somites, but lag considerably behind

them in number, which we take to mean that an interval in time elapses

between the formation of the mesodermic somite and formation of the

corresponding myelomere. It seems to us, therefore, that ontogenetically

myelomeres are secondary to the mesodermic somites. The three oblique

hindbrain segments, associated with the three large ganglia, are situated

in advance of the somites. We would emphasize the difference in their

disposition as evincing their independence of the myomeric segmentation.

Embryos of Fourteen Somtes.—(Plate XXXIV.) The two embryos

of this stage in our series show a close correspondence in the neuraxis,

save only that embryo No. 548 is in most respects slightly in advance of

328 ANNALS NEW YORK ACADEMY OF SCIENCES

its fellow, No. 188. The neural folds are united, except in the short,

narrow rhomboid fossa, in the caudal portion of which the neural plate

still passes by a gradual transition into the somatic ectoderm. The an-

terior neuropore (8) has closed, but the ectoderm is still adherent from

the middle of the optic vesicle to the thalamencephalon. Embryo No.

188 is more advanced in this respect, for the ectoderm is free of the

neuraxis in the whole length of the prosencephalon. It is, however,

adherent in the midline from the level of the profundus anlage to that

of the acoustico-facial ganglion. A comparison of these two embryos

affords a striking example of the irregularity incident to the whole

process of closure of the neural tube and its separation from the ectoderm

in the cat, and seems to justify the attachment of less importance than

is usually ascribed to the point of ultimate closure. The neuraxis is

bent ventrad at the posterior isthmian sulcus (23). This is the second

actual flexure observed in our series, for a comparison with the figures

of the preceding embryos shows that the earlier projection ventrad of

the prosencephalon was associated with a remodeling of the midbrain

and an inclination of the anterior isthmian sulcus, while in the stage

now under discussion the bend is accentuated at the posterior isthmus.

The hindbrain forms a gentle arch passing into the straight myelenceph-

alon. In the forebrain important new conditions are initiated. The

optic vesicle (7) is now not only relatively but absolutely smaller than

in the younger embryos and an ectoptic zone begins to emerge from its

periphery. As yet these changes are conspicuous only dorsally between

the optic vesicle and the thalamencephalon (16), and to a less degree

ventrad immediately in front of the mammillary region (17). The

dorsal element is the telencephalon (19), the ventral corresponds in

general to the infundibular region (18). The mammillary region and

the thalamencephalon have increased in size and form well-marked tri-

angular prominences in lateral view. The midbrain (15) is a well-

marked dilatation, triangular in form, defined by conspicuous isthmian

furrows (22, 23) which all but meet ventrally in the angle formed by

the second flexure of the neuraxis. The arched form of the hindbrain

has been mentioned ; its vertical diameter is increased by a ventral pro-

jection at the level of the quintal ganglion (3), the pontine angle. Thus

it appears that a projection of this region long antecedes the develop-

ment of the pontine flexure. In lateral view, the three segments with

their oblique separating furrows are more conspicuous than in the younger

embryos. ‘They are especially prominent ventrad, which would seem to

imply that their increasing definiteness is associated with the bending of

the hindbrain. The ganglia are attached dorsally in the furrows; the

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 329

profundus (3a) between the first and second segments (3/7, 12); the

quintus (3) between the second and third (12, 13) ; the acoustico-facial

(4) immediately behind the third. Ventrally the second segment shows

signs of subdivision. Barely seen in embryo No. 188, in No. 548 it is

marked by a vertical furrow ascending to the attachment of the quintal

ganglion and dividing the segment into an oblique cranial portion (12a),

extending completely across the neural tube and a triangular caudal

fraction (12b) which forms the bulk of the pontine angle but is confined

to the ventral region of the neural wall, being excluded from, the alar

portion by the oblique complete third segment. The myelencephalon has

seven neuromeres. ‘These contrast sharply with the foregoing by their

vertical position. The oblique metencephalic segments are now con-

tinuous with the neuromeres of the myelencephalon:; that they form a

homodynamous series is certainly not supported by the evidence of their

development in the cat, in fact the heterogeneity of these elements seems

as clearly given by their ontogeny as by the diversity of the peripheral

nerves with which they are associated in the adult.

Embryo of Sixteen Somites——(Plate XXXV.) The neural tube is

closed and completely separated from the ectoderm except in the region

of the fossa rhomboidalis. The flexure at the posterior isthmian sulcus

(23) has increased and the nuchal bend is now present. In the hind-

brain the region of the second (12) segment projects ventrally and

forms the pontine angle. The optic vesicles (1) are still further reduced

in size, absolutely as well as relatively, and there is formed both ventral

and dorsal to the vesicle a considerable zone which represents the exten-

sion of the telencephalon (19) and infundibular region (18) of the

preceding embryos. The coalescence between the mammillary region

(17) and the thalamencephalon (16) has increased; and they now form

a well-marked segment between the midbrain and the derivatives of the

optic vesicles (1).° The mesencephalon (75) is triangular and markedly

compressed ventrad. The segments-of the hindbrain are less oblique

than in preceding embryos. The first (31) is large, the second (12a.

12b) forms the prominence of the pontine angle, is ventrally subdivided

and its second segment now extends farther dorsad. The third segment

(13) is narrow. The ganglia retain their primitive intersegmental po-

sitions.

Embryo of Seventeen Somites.—(Plate XXXVI.) The reduction of

the optic vesicle (1) continues. The telencephalon (19) forms a promi-

*In this respect this embryo corresponds closely to the four-millimeter sheep embryo

figured by Neumayer—Studien zur Entwickelungsgeschichte des Gehirns der Saiiger-

thiere. Festschrift zum Siebenzigsten Geburtstag von Carl von Kuppfer. Taf. XLVIII,

fig. 4. Jena, 1899. ;

330 ANNALS NEW YORK ACADEMY OF SCIENCES

nent convexity in front of the optic vesicle. Near its upper limit there

is a point where the ectoderm is still adherent (S). The area which we

have termed infundibular region (78) is very large and has a pointed

apex directed. caudad. The mammillary region (17) has increased in

size but otherwise closely resembles that of the fourteen somite embryos.

The same is true of the mesencephalon (14). The hindbrain is markedly

enlarged in its vertical diameter. The pontine angle has increased in

prominence. ‘The first hindbrain segment (32) is broad and prominent ;

the second (12) is subdivided by a deep sulcus; its posterior moiety

(12b) has a considerable vertical extent but is now fusing dorsally with

the third segment (13) which remains narrow but has increased greatly

in height, forming indeed the apex of the pontine angle. The quintal

ganglion (3) retains its intersegmental position, but that of the pro-

fundus (3a) is beginning to shift caudad and is now in part attached to

the second segment (12a). The cranial extremity of the myelencephalon

has increased markedly in vertical diameter and is beginning to be

assimilated to the hindbrain; it shows a prominence of the roof at its

commencement which is separated by a depression from the remainder

of the roof-plate. This embryo showed some degree of side-to-side com-

pression with resulting diminution of the relief of its lateral walls and

an exaggeration of the projections in the dorsal and ventral midline.

Embryo of Nineteen Somites.—(Plate XXXVII.) The forebrain is

defined by a well marked anterior isthmian constriction (22) which is

practically in line with the venter of the hindbrain. The thalaman-

cephalon (16) has enlarged and is separated from the telencephalon (19)

by a shallow but definite furrow (26) extending from the dorsal mid-

line, obliquely over the lateral surface of the brain to the depressed area

immediately behind the optic vesicle where the thalamencephalon merges

into the relief of the regio mammillaris (77). The latter has not increased

in size and is separated from the regio infundibularis (178) by a shallow

furrow ; it is also distinguished by its greater lateral prominence. The

remainder of the forebrain comprises the optic vesicles and an ectoptic

zone surrounding them. ‘The latter has greatly enlarged in its dorso-

cephalic portion, the telencephalon (19), which now forms the extremity

of the brain. The regio infundibularis shows but a moderate increase

in size. New conditions are initiated ventral to the optic vesicles, which

now begin to retreat from the margin of the brain, leaving a narrow

strip of tissue through which the infundibular region and telencephalon

are continuous. This condition is more clearly shown in the model of

the lumen.

The midbrain (75) is little changed as yet but is beginning to show

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 3231

a lengthening of its dorsum which becomes marked and characteristic

in later stages. In the hindbrain the pontine angle has increased in

prominence. The first segment (31) is very large, the second (12) is

ventrally subdivided into two, as is also the third (13). The sulci

corresponding to these subdivisions extend dorsad only so far as the

ganglia. Behind the third of the original segments of this region is

one small projection confined to the ventral portion of the neural tube.

This is followed by the vertical myelomeres corresponding to the meso-

dermic somites.

The large ganglia are shifting their points of connection with the

neural tube and are now attached somewhat above the middle of its

lateral wall. The profundus (3a) has shifted to the middle of the

second segment, lying at the extremity of the sulcus which marks its

ventral subdivisions. ‘The quintal ganghon (3) has lost its primitive

intersegmental position and adheres to the cephalic part of the third

segment. These two ganglia are thus beginning to approach one an-

other. The acoustico-facial (4) occupies the interval between the fourth

segment (14) and the first myelomere (24).

Embryo of Twenty-one Somites.—(Plate XXXVIII.) The forebrain

differs from that of the preceding embryo notably in the enlargement

of the infundibular region (1S) as well as in the increase of the ectoptic

zone as a whole. The optic vesicles have receded further from the

ventral margin and a broader strip connects the infundibular region

with the telencephalon (79). The ectoderm is adherent to the latter

at a point corresponding to the somewhat angular junction of the ventral

and cranial margins of the pallium. On either side of this line of

adherence the neural tube gives rise to projections (27), not quite sym-

metrical, which bear the same relation to the medullary plate as the

large ganglia at their inception. The element of the right side, which

is somewhat the larger, contains in its interior two small cavities which,

however, do not communicate with the lumen of the neural tube. We

are unable to offer any suggestion as to the significance of this structure,

nor have we found in younger or older embryos of the cat any corre-

sponding structure.

The thalamencephalon (76) and mammillary region (17) together

form a well-defined segment of triangular outline interposed between

the foregoing structure and the midbrain (15). The latter shows an

increase of length in its dorsal zone. The hindbrain differs but little

from that of the preceding embryo. Its first segment (37) is somewhat

compressed ; the second (12) is subdivided ventrally and the profundus

ganglion (3a) is attached at about its vertical middle, close to its caudal

332 ANNALS NEW YORK ACADEMY OF SCIENCES

margin. ‘The third segment is also subdivided ventrally ; the attachment

of the quintal ganglion (3) extends close to its cranial border. These

two ganglia are thus approximated and on the point of union which is

ultimately effected in embryos of twenty-six somites. The third seg-

ment is followed by a slight prominence (1/4) confined to the ventral

region of the neural tube and less clearly marked off from the myelen-

cephalon than in the preceding embryo. Above it is the acoustico-facial

ganglion (4). The relief of the following neuromeres is faint and to

be made out only with great difficulty in this embryo. The model of

the lumen (Plate XLI) corroborates the description we have given of

the external relief, but in addition presents one or two details which are

not perceptible from the surface. The plica ventralis encephali by its

broad summit forms the floor of the midbrain. Its anterior angle, the

tuberculum postero-superius of authors, juts forward prominently. Im-

mediately below is the recess of the mammillary region (17) bounded

ventrally by the tuberculum postero-inferius (2). Ventral to this again

is the large triangular cavity of the infundibular region (18). Its

ventral wall shows a moderate thickening, torus postopticus, in front of

which is the shallow preoptic recess, from which the lamina terminalis

extends forward and upward to a point at which the ectoderm (7) is

adherent.

We have now completed the record of our objective findings on the

basis of which we propose to discuss the problem stated in our opening

paragraph ; we shall endeavor in the course of this discussion to compare

our results with those of other students only in so far as they have dealt

with mammalian embryos of corresponding stages of development. Un-

fortunately the number of detailed descriptions of such embryos is not

large. We have not, therefore, attempted any general comparison of

the ontogeny of the mammalian neuraxis with that of better known

forms, except in a few instances when it has a direct and important

bearing upon our problem.

GANGLIONIC CREST

It has already been stated that the medullary plate primitively lacks

a precise boundary and passes by a gradual thinning into the somatic

ectoderm (Plate XXII, Fig. 1, 28). Prior to closure, however, and this

is true of the head as well as the trunk, an abrupt demarcation is estab-

lished and the somatic ectoderm joins the medullary plate at its dorso-

median angle (Plates XXVITI-XNXX). This remodeling of the neuro-

somatic junction is progressive cephalo-caudad, and is completed in each

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 33:

region before closure occurs. Coincidently the medullary plate narrows

markedly so that it is probable that the primitive region of transition is

thinned out and added to the somatic ectoderm. When closure is effected

the ectoderm is closely apphed to the concave dorsum of the neural tube

and is continuous from side to side, without median attachment to the

neuraxis, and with no intervening cells (Plate XLI). We would empha-

size these facts, for they patently exclude the interpretation of the gang-

lionic crest of the trunk as an element intermediate between the general

ectoderm and neural tube, and primitively independent of the latter. In

this point our observations are in accord with the sections of the cat fig-

ured by Fleischmann‘ and of the human embryo by Felix’ and agree with

Neumayer’s® observations upon the trunk region of reptiles. It would

seem to follow, therefore, that the ganglionic crest of the cat is a deriva-

tive of the neural tube, and this view acquires an antecedent probability

from the occasional retention of afferent ganglion cells in the neuraxis of

the adult, as in Amphioxus and Teleosts, and in the mesencephalic root

of the trigeminus of mammals. |

In the cat, the ganglionic crest is formed in the trunk by a simple

delamination of the dorsal less regularly arranged cells at the summits

of the neural folds. Shortly after closure a minute cleft appears on

each side and advances towards the midline, until the crests are attached

only by a narrow median strand. Again our results are concordant with

those of Neumayer for reptiles.

Sometimes, and not always symmetrically, prior to closure, a faint

furrow appears on the ental surface of the neural fold close to the junc-

tion with the somatic ectoderm. This we have taken to indicate some

small degree of lateral movement of the cells at this point as though to

form an evagination. The process is abortive but suggests that in the

derivation of the ganglionic crest from the neural tube delamination

may have been substituted for evagination, and a solid anlage may have

replaced a hollow one, as elsewhere in the ontogeny of forms rich in cells.

Farther cephalad the evagination becomes conspicuous. In the acous-

tico-facial region (Plates XXVI and XXX) there is a shallow oblique

furrow unaccompanied: by evagination and the ganglion seems to agree

* A, FLEISCHMANN: Embryologische Untersuchungen. Erstes Heft. Taf. II, figs. 4-6;

Taf. III, figs. 3-12. Wiesbaden, 1889.

°W. FELIX: “Die Entwickelung der Harn und Geschlechtsorgane in Keibel and Mall,”

Handbuch Entwickelungsgeschichte des Menschen. Figs. 522, 525, 528-530. 1911.

®°L. NEUMAYER: “Zur Morphologie des Central Nervensystems der Chelonier und Croco-

dilies.” Aus Voeltzkow Reise in Ostafrika in den Jahren. 1903-1905. Band IV. 1914.

Uber den Schluss der Sekiindaren Medullarfurche und die Genese der Neuralleiste. Ver-

handl. Anat. Ges. 22. 1913. ‘‘Histogenese und Morphogenese des peripheren Nerven-

systems, der Spinalganglien und des Nervus sympatheticus.”. Handbuch der Vergleich,

und experiment. Entwickelungslehre der Wirbelthiere. Hertwig- 1906.

334 ANNALS NEW YORK ACADEMY OF SCIENCES

with the more caudal-ones in owing its origin to delamination from the

medullary fold.

In the quintal anlage the sulcus is conspicuous and its horizontal por-

tion is associated with a ridge-like projection (Plates XXV and XXIX)

in the angle between neural plate and somatic ectoderm, which yet

reveals its closer affinity to the neural plate by blending with it at both

of its extremities in the four-somite embryo. It then appears subtended

by a longitudinal furrow, and differs more in size than in any essential

character from the more caudal ganglionic crest.

Finally, the optic vesicle, a pure evagination, presents at an early

stage much resemblance to the quintal anlage (Plates XXIV and

XXVIII), from which it differs chiefly in size and in the more ventral

position of its sulcus.

We see in these anlages a series of structures, passing by gradations

from the delaminated ganglionic crest through the acoustico-facialis and

quintus to the optic vesicle, which is formed by evagination alone. It

seems to us, therefore, that the primitive neural plate in the cat gives

rise both to the neural tube and to the ganglionic crest, the latter being

a derived and secondary element and not a codrdinate intermediate be-

tween the medullary plate and the somatic ectoderm. In the forebrain

elements equivalent to the ganglionic crest are retained in the wall of

the vesicles and constitute the dorsal region of the neural plates, for if

the crest secondarily separates from the neural tube, in regions where

such separation fails to occur, it is more probable that the crest is in-

cluded in the brain than that it has been absolutely suppressed. Ac-

‘cordingly. the analysis of the prosencephalon is not to be a'tempted in

terms of the basal and alar plates alone, as has been customary since His,

but must inciude a dorsal or ectal strip equivalent to the ganglionic crest

along its conveai y, and this must include at least as much of the brain

wall as lies ectal to the optic sulcus. This ganglionic element (the

primitive optic vesicle) at four somites forms the cephalic extremity of

the neural fold, and arches ventrad to the floor. If our argument is

correct, the optic vesicle and the ectoptic structures, whether above, in

front or below the optic region, must be considered of ganglionic equiva-

leney, a conclusion which entails a revision of His’s analysis of the brain.

The question of the substitution of mesectoderm for a neurogenic

ganglionic crest in the prodtic region in mammals can hardly, we believe,

receive an affirmative answer in view of the conditions observed in the

eat, for we find quite generally the separation between ectoderm and

neural tube clean cut, and the space between these structures unoccupied

by cells. The mesectoderm of the ichthyopsid and sauropsid embryo,

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 335

described by Neal,’ Johnston,* Neumayer,® and others, is, perhaps, not

altogether fortunately designated ganglionic crest, for these investigators

describe it as taking origin from an intermediate element, interposed

between neural tube and ectoderm and derived from both of these

structures. On the other hand, the ganglionic crest in the trunk in

sauropsids (Neumayer) as well as in the cat is a derivative from the

neuraxis, as in the latter form are also the cranial ganglia. It would

seem, therefore, that having slightly different derivations the mesecto-

derm and the ganglionic crest ought not absolutely to be homologized.

Neumayer has formulated this standpoint clearly, as follows:

“So zeigt sich im Aufbau des cerebralen Teiles der Ganglienleiste, soweit sie

dem Archencephalon und dem praeédtischen Gebiet des Hirns angehdort, ein

Verhalten, das sich morphogenetisch wesentlich von den einfacheren Verhialt-

nissen im postotischen und spinalen Gebiet unterscheidet. Ich kann mich tiber

die Vorgiinge hier im Anschluss und die oben (p. 452) gemachten Angaben in

Kiirze fassen. Entsprechend dem im spinalen Gebiete anders erfolgenden Ver-

schlusse des Medullarrohres wird das zum Aufbau der Ganglienleiste notwen-

dige Zellmaterial bei Crocodilus madagascariensis und Emys lutaria nur yom

Dache der Medullaranlage geliefert; die so entstandene postotische Ganglien-

leiste ist demnach wesentlich verschieden von der cerebralen praedtischen. Sie

entbehrt des primiiren, aus Exoderm und Medullarwand entstammenden An-

teils und enthilt nur jene Elemente, welche in die cerebrale prae6dtische Gang-

jienleiste sekundir eintreten.

“Hiehzu kommt auch ein Unterschied in den Leistungen der beiden Gang-

lienleisten: von ihnen liefert die cerebrale, praedtische in gleicher Weise Ner-

ven und mesodermales Gewebe fiir das priiotische Kopfgebiet, wiihrend das

spinale, postotische Ganglienleistensystem einzig Nervengewebe aus sich her-

vorgehen lisst.”

In the cat, the paraxial mesoderm of the head is abundant and very

early becomes loosely arranged, extending dorsad and forcing its way

into the cleft between the ectoderm and the dorsum of the neuraxis.

We have stated that at the time of separation of these two structures,

their demarcation was sharply defined and without intervening cells, nor

were we able to find mesoderm at any time in this situation, which was

not continuous ventrally with the general mesoderm of the head. This

lack of evidence of the formation of mesectoderm in the cat inclines us

strongly to accept Neumayer’s distinction of a primary and secondary

prootic ganglionic crest, the former (mesectoderm) being undeveloped

7H. V. NEAL: “‘The Segmentation of the Nervous System in Squalus Acanthias,’ Bull.

Mus. Comp. Zool. Cambridge, Mass., Vol. XXXI, No. 7. 1898.

§J. B. JOHNSTON: The Nervous System of Vertebrates. Philadelphia, 1906. ‘The

Morphology of the Forebrain Vesicle in Vertebrates,’ Jour. Comp. Neurol. and Psychol.,

Vols XIX, No. 5: 1909.

®L. NEUMAYER: Op. cit., 1914, p. 460.

336 ANNALS NEW YORK ACADEMY OF SCIENCES

in the cat, the latter arising from the neuraxis by delamination com-

bined with the evagination constitutes the cranial ganglia, and at the

extreme cephalic pole, failing, we believe, to separate remains incor-

porated as the primitive optic vesicle.

CLOSURE OF TITLE NEURAL ‘TUBE

At the extremities of the axis the elevation of the neural folds may

be resolved into two acts. Cephalad the median or basal portion is first

elevated, while laterad the plate has still a horizontal direction. This

condition is present in the embryos of two and three somites (Plate

XXIII, Fig. 2). The condition seems to be the effect of modeling of

the ectoderm upon the paraxial accumulation of mesoderm. At four

somites (Plate XX VII, Fig. 1) the fold is erect in its whole extent and

rises well above the mesoderm, the somatic ectoderm being closely apphed

to the neural plate in its dorsal half. Caudad the process differs; the

lateral part of the plate is first elevated at some distance from the median

line (Plate XX VII, Fig. 1, and Plate XX VII, Fig. 2) and forms a low

wall for the broad rhomboid fossa. When the tube closes here, its diam-

eter is much less than the width of the fossa would lead one to expect.

This is suggestive of the possibility that the lengthening of the tube is

not due alone to axial growth, but may be assisted by a rearrangement

of the material of the neural plate in the sense of a shift towards the

median line so that the plate is extended caudad as it narrows. The

elevation of its lateral margins is associated with the moderate entypy

of the blastoderm and the early completion of the amnion at lis caudal

end.

The neural folds first meet in the region of the future mesencephalon,

but their closure is not simply progressive from this point in both

directions. On the contrary, it is incident simultaneously at several

points which may be rather widely separated. In the eight-somite

embryo, in addition to the closure of the midbrain, which extends from

the optic anlage to the quintal ganglion, there is a second closure be-

tween the quintal and acoustico-facial anlages ; and again, after an inter-

val, at a third point the folds seem on the verge of meeting (Plate

XXVIII, Fig. 2). There is also some fusion cephalad at the ventral

margin of the neuropore. This is of some theoretical importance and

diminishes the significance of the neuropore as a morphologic landmark.

The gaping of the tube in the region of the optic and quintal anlages

suggests that such structures in some way delay closure, but as the

neurosomatic junction is now sharply defined, it is difficult to believe

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 334

that this is in the interests of a hypothetical inrolling either here or in

the optic vesicles.

At nine somites the neuropore is shorter, by reason of closure at both

its ends but chiefly caudad. Its extremities now lie in the same vertical

plane. The quintal hiatus is closed at two intermediate points, present-

ing three small orifices (Plate XXXI, Fig. 1). Caudad to it a short

segment of the tube has closed. A small hiatus is present in the region

of the acoustico-facial ganglion. This embryo, therefore, gives addi-

tional evidence of the retardation of closure in regions of large ganglia.

Further irregularities are shown in Plate XXXII, Fig. 1, and Plate

XXXII, Fig. 1, in the trunk region, and in Plate XXXIII, Fig.-2,

and Plates XXXIV-XXXVI in the anterior neuropore. As this latter

closes ventrally as well as caudally, and irregularly in the intermediate

portion, it seems difficult to consider that its region of latest obliteration

has any fundamental morphological importance or can at all properly

be used to determine the cephalic extremity of the neuraxis, which is

certainly deflected ventrad. Further, if the wall of the neural tube is

divided into basal and alar plates, its cephalic pole ought to be the most

cephalic point in their line of union, 7. e., in the terminology of His,

the cephalic extremity of the sulcus limitans, when this sulcus can be

recognized. It would seem, therefore, that wherever this point is local-

ized it cannot be situated in the raphé which throughout its length is

assumed to be a suture between the summits of the alar plates, or, if

our interpretation prove correct, in the forebrain, between retained gang-

lionic zones. ‘To accept the last point of attachment of the ectoderm

marked by the recessus neuroporicus as the extremity of the axis, imphes

that the raphé below this point is a suture between the basal plates,

although it has never been shown that they were primitively cleft;

further it would seem the necessary consequence of the acceptance of

this landmark (recessus neuroporicus) that the mammillary and in-

fundibular regions and the ventral half of the optic vesicles themselves

were derived from the basal laminee. To accept the recessus neuroporicus

as the ontogenetic pole of the brain seems, therefore, to disregard the

ventral deflection of the neuraxis and° the composition of its wall of

basal and alar plates. In His’s three months’ embryo (No. 7 of Ziegler’s

series of models) the sulcus limitans passing forward in the midbrain

is continuous with a furrow which arches ventrad and reaches the mid-

line immediately in front of the oculomotor nucleus. This, we believe,

is actually the sulcus limitans demarcating the alar and basal laminz

and reaching the midline where the latter ceases to give evidence of its

existence, 7. e., immediately in front of the oculomotor nucleus, the most

338 ANNALS NEW YORK ACADEMY OF SCIENCES

cephalic structure which by its derivatives can be assigned to the basal

plate. A second furrow, not connected with the foregoing, extends

across the wall of the thalamencephalon, nearly horizontally, to the fora-

men of Monro. This sulcus of Monro, His interpreted as the continuation

of the sulcus limitans. The interpretation we have suggested is at least

as concordant with his observations and does not entail morphologic im-

possibilities. 7

In order to facilitate the comparison of these divergent interpretations

we subjoin two schemata; the first (Fig. 1) is based on the well-known

Fic. 1—Schema of the composition of the encephalon in terms of basal and alar plates

of His

1. Basal plate. 2. Alar plate. 3. Sulcus limitans.

figure of His; the second (Fig. 2) illustrates the region of the neuraxis

which must be assigned to the ganglionic crest on the basis of our in-

terpretation. We have retained from His’s figure the sulcus limitans

as it appears in later stages of development for the purpose of defining

the basal plate, although in the period of development of the cat covered

by our series of embryos this furrow is not even indicated.

PROSENCEPHALON

The elevation of the neural folds at their cephalic extremity is accom-

plished in two phases, affecting first their basal, later their alar portions

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 339

(Plate XXII, Fig. 2; Plate XXIII, Fig. 2, and Plate XXVII, Fig. 1).

The process is completed in the embryo of four somites. Two conspicu-

ous landmarks are now present—the tubercle of the floor and the optic

sulcus. Corresponding to the latter is a thick-walled evagination, the

optic vesicle (Plate XXIV). ‘This anlage resembles those of the quintal

and acoustico-facial ganglia and is peculiar only in the course of the

sulcus, which here approaches the floor at its cephalic and not its caudal

extremity, as in the case of the other ganglia. The tubercle of the floor

intervenes between the terminal portions of the optic sulci. Ventrad it

Fic. 2.—Schema of the composition of the encephalon in terms of basal and alar plates

and ganglionic zone

1. Basal plate. 2. Alar plate. 3. Sulcus limitans. 4. Ganglionic zone.

is in relation with the blind extremity of the foregut; the stomodeum

approaches, but hardly reaches it, from in front. By means of these

relations the tubercle is easily recognized in succeeding stages, when

ultimately it forms a transverse ridge intervening between the mam-

millary and infundibular regions.

The wall of the optic vesicle is divided by the sulcus into a ventral

portion adjoining the floor plate and an ectal zone extending to the

neurosomatic junction, and therefore forming the summit of the medul-

lary fold and later the lateral lip of the neuropore. Ventrally this zone

joins the tubercle of the floor, which so constitutes the ventral neuroporic

340 ANNALS NEW YORK ACADEMY OF SCIENCES

lip. It is obvious, but important to note, that the optic vesicle at this

stage forms the cephalic extremity of the neuraxis. Preoptic structures

in consequence must be derived secondarily, either from the ectal zone

of the optic vesicle, or by inrolling of somatic ectoderm at the neuropore.

Of the latter process there is no evidence in the cat, and this alternative

seems excluded by the abrupt character of the neurosomatic junction.

We may, therefore, confine our attention to*the optic vesicles and sum-

marize the changes by which they give rise to an ectoptic zone which

includes the anlages of the thalamencephalon, telencephalon and the

infundibular region. Most striking is the progressive and absolute re-

duction in size of the optic vesicles, which are actually smaller at the

stage of sixteen somites than they were at eight. Coincidently they cease

to occupy the whole vertical extent of the wall of prosencephalon and

become relegated to a ventral position. ‘The nature of these changes,

especially the reduction in size of the optic vesicle, permits of but one

interpretation, namely, that the ectoptic zone is formed at the expense

of the vesicle. A similar remodeling of the ventro-caudal portion of the

vesicle gives rise to the infundibular region.

As the tubercle of the floor constitutes the extremity of the floor-plate

and at the same time the primitive ventral lip of the neuropore, it is of

prime importance to ascertain its position in subsequent stages of de-

velopment. It is easily recognized by its thickness and its interposition

between the ventral ends of the optic sulci. At first, also, it is abutted

upon by the cul-de-sac of the foregut which, however, rapidly recedes

from it, at eight somites only reaching its caudal extremity and at ten

somites terminating beneath the midbrain.

In Plate XXXIX, Fig. 1, the ental surface of the brain is shown by

a mid-sagittal section of an embryo of eight somites. The tubercle of

the floor (2) forms the ventral lip of the neuropore: its cephalic ex-

tremity is connected with the suprasulecal portion of the optic vesicle of

each side. From the parieties it is separated by the shallow prolongation

of the optic suleus which terminates in a depression of the floor, imme-

diately behind the tubercle and above the foregut. There is, as yet, no

corresponding elevation of the ectal surface; the recess is the first evi-

dence, in our series of the mammillary region (77). In the embryo of

ten somites (Plate XXXIX, Fig. 2) these fundamental relations are

still recognizable, although important changes have supervened. Coin-

cidently with the ventral deflection of the extremity of the neuraxis, the

tubercle of the floor (2) has assumed a vertical position. A considerable

degree of closure has been effected ventrally in the anterior neuropore,

so that the tubercle no longer constitutes its ventral lip. The mammil-

SOHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 341

lary recess (/7) is better defined, the mammillary eminence projects

laterad but scarcely as yet forms a prominence in the mid-ventral line.

As a consequence of closure ventrad in the neuropore and of the ventral

deflection of the optic vesicles, a prominent angle is formed immediately

below the tubercle of the floor, which now intervenes between the two

recesses, the mammillary above and the one just described, the infundibu-

lar (18), below. The optic sulcus meets the floor-plate in the infun-

dibular region, but a shallow prolongation can still be followed beside

the tubercle of the floor. In the embryo of twelve somites (Plate XL,

Fig. 1), shght changes have supervened. The floor as a whole is thinner,

which may be taken as an expression of the expansion of the cavity, and

the tubercle of the floor (2) is no longer a conspicuous thickening. The

infundibular region (78) has increased in size and its cavity is more

widely confluent with that of the optic vesicles. Coincidently the termi-

nal portions of the optic sulci undergo reduction and lose their intimate

relation to the tubercle of the floor. A very faint furrow may be fol-

lowed from the optic vesicle across the parieties just above the remnant

of the tubercle, while the main line of the optic suleus extends into the

infundibular region. The tubercle of the floor is now losing its de-

marcation from the parieties with the effacement of the primitive ventral

segment of the optic sulcus, and from this period appears as a transverse

ridge intervening between the mammillary and infundibular regions.

It is, therefore, evident that the mammillary region arises from the

cephalic extremity of the primitive floor-plate and that the infundibular

region is a derivative of the primitive optic vesicles.

Not only ventrally but also dorsally the periphery of the optic vesicle

undergoes a remodeling and important new conditions are established.

First, a prominence is formed immediately in front of the anterior

isthmian sulcus, the thalamencephalon, and subsequently the telenceph-

alon emerges in front of this. The two elevations are separated by a

slight depression, the first indication of the velum transversum, from the

stage of thirteen somites, the earliest period at which the telencephalon

is recognizable. Both of these structures appear in the lip of the anterior

heuropore prior to its closure in their respective regions, and are accom-

panied by a recession of the optic vesicle from the margin of the medul-

lary plate and, what is of major importance, an absolute diminution in

the size of the vesicle. This is well marked in the period of from ten

to sixteen somites when the thalamencephalon, telencephalon and infundi-

bular region are well defined and the optic vesicle reaches the margin of

the neuraxis at only a single point between the infundibular region and

telencephalon. From this period the ventral pole of the vesicle slowly

342 ANNALS NEW YORK ACADEMY OF: SCIENCES

recedes from the margin, and the telencephalon becomes continuous with

the infundibular region. ‘There has thus been formed from the periphery

of the vesicle a series of derivatives which constitute an ectoptic arcade

and in each case the process has been the same, a remodeling of the

primitive optic vesicle, so that its central region ultimately constitutes

the definitive vesicle, while its periphery becomes allotted to the anlages

of the other elements of the prosencephalon which are, therefore, ectoptic

in their arrangement and cannot be reduced to a linear series of neuro-

meres referred to the longitudinal axis of the neural tube. We have

now summarized the ontogeny of the forebrain as it appears in our series

of embryos of the cat. It is hardly necessary to add that we are not

offering these conclusions as an explanation of the phylogeny of the

mammalian brain.

MESENCEPHALON

Closure of the neural tube and its separation from the ectoderm are

accomplished first in the midbrain. As elsewhere, the resulting roof is

concave. The concavity is present in the whole length of the neuraxis

but its degree increases cephalad and is most conspicuous in the fore-

brain. In the mesencephalon it is marked and persists to the stage of

sixteen somites; it is associated with a sagittal ridge which depends into

the lumen entally. In section the ridge is often constricted at its base

of attachment and occasionally a fragment of it is found separate as a

small group of cells within the neural canal. In the embryo of eight

somites the mesencephalon (15) is closed in half of its extent and forms

the highest region of the neural tube (Plate XXVII, Fig. 3). At nine

somites the closure is complete, the midbrain has lengthened and its

height has markedly diminished (Plate XXXI, Fig. 2, 75). A com-

parison of these two embryos throws some light upon the nature of these

changes. The distance between the quintal anlage and Sessel’s pocket

is the same in both models, but the interval between the optic vesicle

and the quintal ganglion has markedly increased, the axis of the optic

vesicle has altered and the forebrain has come to project strongly ventrad

at right angles to the rest of the neuraxis. These facts taken in con-

junction with the diminished height of the midbrain cannot be ade-

quately interpreted on the principle of unequal growth alone. It must

be taken as the expression of a remodeling of the whole region, in par-

ticular a lengthening of the dorsal portion of the midbrain without cor-

responding increase of its ventral parts, in consequence of which the

optic vesicle has not only been displaced but rotated through 90° and

the neuraxis has been bent ventrad in the region of the forebrain. There

SCHULTE AND TILNEY, NEURAXIS IN' THE DOMESTIC CAT 343

are no signs of compression in the mesencephalon but the slight bulge

of the mammillary region is, perhaps, the result of flexure.

In embryos of ten to twelve somites (Plates XXXII and XXXIII),

the mesencephalon acquires a triangular profile, demarcated from the

hindbrain by a shallow constriction which gradually becomes pronounced

and has a vertical direction (the posterior isthmian sulcus 23). The

anterior isthmian sulcus (22) is horizontal and forms a sharp boundary

against the mammillary region but becomes shallow cephalad near the

pole of the optic vesicle. A slight transverse depression of the roof

separates the midbrain from the thalamencephalon (76). ‘The walls are

convex and entally show nothing which can be taken for the sulcus

limitans of His. Ventrad the isthmian sulci converge to the angle made

by the forebrain with the floor of the neuraxis.

In the thirteen and fourteen somite embryos (Plate XXXIV), the

mesencephalon is gradually bent ventrad and comes to form the most

cephalic point of the brain. This bend is associated with clear evidences

of compression in the floor of the hindbrain. In the sixteen-somite

embryo (Plate XXXV), the mesencephalon has been carried slightly

beyond the crown of the cephalic arch and conjointly with the prosen-

cephalon (19) makes a right angle with the hindbrain. The isthmian

sulci now converge at an acute angle and the midbrain reaches the ventral

margin only by its pointed extremity. Ati this stage, a nuchal bend is

well defined and the effects of compression upon the mesencephalon are

at a maximum. From this period to that of twenty-one somites, the

midbrain lengthens in its dorsal segment and chiefly in a cephalic direc-

tion, as is shown by the alteration in the angle at which the anterior

isthmian furrow meets the floor as well as by the increased flexure of

the forebrain (Plates XXXVI-XXXVIII). We have described the mid-

brain as a single segment without subdivision into neuromeres, for,

though we have searched for evidence of a constriction, we have been

able to find none in any of our embryos save that of ten somites, No.

476, and here with less certainty than could be wished. A faint con-

cavity was present between the isthmian furrows and inclined so that

its continuation would have bisected their angle and divided the mid-

brain into a slightly larger cephalic and smaller caudal portion. It was

confined to the dorsal portion of the neural plate without, however,

causing a depression in the roof. The brain in this embryo was some-

what spirally twisted to the right and the depression in question was

not quite symmetrical on the two sides. For this reason and because

in all our other embryos the midbrain attains its greatest width precisely

in the region where this exceptional furrow appears, we are inclined to

attribute its presence to the unusual twist of the head.

344. ANNALS NEW YORK ACADEMY OF SCIENCES

2HOMBENCEPHALON

The large ganglia of the quintus, acoustico-facialis and profundus,

which develop in the order named, are associated in their inception with

sulci. These, beginning near the neurosomatic junction, and at first

parallel to it, eventually turn ventrad pursuing an oblique course across

the medullary fold. Each furrow is thus gomposed of a cephalic seg-

ment, intimately concerned in the formation of the ganglia and a caudal

portion which, becoming broad and shallow, occasions a dilatation of

the neuraxis. As the tube closes three oblique segments are formed.

In the embryo of ten somites (Plate XXXII, Fig. 2), where we were

first able to recognize the profundus anlage distinctly, four segments

were present. The first (32) is triangular in form with base ventrad,

extending from the posterior-isthmian sulcus to the oblique furrow at

the summit of which is the profundus ganglion (3a). This element has

no ganglion associated with it developmentally but owes its demarcation

to the establishment of a caudal boundary of the midbrain in the poste-

rior isthmian sulcus. It is followed by three oblique ganglionic segments

which are the expression of the oblique caudal portions of the ganglionie

sulci in the interior of tube. Externally three oblique intersegmental

constrictions are present, so that the third ganglionic segment lacks a

caudal boundary and merges into the relief of the myelencephalon. The

ganglia are situated at the summits of these furrows and are accordingly

intersegmental in their points of attachment, as was first pointed out by

Miss Platt.?°

This configuration is retained to the stage of thirteen somites. In

these embryos, and very vaguely in the more advanced embryos of twelve

somites, the surface of the neural tube behind the ganglionic segments

becomes marked by alternating constrictions and dilatations. These, in

marked contrast to the ganglionic segments, are vertical in position and

correspond to the mesodermic somites which abut upon the neuraxis in

the intervals between the dilatations. These vertical segments are un-

doubtedly the myelomeres of McClure! and are widely different struct-

ures from the oblique ganglionic segments of more cephalic position.

Primitively the two series are separated by a considerable interval which

is not effaced until the stage of fourteen somites, the most cephalic

myelomeres being relatively late in appearance. heir retardation, we

believe, is due to the small size of the mesodermic somites in this region,

WJ. B. Puatr: “A Contribution to the Morphology of the Vertebrate Head based on a

Study of Acanthias Vulgaris.””. Jour. Morph., Vol. V. 1891.

uc, F. W. McCrure: “The Primitive Segmentation of the Vertebrate Brain.’ Zool.

Anz. Jabrg., Vol. XII. W889:

SCHULTE AND TILNEY, NEURAXIS IN THE DOMESTIC CAT 345

so that they are slower in producing an effect upon the modeling of the

neuraxis. There is besides some evidence in the cat that somites are

added at the cephalic end of the series, which also would serve to explain

the retardation of the corresponding myelomeres. We are assuming that

the segmentation of the neuraxis into myelomeres is ontogenetically

secondary to the segmentation of the mesoderm, a view which receives

support from the fact that the number of myelomeres always lags behind

that of the somites, as well as by the fact that where the somites are

small and possibly retarded in appearance developmentally as in the

region just considered, there also the myelomeres are late in appearing.

“It is possible, therefore, to recognize two principles of segmentation

in the deuterencephalon; the first incident to the formation of the

cranial ganglia, the second associated with the segmentation of the

mesoderm, for it is to be noted that the appearance of the ganglionic

segments long antedates the branchiomeric segmentation. When, there-

fore, the series of myelomeres becomes continuous with the ganglionic

segments the result is not a meristic series of equivalents but comprises

structures diverse in their genesis and heterogeneous in their products.

In the stage of fourteen somites, the boundary between these two

series is gradually effaced and important changes supervene in the gang-

lionic segments. The first and second of these become subdivided ven-

trally. This is initiated in the first segment at the stage of fourteen

somites, in the second segment at nineteen somites. The third main-

tains itself as a small dilatation immediately in front of the first somite.

These changes coincide with the formation of the pontine angle, the

surface of which is marked by five elevations corresponding to the third

ganglionic segment and the subdivisions of the first and second. In

addition a small prominence, corresponding to the first myelomere, is

situated immediately caudal to the last of these elements and is also

recognizable at twenty-one somites (Plates XX XVII and XXXVIII).

If we now add to our reckoning the pre-ganglionic segment abutting

upon the posterior isthmian sulcus, a total of seven elevations is reached

for the hindbrain, a number within the limits of the count given by

students of the region in mammals, variation in which might well depend

upon the age of the embryo studied.

It would seem, therefore, that these elevations correspond to the

neuromeres of authors. We have endeavored to show that they are

secondary and heterogeneous.

346

ANNALS NEW YORK ACADEMY OF SCIENCES

ANNOTATIONS OF LEADERS ON ALL PLATES

Optic sulcus or vesicle.

Tubercle of the floor.

Quintal suleus or ganglion.

. Profundus ganglion.

Acoustico-facial sulcus or ganglion. °

Medullary plate or medullary fold.

Primitive groove.

Somatic ectoderm.

Anterior neuropore or its vestige.

Quintal hiatus.

Acoustico-facial hiatus.

Other hiatus in line of closure.

First ganglionic segment.

. First ganglionic segment: its cephalic portion.

. First ganglionic segment; its caudal portion.

Second ganglionic segment.

. Second ganglionic segment; its cephalic portion.

. Second ganglionic segment: its caudal portion.

Third ganglionic segment.

Mesencephalon.

Thalamencephalon.

Mammillary region.

Infundibular region.

Telencephalon.

Ganglionic crest.

Rhomboid fossa.

Anterior isthmian sulcus.

Posterior isthmian sulcus.

First myelomere.

Velum transversum.

Excrescence associated with vestige of anterior neuropore.

Region of transition between somatic ectoderm and neuraxis.

Mesoderm.

Entoderm.

Preganglionic segment of deuterencephalon.

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