Distribution and origin of life in America

Front matter

by Pali ine it at

NH Weara ie

- i ee

Preface

Tuts volume is the outcome of the second series of ‘‘ Swiney Lectures” on Geology which I delivered at the Victoria and Albert Museum in London in 1908. The subject chosen for these lectures was the ‘‘ Geological History of the American Fauna.’ Instead of publishing the lectures, like the previous ones on the “ European Fauna,” with little alteration, I decided to amplify and rewrite them completely. In doing so I was enabled to bring out more clearly certain points in the geological history of the American animals which seemed to me of general interest.

It is always difficult to choose a suitable title for a work of this kind. The one I have selected is brief yet comprehensive. At the same time, it may be urged that the origin and distribution of Man might reasonably be expected from the title, whereas it has been omitted in the text. This omission is mainly due to the fact that the literature dealing with the subject, exclusive of Man, is very extensive, while the origin and distribution of human races in America is treated in quite a distinct set of periodicals and books.

An important feature of my researches is the elucidation of some of the problems connected with the cause and nature of the ‘‘Ice Age” or ‘‘ Glacial Epoch.” There is a considerable amount of faunistic evidence that both the Atlantic and the Pacific oceans were closed simultaneously in the north, resulting in a higher temperature of these oceans and a greater snowfall in the countries surrounding them in the north. Similarly, if the Glacial Epoch had been due to a closing of the Arctic Ocean, the higher temperature prevailing in the Arctic

V1 PREFACE area during early Tertiary times must have been caused by a more abundant supply of warm currents in the Arctic Ocean at that time. Consequently North America would probably have been more isolated in the north than it is now, for the currents must have had ample facilities for passing freely into the Arctic Ocean. Palaeontological evidence, however, points to an intimate union of North America and the Old World during the greater part of the Tertiary Era. There are thus a number of interesting problems, all of which are fully discussed in this volume, quite apart from many other important theories arising out of the subject of the origin and distribution of life in North America. In this connection the testimony of fossil animals, and that of the marine fauna, has been largely availed of. To a certain degree the distribution of plants has also been included.

I have endeavoured, as far as possible, to quote all the more noteworthy works and papers dealing with the subject under consideration. Nevertheless I am conscious of having possibly overlooked a few important contributions; and I only hope my colleagues will be good enough to draw my attention to any omissions that they may notice, so as to enable me to add them in case a second edition of this book should be called for. I can lay no claim to having made careful studies of the literature dealing with the Geology or Botany of the American continents. The works cited are those that I happened to be acquainted with, and no doubt many gaps might be filled by those more conversant with these sciences than I am.

I have hesitated for some time before actually illustrating my views as to the former changes of land and water. Some geologists consider it inadvisable to publish palaeogeographical maps founded on zoogeographical data, since such maps are very liable to revision according to the constantly advancing state of our knowledge. The latter are also apt to lead to a good deal of adverse criticism, for one map can only represent a single short phase of a long series of geological ages during which repeated changes of land and water probably took place. In spite of these objections I have ventured to construct a few of these ideal maps of ancient geography as a

PREFACE Vil general illustration of my views. I have felt that although I am open to criticism, my views will be more easily understood, and we shall eventually make more rapid progress in arriving at the correct conclusions as to the alterations in the configuration of the oceans and continents that actually occurred in the past than if such maps were altogether omitted.

The immense advance that has been made in the United States in the study of zoology has greatly facilitated my work. And everywhere in America I found willing helpers ready to impart information. My thanks are particularly due in this respect to Prof. H. F. Osborn, Dr. Matthew and Dr. Hornaday of New York, to Prof. Morse and Mr. John Ritchie of Boston, to Dr. Henry B. Bigelow and Mr. T. Barbour of Harvard University, to the late Dr. A. E. Brown and Mr. Witmer Stone of Philadelphia, to Dr. Dall, Dr. T. W. Vaughan, Dr. Stejneger and Miss Richardson of Washington, to the late Prof. Packard of Providence, to Dr. Ortmann of Pittsburg, to Dr. Van Denburgh of San Francisco and to Dr. Ruthven of Ann Arbor. Several of my European friends also aided me in many ways. Among them particularly the following members of the staff of the British Museum: Dr. Smith Woodward, who was good enough to look through the proofs and to draw my attention to several errors, Dr. Andrews, Dr. Boulenger, Mr. Regan, Mr. Pyeraft and Mr. B. B. Woodward. Prof. Hull, Dr. Bruce and Dr. Stapf kindly pointed out to me various valuable sources of information. My most grateful acknowledgment, moreover, is due to the guardians of the Great Libraries, without whose ready assistance I should never have succeeded in accomplishing this work. The most generous facilities for study were given me by my friends Mr. Lyster of the National Library of Ireland, Mr. Praeger of the Royal Ivish Academy Library and Dr. Foord of the Royal Dublin Society’s Library. I am indebted, too, for many services to Mr. Kappel, the Librarian of the Linnean Society, to Mr. Jones, Librarian of the Geological Society, Mr. Waterhouse of the Zoological Society of London, and Mr. Hinch of the National Library of

Treland. a Iam under a great obligation to Messrs. Meiklejohn & Son

Vili PREFACE for allowing me to reproduce two of their beautiful oroscopic maps, while the council of the Royal Irish Academy, Prof. Osborn, Dr. von Ihering, Dr. Ortmann, Mr. Thompson Seton, Dr. True and Dr. Hornaday were good enough to give me permission to copy maps illustrating their works.

I can scarcely hope that all the conclusions I have arrived at in this book will be readily accepted, but I trust to have succeeded in impressing those who have not made a serious study of the science of geographical distribution of animals with the profound importance of the subject as an aid to palaeogeographical researches.

Ke ES.

Chapter I

THE FAUNA OF GREENLAND PAGE Description of Greenland—The reindeer and its origin—The Arctic musk ox—The lemming and Arctic hare—On the ancient land connections between Greenland and the adjoining continents—On the cause of the Ice Age—The marine fauna of the North Atlantic cited as evidence in favour of a northern land connection—Did the fauna of Greenland survive the Ice Age in the country ?—The snails of Greenland quoted in support of this theory—On the supposed polar origin of life—General faunistic affinities of Greenland with other northern countries. 1-25

Chapter II The Fauna Of North-eastern North America

Description of the general features of Labrador and its fauna—The voles and jumping mice—On some northern frogs—The origin and distribution of the moose deer—The fauna of the White Mountains and its origin—Pre-Glacial relict colonies in the North-East—Supposed effect of the Ice Age on the fauna-— Were the animals driven south by the cold P—On mild interglacial phases of the Glacial Epoch—Foraminifera in the Glacial drift deposits—The relict fauna of the Great Lakes—The fishes of the Great Lakes and their origin—Distribution and geological history of the fresh-water mussel Margaritana—The past history of the Great Lakes—The fauna of Newfoundland 26-57

Chapter III The Animals Of The Canadian North-west

The Mackenzie basin and its fauna—The lemmings and gophers —On American ptarmigans—The past history of the bison and its gradual destruction—On the distribution and origin of the wapiti deer—The Canadian tree - porcupine—On the molluscan fauna of the north-west and its relationship. 58-73 x CONTENTS

Chapter IV The Fauna Of Alaska Page

On the general features of Alaska, its glaciers, volcanoes and flora— Conditions of Alaska during the Glacial Epoch—On the evidences derived from the fossil mammals as to the former climate of the country—Evidences of an Asiatic invasion of animals into Alaska—The faunistic affinities of Alaska—On the former presence of the mammoth in Alaska—The fresh-water fishes of Alaska—The distribution and origin of the butterflies belonging to the genus Parnassius—-On the mammals peculiar to Alaska— On the relationship of the marine mollusks of the northern Pacific in recent and past times—Hvidences of a former land bridge near Bering Strait . . ; ‘ ; : - 74-100

Chapter V The Rocky Mountains And Their Inhabitants

The region of the Great Salt Lake—Distribution and origin of the mountain sheep and Rocky Mountain goat—On the geological history of the American deer tribe—the prong-horn antelope and its origin—On the Rocky Mountain flora—Accidental distribution as applied to butterflies— Description of the American game preserves—The great Tertiary deposits and their contents . ‘ 3 : : : : . 101-122

Chapter VI The Animals Of The Eastern States

On the poverty of lizards in this region—The snakes of the eastern states and their affinities—The origin and distribution of the garter snakes—Rattlesnakes and their range—On American tortoises and turtles—The giant salamanders of America and Asia—On newts and their allies—The relationship of the Hastern plants—The pine-barren flora—The range of the star-nosed mole . : ‘ : : ; 7 : . 123-143

Chapter VII The Fauna Of The Continental Basin

Description of the prairie region and its inhabitants—On the extinetion of the horse in America and the geological history of the horse tribe—Prairie dogs and their distribution—On the origin and past history of the raccoon—On caves and their contents as illustrating the geological history of the fauna—The former

CONTENTS xi

PAGE presence of the reindeer south of its existing range—Evidences of a southern fauna in the north and of its gradual southward retreat—Helicina—Turkeys and the Florida parrot—On the dispersal of fresh-water mussels—Relicts of the past—Bony-pike and bow-fin—The blind fauna of America. F < . 144-166

Chapter VIII The South-eastern States And Bermuda

On the vegetation and general features of Florida—The geological history of Florida—On the reptiles and amphibians of the south-east—The south-east as a centre of dispersal—The terrestrial mollusks of Florida—On scorpions and dragon-flies—Alligators and crocodiles, their origin and past history—The fauna of Bermuda island—The geology and flora of Bermuda—The birds and their origin—Terrestrial isopods, spiders and the land nemertean worm Geonemertes—On the snails of Bermuda and their ancestors—The origin of the Bermudan fauna . 167-195

Chapter IX South-western North America And Its Fauna

On the so-called “Sonoran Region ”—The palaeogeography of California and the adjoining States—On the western insectivores—On horned toads and burrowing lizards—Discontinuous distribution of some western toads—The snails of California— The fauna of lower California and its Cape region—On the European element of the Californian fauna as illustrated by the mollusks, butterflies and ants—The crayfishes of the south-west and their origin—Various faunistic problems—On mammalian affinities—The American rabbits and their relations— The former Atlantic land connections between the New World and the Old, supported by the evidence derived from Tertiary mammals—Conclusions . : 2 : é ‘ . 196-232

Chapter X The Fauna Of Central America

The fishes of Central America and their origin—On the geology and palaeogeography of Central America—Importance of determining the age of Central America—Hvidence derived from a study of the marine faunas—On the faunistic affinities between North and South America—The flora of Central America— Monkeys and raccoons—On birds, tortoises and snakes—The

Xil CONTENTS

PAGE fresh-water crabs and their dispersal—The Huropean element in the fauna of Central America—On discontinuous distribution of animals as a proof of their antiquity . . . . 233-260

Chapter XI The West Indian Islands And Their Inhabitants

The geology of the Antilles—Palaeography as illustrated by the distribution of snails—Antiquity and dispersal of snails, their relationship and European affinities—On the theory of the ancient Atlantis—The problem of the supposed permanence of ocean basins—The marine mammals of the Antilles and their origin—Evidences in favour of a mid-Atlantic land bridge—

The terrestrial mammals of the West Indian islands—Hvidences of former changes of level in the Antillean area—The blind animals of Cuba—On the ancient Antillean continent . 261-294

Chapter XII The Fauna And Flora Of The Galapagos Islands

Darwin’s visit to the islands and his views on the origin of their animals and plants—On accidental dispersal—The birds, tortoises and snails of the Galapagos islands—Origin of the flora—Baur’s criticisms of Darwin’s views-—Eupborbia and its past history—Conclusions as to the origin of the Galapagos fauna—The geological history of the Pacific Ocean—On the supposed former Pacific continent—Mr. Guppy’s researches— Coral reefs and their history—A circum-Pacific land belt— Evidences of ancient lands westward of Central America—On faunistic affinities between the Atlantic and Pacific oceans— The Humboldt current . i : . : : - 295-385

Chapter XIII The Animals Of The North-western States Of South America

The geological history of South America—The faunal elements of the continent—Palaeontology—Course of development of the continent during the Tertiary Era—Peripatus and its distribution in South America—On the origin of Clausilia and its relations—The South American bear—On the tapirs and their origin—The dwarf deer of South America—On the supposed existence of former land connections—Derivation and history of the fossil elephants—The river Amazon P ¢ . 336-362

CONTENTS xiii

Chapter XIV The Fauna Of Eastern South America Pagr

South American monkeys, their distribution and geological history —Sloths—The birds of South America—On fossil mammals and Old World affinities—The theory of an ancient land connection between South America and Africa—Evidence derived from the distribution of reptiles, amphibians, fishes, mollusks and fresh-water crabs—Dr. von Thering’s researches—Fernando de Noronha and St. Helena-—The fauna of St. Helena and its antiquity—Tristan da Cunha . ‘ . , : . 863-394 e

Chapter XV Argentina And Chile

The fauna of Argentina—Prof. Ameghino’s discoveries of fossils and their importance—Fossil edentates and rodents—Faunistic affinities—The llama and its origin—Fossil elephants—Ancient land connections between South and North America—Fossil plants — Floral affinities The circum-Pacific land belt— Antarctic problems—On the Antarctic continent—Affinities of the faunas of Patagonia and New Zealand—On a Pacific continent—The marine fauna of Patagonia—The Falkland islands—Antarctic expeditions—The pendulation theory 395-435

FIG.

_

LIST OF ILLUSTRATIONS

Map of North America (reproduced from Meiklejohn’s oroscopic maps by permission of Messrs. Meiklejohn & Son)

. Map of the North Atlantic, showing the supposed conditions of land and water during later Pliocene times (reproduced by permission of the Council of the Royal Irish Academy)

. Map of North America, showing the distribution of the Moose

Deer (reproduced by permission of Mr. Thompson Seton)

. Map showing the outlines of the White Mountain Plateau and

Mount Washington, with an inset Map of North America indicating the geographical position of the White Mountains

. Map of North America showing the original distribution of the

Bison, the range of the same species after the completion of the Union Pacific Railroad and its present range ae by permission of Dr. Hornaday) . a .

. Map of North America, showing the original distribution of the

Wapiti deer, and its range in 1900 (reproduced by een of Mr. Thompson Seton) F , ‘ : .

. Map of the northern parts of the northern hemisphere, showing the supposed land connections and the extent of the sea in the early part of the Glacial Epoch

. Map of the World, ee the distribution of the newt

Spelerpes ‘. . : . .

. Map of North America, showing the distribution of the Star-nosed Mole (reproduced by permission of Dr. True)

Map of North America, showing the distribution of the Reindeer (reproduced with some modifications by aa of Mr. Thompson Seton) . . . . : es

Map of North and South cap aoe the distribution of the snail Helicina : P

Map of the World, showing the distribution of the aie of fishes Cichlidae (reproduced by permission of Mr. Tate Regan)

PAGE

Xvi

FIG.

LIST OF ILLUSTRATIONS

Map of the West Indian as a the ee of the principal islands

Map of North and South America, indicating sate the supposed conditions of land and water about the commencement of the Tertiary Era

Map of the World, showing the conditions of land and water in upper Cretaceous times according to Dr. Ortmann (reproduced with the author’s permission)

Map of North and South America, indicating roughly the supposed conditions of land and water about the middle of the Tertiary Era

Map of the World, showing the conditions of land and water during the Eocene Period, according to Dr. von Ihering (reproduced with the author’s permission)

Map of South America (reproduced from Meiklejohn’s oroscopic maps, by permission of Messrs. Meiklejohn & Son)

Map indicating the distribution of the snail Clausilia in the Mediterranean region, in Africa and America, with an inset figure of Clausilia (Nenia)

Map of the World, showing the conditions of land and water in lower Tertiary times, according to Dr. Ortmann (reproduced with the author’s permission)

Map of the World, showing the conditions of land and water in late Cretaceous and basal Eocene times, according to Professor Osborn (reproduced with the author’s permission)

W YORK ILADELPHIA TIMORE

=} Highland over 1000 Feet.

Upland under 1000 Feet.

Lowland under 600 Feet.

Fic. 1.—Map of North America. (Reproduced from Meiklejohn’s Oroscopic Map, by permission of Messrs. Meiklejohn & Son.)

[Lo face p.1.

Distribution and Origin of Life in America

Chapter I The Fauna Of Greenland

GREENLAND geographically belongs to arctic America rather than to Europe, and, as it no doubt formed part of the land bridge that once connected America and Europe, its past history contains chapters of the greatest interest. Scanty as the fauna and flora of Greenland are, they afford us many a clue as to former changes of land and water which that country has undergone. Their study enables us also to trace the origin of the animals and plants of the neighbouring portion of continental America, which is one of the objects of the present work.

Greenland is now too well known to need a long description. Yet few readers realise the vast size of this stern and uninviting country, which covers an area considerably larger than the whole of France and Germany together. Threequarters, at least, of this area being completely buried under an enormous glacier ice-sheet, or inland ice, only a comparatively narrow belt of partly barren rocky ground is left along the shore on which animal and plant life is possible. The broadest exposed strip of land on the west coast of Greenland is about a hundred miles wide. Here and there two kinds of willows and the dwarf birch together form scrubby low-growing woods, the stems rarely rising more than a few feet from the ground. Thickets of alder, white birch and dwarf juniper likewise occur, while in sheltered nooks the

LeA. B

Lapland rhododendron, many kinds of saxifrages, cinquefoil, crowfoot, a willow-herb, a lousewort, the narrow-leaved arnica and other flowering plants for a time infuse variety into the brownish-grey landscape, giving it quite a gay appearance with the many brightly-coloured blossoms. During a couple of weeks in the short summer the natives may even have the advantage of gathering crow-berries (Empetrum nigrum), which grow in great abundance almost everywhere, just as they do in boreal America and Europe. ‘The bilberry and cowberry are also noticeable, but they are less common and do not seem to be used by the natives, nor is the cloudberry, whose fruit rarely ripens. All these are well-known Ameri and_European plants. The most valuable vegetable, which is largely used for food, is a tall angelica. It sometimes attains a height of six feet in favourable localities.

During early Tertiary times many species of conifers and several of our common deciduous oaks, poplars, walnuts, maples, lindens, magnolias and beeches flourished in Greenland. Many of the same trees also lived in Iceland, Spitsbergen, Grinnell Land, boreal North America and the New Siberian islands, It is evident that the climate all round the Arctia Ocean must have been mild. Many causes have been assigned for the change from the former temperate climatic conditions to the arctic ones now prevailing in the same region. A less restricted circulation of warm ocean water into the circumpolar area might, as has been suggested, help to bring about such a state. Yet it would not alone be sufficient. Sun and light for a longer period than now obtains would seem to have been necessary to ripen the wood of the trees and bring the fruit to maturity. At any rate, all this luxuriant flora must have disappeared from these northern regions long before the Ice Age. It is quite possible, and I even think it probable, that many of our common arctic and alpine plants originated in these remote Tertiary times. I cannot adduce any direct geological evidence for such a belief, since few of these plants possess properties which would enable the remains of their leaves to be preserved in a fossil condition. The assumption is founded chiefly on their wide geographical distribution.

As I am dealing mainly with faunistic problems, the

REINDEER AND ITS ORIGIN 3 animals of Greenland have to be considered more in detail. It is especially the beasts or mammals that are of importance because their distribution and geological history are better known than those of the smaller animals. They also enable us to readily appreciate the more recent changes in the fauna, and the causes which have led to them.

The most noteworthy and best known of the Greenland mammals is the reindeer. The term reindeer (Rangifer tarandus) is employed for the sake of convenience in its wide sense. In America it has been the custom for many years past to distinguish under the names of “ barren-ground caribou,” and “woodland caribou” two strikingly different forms which occur on the continent, the term “ caribou” being probably derived from the Indian word “ maccaribo.” Not only have these two kinds of reindeer dissimilar habits, they also differ from one another in size, and in the structure of their skulls and antlers. More recently, smaller groups of reindeer have been discovered, showing distinctive characters in their antlers alone. Several of the nine forms thus recognised as American are founded upon comparatively slight differences. An illustrated account of these various American reindeer has been given by Mr. Madison Grant.*

Mr. Lydekker + holds that they and the Old World forms are all referable to one single species, of which he distinguishes six varieties. Whether these differences are to be regarded as specific or varietal is a matter of opinion, but, as the antlers of reindeer are so very variable, it has been suggested by Professor Camerano that the structure of the skull might be utilised to greater advantage in discriminating between the various varieties or species. In his researches on the Spitsbergen form, he argues that there are three species, viz., the reindeer of Spitsbergen (R. spitsbergensis), the one inhabiting Greenland, Norway, Lapland and part of Siberia (R. tarandus), and lastly the American reindeer (R. caribou). Among the last two species he distinguishes again between the reindeer possessing cylindrical (cylindricornis) and those having compressed (compressicornis) antlers.

It is worthy of note that the reindeer of Scandinavia and

* Grant, Madison, ‘‘ The Caribou.” + Lydekker, R., ‘‘ The Deer of all Lands,” p. 33. B 2

Greenland constitute a single variety, according to Professor Camerano,* while Mr. Lydekker separates the Scandinavian from the Greenland race. Following Professor Camerano’s example, Dr. Lénnberg + prefers the nasal bones of the skull, to the antlers for specific diagnosis. He unites the Greenland, Spitsbergen and Scandinavian forms with the American barren-ground reindeer in one group, characterised by their flat nasals. The Finland and Siberian reindeer he holds to be quite distinct races, particularly the former, which, with its elevated nasal bones and somewhat flattened antlers, approaches the American woodland caribou. Even Robert Brown { long ago commented on the likeness of the Greenland and European reindeer, remarking that some reindeer horns from Greenland could not be distinguished from European ones. Since Professors Camerano and Lénnberg, moreover, take both skull characters and antlers into consideration, we may assume that this view of the affinity of the Greenland to the north-west European race is likely to be the correct one.

An anonymous writer in ‘“ Natural Science,” (p. 358, 1899) gave it as his opinion that there are no grounds for deciding whether the Old or the New World was the original home of the reindeer. No doubt he meant to convey that we know nothing of the ancestry of the reindeer. I ventured,§ on the contrary, to put forward the theory that the reindeer had originated in the Polar area, beyond the confines of the European Continent, while Professor Schlosser || argued that it was evidently of American origin. Neither of these views is supported by positive geological evidence; nevertheless I cannot agree with the above critic that we possess no grounds for deciding the place of origin of the reindeer, as the results of Professor Camerano’s and Professor Lénnberg’s cranial researches seem to indicate the existence of a closer relationship between the west European and the Greenland and

* Camerano, L., ‘‘ Renne delle Isole Spitzberge,”’ p. 167.

} Lonnberg, Einar, “Taxonomic Notes about Reindeer,” p. 10.

t Brown, Robert, “ Mammals of Greenland,’ p. 382.

|| Schlosser, M.,‘‘ Beziehungen d. ausgestorben. Saugethier-faunen,” p- 617.

REINDEER AND ITS ORIGIN 5 arctic American varieties than between the west European and the Siberian reindeer. The assumption that the species originated in Greenland or arctic America and thence spread along old land connections east and west to Europe and Asia, is, therefore, not quite so unjustified as Dr. Stejneger * seems to think.

But we must not forget the possibility of the reindeer having originated in the Old World. Dr. Brownt argues that the barren-ground variety .spread to America from western Europe by way of a Spitsbergen-Greenland land connection, while the other traversed Siberia, and crossed to the New World by Bering Strait. In the more southern parts of its range in America, new varieties may have arisen, perhaps owing to changes in the natural surroundings. Long cylindrical antlers were no doubt a disadvantage to reindeer in wooded districts, hence the beam became reduced in length and increased in width in what is known in America as the “ woodland caribou.” Some of these varieties, or species as many American naturalists choose to call them, intergrade to such an extent as to be difficult to discriminate from one another. Thus Rangifer stonei is a form of barren-ground reindeer living in Alaska, while Rangifer osborni is a woodland form. Dr. Allen, who first described them, considers them as well-marked species, while Mr. Osgood,{ during his travels in Alaska, finds that the differences between the two are all relative, that they are excessively variable and rather intangible. The mountain caribou (Rangifer montanus), originally described by Mr. Thompson Seton, is considered by Dr. Allen § to be allied to the woodland form, but distinguished from it in colour, size and shape of antlers. Mr. Seton,|| who has published a most instructive map of the geographical distribution of the caribou in North America, which has furnished me with the materials for the map given in this work (Fig. 10), thinks that in future the

* Stejneger, L., “Scharff’s History of the European Fauna,” p. 112.

+ Brown, A. E., ‘“‘ North American Big Game,” p. 87.

§ Allen, J. A., ‘Mountain Caribou,” pp. 8 & 9.

|| Seton, E. Thompson, ‘‘ Northern Animals, I.,” p. 192.

ten species now recognised in America will be reduced to four well-marked species.

How long the caribou or reindeer has been in existence we do not know. Its remains have been discovered both in Europe and America in deposits believed to have been laid down during the Pleistocene Period, and as these occur far to the south of its present range, it has invariably been assumed that the species was compelled, owing to unfavourable climatic changes to abandon its more northerly habitat. When the climate became once more suitable to its requirements, the reindeer is supposed to have returned to its, original home. This idea suggests that the reindeer originated in pre-Glacial times, and this view is, in my opinion, supported by the evidence of its occurrence, conjointly with the hyaena, in Irish cave deposits.*

The whole subject of the influence of the Glacial Epoch on animals and plants will be dealt with later on, and need not be considered here. The fact of the occurrence of undoubted reindeer remains far to the south of its present range certainly requires an explanation, and this is more easily given in conjunction with other facts to be stated in this chapter. While the reindeer still lives in Europe no further south than the fifty-second degree of latitude, in America it is found no less than seven degrees further south. In former times it inhabited Oregon and Kentucky. In the east it came down to the neighbourhood of the present site of New York City, whereas in Europe it advanced as far as Mentone on the shores of the Mediterranean, and penetrated to the north of Spain, 7.e., to the latitudes of the thirty-eighth degree in America and of the forty-third degree in Europe.t+

The musk ox (Ovibos moschatus) is another even more arctic mammal than the reindeer. So called from the musky odour of its flesh, this species was believed to be more closely allied to the sheep than to the ox, which it resembles more in size. In its geographical distribution it differs strikingly from that of the reindeer in so far as it is now quite confined to Greenland and arctic North America. It no longer inhabits

* Scharff, R. F., ‘‘ European Animals,” p. 112. t Brauer, A., ‘‘ Die arktische Subregion.”

ARCTIC MUSK OX 7 the Old World. Yet in Europe it penetrated as far as England and France in Pleistocene times, having apparently reached these countries from an eastward direction. While the reindeer occurs even in southern Greenland, the musk ox frequents only the north and east of that country.