^ I *WBWWBP > dp %AHVHaiH^ *WNm& \mV& i tfS* THE INTERNATIONAL SCIENTIFIC SERIES VOL. LIV. THE MAMMALIA IN THEIR RELATION TO PRIMEVAL TIMES BY OSCAE SCHMIDT PROFESSOR IN THE UNIVERSITY OP STRASBUR& WITH r IFFY-ONE WOODCUTS SECOND EDITION LONDON KEGAN PAUL, TRENCH, TRUBNER & CO. LTD. PATERNOSTER HOUSE, CHARING CROSS ROAD 1894 (Tk rights of translation and of reproduction are reserved) 703 S3&JF .PREFACE. IN the Preface to ths Third Edition of my 'Doctrine of Descent and Darwinism,' which ap- peared in 1883, I quoted the opinion of a famous lawyer as to the worthlessness of science, not with the intention of refuting it, but gave it as an example of the incredible naiveti with which eminent representatives of certain pronounced religious tendencies confront the work and results of natural science. Not long afterwards I was asked by a well-known man whether my lectures on zoology, at the university, treated of Darwinism as well. What my answer was is known to all those who have taken any interest in the ' theory of descent.' To those who have an understanding of the subject, and of the aims of a scientific interpretation of the living world (which is, in B 5O43 550800 VI PREFACE fact, the only one possible interpretation), I offer the present work as a supplement. It will be found to contain proofs of the necessity, the truth, and the value of Darwinism as the foundation for the theory of descent, within a limited field, and is brought down to the most recent- times. Within these limits the work is complete in itself; for although the student of natural history may have become acquainted with interesting fragments of the actual science, still the subject has not before been presented in so comprehensive a manner, or in so convenient a form. Together with my special studies of the zoology of the lower animals, I have for many years past felt myself peculiarly attracted by the advance of our knowledge of the Mammalia in their general relation to palaeontology and anthropology. From year to year I have followed this advance with increased interest, and always with a view to the principal questions connected with the domain as a whole. Hence I venture to offer this work to our younger and rising scientists as, I trust, a suggestive introduction to that ' portion PREFACE vii of the animal kingdom which stands closest to anthropology. My materials have been drawn from original works, when and wherever they were within my reach ; hence I never give extracts from extracts. I take it for granted that my readers, if not already in some measure acquainted with the forms and mode of life of the Mammalia, have at hand some such work as Brehm's ' Thierleben,' or Martin's 'Illustrirte Naturgeschichte der Thiere.' Books such as these, which nowadays occupy a pro- minent place in popular literature, make us acquainted with facts ; but, with the exception of C. Vogt's and Specht's works on the Mammalia, they go no farther. Now, as the theory of descent has shown, light and interpretation are shed upon the Present by the Past ; and thus the history of the development of animals, the history of the earth and geography, are made to confirm one another. In undertaking to give an introduction to illustrate this, I must observe that it will be possible only by overcoming a variety of difficul- ties, by entering upon various apparently trifling viii PREFACE details for instance, the construction of the teeth ; and these must not be regarded in themselves as merely amusing or entertaining, for, when brought into connection, these details often open up the most surprising and most wonderful prospects. By these enquiries we do not indeed arrive at the final cause of things, or at what the philosophers call the Thing Itself, but from an insight into the connection of the facts we obtain a higher arrangement for those facts. They demand an ever deeper penetration, and transport us into that creative state of enthusiasm which, by being the imaginative faculty of thinking-man, raises us above those who remain standing amid their own surroundings either in a state of blank amazement or of dull enjoyment. I am only following the usual custom by men- tioning, in conclusion, the assistance I have re- ceived from my daughter Johanna, to whose experienced hand I owe a series of original draw- ings, from which my illustrations have beem made. OSCAR SCHMIDT. STKASBUEG : September, 1884. CONTENTS. PEEFACE v I. GENERAL INTRODUCTION. 1. THE POSITION OF MAMMALS IN THE ANIMAL KINGDOM. . 1 2. PHENOMENA OF CONVERGENCE 14 3. THE DISTINCTIVE CHARACTERISTICS OF MAMMALS . . . 30 4. THE EXTENSION OP PAL^EONTOLOGICAL SCIENCE SINCE CUVIER 45 5. THE STRATA. OF THE TERTIARY FORMATION . . . . 77 II. SPECIAL COMPARISON OF THE LIVING MAMMALS AND THEIR ANCESTORS. 1. THE MONOTREMA, CLOACAL OR FORKED ANIMALS . . 86 2. THE MARSUPIALS y- / ^^ > 1 B 'I 2 2ZT /F F i m t ^ 1 9* ^ S) AP I W & s f v ^. ^ -^r: 1 FIG. 24. A. Left fore-foot of the Red Deer. B. Left fore-foot of the common Roe. c. Cannon-bone ; m, metacarpals ; p, upper phalange. C. Second row of tarsal and metatarsal bones of the Gelocus. After Kowalewsky. examples of this we may take the red deer and the common roe (Fig. 24). The rudimentary toes in both cases consist of three phalanges. In the red THE CERVIDE, OR DEER. 163 deer the first of these is smaller than the other two, whereas in the roe the first one is of the pro- portionate size. Now this arises from the fact that the rudimentary digits of the deer have become entirely detached from the metacarpals, and that only the rudimentary upper end of it remains (A, m). The roe still possesses the lower portion of this bone (B, m) and, moreover, in connection with the first phalange. The red deer is a ' plesio- metacarpal ' cervide, the common roe a ' tele-meta- carpal ' cervide. All the thirty-nine known species of Cervidae, confined to the Old World, are con- stituted like the deer with the exception of the two species of roe and the hornless Hydropotes in China, with which we have only recently become more intimately acquainted. These three latter species, however, as regards the construction of foot, are allied to the American deer. Of the twenty American species with tele-metacarpals, one, however, the Wapiti (Cervus canadensis), is not related to the others, but to the Europe-Asiatic group. From the formation of the foot, therefore, we find an almost perfect means for distinguishing the species. And this leads to the very natural supposi- tion that the American deer developed in the New 164 THE MAMMALIA. World, and the Europe- Asiatic species in the Old. It is only the ancestors of the Eoe and the Hydro- potes that must not be looked for in the Old World ; they are scattered members of the group from the other side of the ocean, like the Canadian species which, in the days when the two continents were connected by land, separated entirely from their Europe-Asiatic cousins. It is found in the Qua- ternary strata of Europe, e.g. in those of Louverne, near Le Mans, where it lived as a separate family by the side of the red deer, but soon afterwards, for some unknown causes, vanished from this locality and reappeared in the New World. The reduction of the side toes and the dis- appearance of the one or the other ends of the metacarpals took place after the still four-toed and geologically older stag-shaped animals had acquired antlers. This may have been the course taken by their development, unless we are to assume that the antlers appeared in different localities as a parallel formation, yet not till after the separation of the older hornless Euminants, which likewise showed a reduction of the limbs spoken of above. The latter case is very probable, and must be drawn into the circle of combinations, for in Gelocus we have become acquainted with a very ancient THE CERVID^E, OK DEER. 165 Ruminant of this kind, out of which both plesio- metacarpals as well as tele-metacarpals forms might have developed. Gelocus is an adaptive species of Ruminant from the Eocene. The skull as yet scarcely shows the character of the ruminant, but the molars are already reduced to J- , whereas other genera of the same age show *. The two principal metatarsals (Fig. 24, c, in, iv) have coalesced along almost their entire length ; the metatarsals of the side toes have, however, disappeared in the centre (Fig. 24, n, v), and only the lower and upper ends remain (in). Animals of this kind might have descendants with feet of the Deer species, another with feet like the Roe. At all events, deer and roe, both of these well-known denizens of our forests, have been strangers to one another from very remote times, strangers as complete as the Canadian stag (the Wapiti) is to all the other American Cervidae. An intermediate position between them is occu- pied by the Elk and Reindeer. Both are circumpolar species, and both, as regards construction of the foot as tele-metacarpal species are allied to the deer of the New World, the reindeer, moreover, by the form of the nasal cavity. Our material is at present too fragmentary to enable us clearly to 166 THE MAMMALIA, survey both sides. But all of these observations, which we owe principally to Sir Victor Brooke, 1 confirm Biitimeyer's remark that the form and development of the antlers can only very cautiously be made use of as a means for a strict classification of the Cervidse. Even though animals with antlers are met with as early as the Miocene, still the more complete development of true Deer belongs to very recent periods, and this explains their geographical dis- tribution in the main. In addition to the circum- polar reindeer and elk, Biitimeyer, agreeing with Brooke, reckons twenty species to America and thirty-nine to the Old World, many of which are certainly doubtful. An exchange between East and West seems evident, and yet, as we have seen, it was extremely limited. The remarkable want of deer in Africa beyond the desert, would have to be explained, with Wallace, by the fact that there must have existed obstacles almost insurmountable to the animals when they first began to distribute ; on the other hand, antelopes and even giraffes had either already passed the open road south- wards, or, owing to their organisation, had gra- 1 Brooke, ' On the Classification of the Cervidse,' Proc. Zool. Sac. 1S7& THE CERVID^, OR DEER. 167 dually overcome the difficulties presented by the desert. Zoologists have always classed the Musk Deer and the Dwarf Musk Deer (Tragulidte) with the true stags, although they are hornless animals. In doing this they have allowed themselves to be led by the general impression that the possession of antlers is not determinative of the relationship ; this had already been affirmed by Alphonse Milne- Edwards in 1864, and has been proved by their connection to the fossil forms that have now been brought to light. From these annexed groups the Hycemoschus aquaticus, which lives on the west coast of Africa, is of great importance as the con- necting link between the present and the remote past. Our Figure 25, A, gives the left fore-foot of this animal. Hyamoschus is also a decided two- hoofed animal, although the two middle metacarpals (in, rv) are entirely separate, and although the two outer metacarpals (n, v) are perfectly com- plete and the two lateral toes are developed and connected. Hycemoschm thus proves itself an adaptive form, inasmuch as the two toes that are no longer of use have ceded their right to the tarsals, to the principal toes, and thus increased the strength of the latter. The skeleton of the fore- 168 THE MAMMALIA. foot of the llyamosclius appears a slight modifi- cation of that of the Miocene Hyopotamus (Fig. A. Left fore-foot of Hyaemoschus aquaticus. . Same foot of Hyopotamus. After Kowalewsky. THE CERVID^E, OR DEER. 169 25, B). There both outer toes are still somewhat longer and stronger. Trapezoid and os magnum have not yet coalesced ; the metacarpals n and v are still connected with the carpals. Upon the whole, however, the differences between the living and the Miocene representatives of the pair-hoofed group are so slight that Hyamoschus may be called a surviving form of primary ruminant. The hind limbs of the Hyamosclius are more changed than the front limbs, owing to the two principal metatarsals having almost completely coalesced. A greater reduction of the hind limbs is often met with: for instance, the peccary has only one rudimentary toe on its back foot, whereas there are two on the fore-foot. This difference in the construction of the front and back limbs is, we think, to be explained by the greater amount of work which the hind legs have to accomplish ; for, as was said above, we look upon a reduction of this kind as an advance in the power of the adaptation. But, while we are naturally led back from our present Deer and Tragulidae to those early four- toed Hyopotamidse, we do not in any way mean to affirm that up to the Middle Tertiary all animals of the Ruminant group without horns or antlers possessed the full number of four toes. On the 170 THE MAMMALIA. contrary, it is found that the Anoplotherium from the Eocene of the Paris limestone, which has left no descendants, shows scarcely any traces of the second and fifth toes ; and by the side of the Hyopotamus, with four-toed feet, there existed the distinctly two-toed Gelocus, 1 whose extremities are almost as much reduced as the Deer ; and the same is the case with Diplopus. It would be rash to attempt to determine, among all these varied forms, which was the actual and definite primary form for the Deer or any other living group of the Rumi- nants ; still, any attempt to explain the striking relation between the past and present forms, other- wise than by means of the theory of descent and in accordance with Darwin's principle, cannot be expected from us. The share which homoeogenetic approximation may have taken in this connection has already been discussed. The same result is obtained by the condition of the teeth; and, as in the case of the limbs, the teeth must not be examined in the Deer by them- selves, the whole group of Ruminants must, first of all, be compared with the fossil forms. Among our living Hoofed animals the Giraffe 1 Filhol, 'Mammiteres fossiles de Eonzon, 1882,' Gelocus, Ancodus, and others ; their Relation to Hyopotamus. THE CERVID^E, OR DEER. 171 occupies a perfectly isolated position. Apart from its strange shape the result of a lengthening of the vertebrae of the neck and of the different lengths of its fore and hind limbs, descriptive zoology has very rightly laid stress upon the frontal deco- rations which adorn both sexes, and which have been said to be neither horns nor antlers. The two horn-like unbranched protuberances are covered with a hairy skin which never dries up as in the case of the deer, and hence they do not fall off periodically. These skin-covered bony protuber- ances cannot, however, be compared to the bony protuberances of the Oxen, as might be supposed, that is, to the processes of the frontal bone covered by the horn sheath. On the contrary, like the antlers proper, they begin as ossifications of the skin, and grow precisely in the same manner as antlers, but never become perfectly attached to the frontal bone. In order briefly to distinguish the character of the formations it may be said that Hollow-horned animals have frontal processes without antlers, The Deer processes with antlers, The Giraffes antlers without processes. Hence Butimeyer calls the giraffes ' a most fantastic form of deer.' 172 THE MAMMALIA. Like the lions and gazelles, the giraffes of Africa are probably immigrants from the South of Europe. Among the Mammalia buried at Pikermi is a species, Camelopardalis attica, almost the same size as the African variety. Unfortunately its skull is not known. The disproportion between the hind and fore limbs seems to have been even greater in the fossil species. Further traces lead us to the Siwalik hills in India. Numerous re- mains have enabled Gaudry to restore the com- plete skeleton of a genus closely allied to the giraffe the Hdladotherium which lived in herds in Miocene Aitica, and owing to their great size must have been characteristic figures in the land- scape of the primeval world. It was customary to class with the above the colossal Indian Sivatherium, which possessed a pair of simple horns in front, and a second branched pair. And yet our conjectures with regard to its affinity with the Giraffe are uncertain, and Eiiti- meyer thinks that the Sivatkerium points as much to the Antelopes, as the Giraffes to the Deer. Our knowledge of two other Indian species, the Brama- therium and Hydaspitherium, is as yefc so fragmen- tary that it is wiser not to make any conjecture as to their relationship. THE ANTELOPES AND OXEN. 173 The Giraffes stand close to the Deer, not because they have branched off from the deer, but because the unknown ancestors on both sides showed a disposition to certain reductions and convergences of a similar kind. 6. CAVICOENIA, HOLLOW HORNED ANIMALS. ANTELOPES AND OXEN. The horned Ruminants, which are grouped round the Chamois, Sheep, and Oxen and hence furnished with horn-cores rising from the frontal bones, and a horn sheath would appear to any- one to form a natural group. And even those who have not studied the subject would undertake to distinguish a Gazelle, as the representative of the Antelopes, from an Ox. The gracefulness of its whole appearance, more particularly of the horns, the smallness of the head, the slender shape of the legs, sharply distinguish the Antelopes from the Oxen, whose horns stand at the outermost point of the brow, whose skull is unwieldy in form, and whose legs (in keeping with the rest of the skeleton) are anything but graceful. However, when we examine the different families in any good collection, we shall find that by the side of the prevailing type of the slim antelope, there are various kinds of cow-shaped forms, with head and limbs in no way 174 THE MAMMALIA. resembling the Gazelles, yet almost all with horns strikingly different from those of Oxen. Finally, the gnu completely breaks down any systematic boundary, for by the form of its hindquarters and tail it resembles the horse. And into this group sheep and goat have to be brought. We can, it is true, distinguish them among one another by the characteristic traits of the family ; for instance, by the peculiar form of the skull. The ram, owing to the form and solidity of the nasal, lachrymal, and frontal bones, is able to give and to receive those tremendous blows of forehead against fore- head which would break the skull of the male goat. But there are sheep with goat-like horns ; and an animal that is clearly a sheep from the form of its skull has up to within recent times been called the musk ox. These resemblances it may positively be as- serted do not proceed from recent derivation or crossings, but must be traced back except in the case of the closely allied Sheep and Goats to con- vergences. Moreover, the Antelopes the most varied group of the living Euminants have not been so carefully studied in connection with their nearest fossil relatives as the Oxen. 1 1 Eiitimeyer's valuable investigations of this group may here be mentioned. THE ANTELOPES AND OXEN. 175 The distinguishing feature in the skull of the ox is most strongly developed in our domestic FIG. 26. Skull of a Short-horned Bull. /.Frontal bone ; n, nasal bone ; o, upper jawbone ; z, mid jawbone. 176 THE MAMMALIA. animal belonging to the genus Bos (Fig. 26). Here the parietals are pushed completely back from the top, or all but a small portion, to the abrupt incline at the back of the head. From a front view, or looked at from above, they cannot be seen at all. On the other hand, the frontal bones (Fig. 26) form great plate- shaped cover- FIG. 27. Skull of the Gazelle (Antelope arabica). *, Parietal ; /, frontal bone ; z, mid jawbone. ings to the forehead, and the bony processes rise upon their outer edge. As compared with the skull of an antelope (Fig. 27), the skull of our domestic ox has reached the extreme of a formation which is still repeated pretty perfectly in the individual development of the calf to the cow. It consists in this : that in the calf the skull is still THE ANTELOPES AND OXEN. 177 rounded, the frontal part is not, as yet, elongated, and the crown portion still forms actually a part of the upper covering of the skull. Only upon the appearances of the horn-cores and the lengthening of the frontal bones do we find the first indication of the abrupt rising up of the main back wall. The calf is therefore still antelope-shaped as regards the formation of its skull, as is shown in Fig. 27, where the whole length of the parietal bones are still to be seen from above, and the horn- cores do not occupy the backmost or outermost corner of the frontal bones. Sheep and goats also keep within the boundary of this type of the Ante- lope family. Calf and cow, therefore, again corro- borate the most important proposition of our doc- trine of descent : that the individual development is an abridged repetition of the historical develop- ment of the species. On the accompanying table of Eiitimeyer's we have the sub-families of the Oxen classed according to the form of their skulls. It b ^ins with the buffaloes, which, as regards skull and the position of their horns, have deviated v ast from the Ante- lopes, and closes with the domestic ox, which has differentiated the most. We gather from this table which contains the quintessence of all the 178 THE MAMMALIA. TABULAR VIEW OF THE FOSSIL AND LIVING Ox EM (AFTER RUTIMEYER). Miocene ? Pliocene Pleistocene Living I. Bubalina Bubalus caffer Buffelus antiquus sivalensis bvachyceros indicus (domestic ox) sondaicus Pallasii Probubalus triquetri- rostris Amphibos acutiformis antelopinus (Anoa) celebensis II. Portacina Leptobos Falconeri Strozzi Frazeri III Bibovina Bibos etruscus Palffio- Gaurus Gaurus ? Gavseus sondaicus indicus IV. Bisontia grunniens (Yak) Bison sivalensis priscus europfeus latifrons americanus V. Taurina Bos planifrons namadicus primigenius taurus f. primi- genius f. trochocerus investigations made on the subject that our know- ledge is still meagre enough, inasmuch as at the Pliocene stage where true oxen are first met with we already find the transition from the buffalo to the ox in its narrower sense. The different THE ANTELOPES AND OXEN. 179 European oxen l have all, perhaps, to be traced back to the Diluvial Urus, or wild bull (Bos primigenius), and the races which branched off as early as the*. Diluvial period. 2 If, in accordance with the above standpoints, the skull of the domestic ox, of the bison, the yak, and the Indo-European buffalo, be com- pared with that of the antelope, it will be found that the resemblance to the antelope will become more and more apparent. Thus the bison (Fig. 28) is still so like the ox that, as we shall see, it might be doubted whether one of our races, the Dux cattle of Eastern Tyrol, is to be traced back to the wild bull or to the bison. On the other hand, the Anoa of Celebes, which Riitimeyer calls the Probti- balus celebensis, is indeed still an ox in all its out- ward characteristics (' the dwarf of the ox family '), but is a complete antelope as regards the position of its frontal and parietal bones (Fig. 29). This agreement in the outward parts must scientifically 1 The three most important races of oxen which have to be traced back to Bos primigenius are : Brachyceros race . . . Appenzell cattle Primigenius race . . . Holland cattle Frontosus race .... Bern cattle 2 A good survey of the investigations and opinions as to the origin of the domestic ox is given in Friihling's Landwirth- schaftlicher Zeitung, Feb. 1878; Pagenstecher, Studien zuin Ur sprung des Rimles. v 2 180 THE MAMMALIA. be regarded as a convergence, in the skull as an homology. Fia. 28. Skull of the Bison americanus. After Wilckens. It has been stated that the separation of the THE ANTELOPES AND OXEN. 181 antlered from the horned animals is met with first in the Miocene, or, in other words, that deer and antelopes are difficult to distinguish before that period. Later we have the branching off of the oxen, but we cannot closely define the point of FIG. 29. Skull of the Anoa. After Eiitimeyer. s, Parietals ; /, frontal bone. attachment. In the Lower Miocene and Eocene, the Euminants are represented by distinctly pair- hoofed and crescentic-toothed animals, which, although absolutely without horn-cores on the frontal bones, are distinguished by a very full dentition without gaps, some being without the 182 THE MAMMALIA. prominent canine teeth which serve the others as weapons. An early Selenodont (crescentic-toothed) animal of this kind for the primeval pair-hoofed group one which, like the Hyopotamus, does not belong distinctly to any special type is the genus Cainotherium, an animal of the most graceful shape ; we have probably a correct picture of its appear- ance in the living dwarf musk-animals (Fig. 30). That Cainotherium and its relatives, e.g. Xipho- don, Xiphodontherium, were Euminants, cannot be doubted from the position and nature of the tranverse ridges of their molars, also from the character of the joints of the jaw upon which depends the peculiar action of the grinders. The O -J A Q dental formulae is i _ c _ p -, m ~ ., and in most o 1 4 a specimens they stand in closed rows in both jaws. Now our present hollow-horned animals have no incisors in the upper jaw, and no canines either in the upper or lower jaw, and, moreover, they occur in the upper jaw only in some species of deer. The diminution of the teeth a very general pheno- menon must, therefore, have taken place gradu- ally in the course of ages. How and when this occurred, Filhol ' has very clearly pointed out with 1 Compare p. 64, note 2. THE ANTELOPES AND OXEN. 183 respect to the above-mentioned animals. The Cainotheria, to judge from the quantities of their remains, must have lived in herds after the manner of the Antelopes ; hence hundreds of skulls and thousands of lower jaws could be compared. Further, an extraordinary variability was found Fro. 30. Skull of Cainothcrium metopias. Nat. size (after Filhol). in the canine tooth (Fig. 80, c), and in the front premolars. The normal row of teeth, i.e. the teeth inherited from early times, begins to show gaps ; a small gap occurs between the canine and the first premolar ; the latter then moves towards the canine ; frequently the second premolar follows ; both thus obviously become useless, and the next 184 THE MAMMALIA. stage is their total disappearance. Further, we then see indications of the brow weapons, in correlation with the loss of the canines. Filhol here reminds us of the proposition expressed even by Aristotle, and formulated again at the beginning of this century by Etienne Geoffrey St. Hilaire with regard to the balancing of the organs (balancement des organes). With the loss of the front premolars, the permanent molars become more regularly developed, and it is thus that the now typical ruminant jaw has been farther and farther developed ; the ancient form owing to complete rows of teeth and the more marked canines still, in some measure, resembled the jaw of the Omnivora and the Bunodonts (animal with tuberculate teeth). From Filhol's observations we find that this process of the gradual formation and the fixing of the gap in the dentition of the Kuminants has repeated itself that, at first, individual modifica- tions became established by inheritance, and led to the formation of races. And although we cannot, in every instance, trace the given advan- tages connected with the modifications, and that led to the selection, still, as was shown above, we have some idea, as well as some explanation, of THE ANTELOPES AND OXEN. 185 the advantages, and they account for the gradual disappearance of the primary groups and for the origin of new species. In America we find the same circumstances. Antelopes and oxen have, it is true, decreased in a remarkable manner among the present American fauna, but the abundance of the fossil forms is so great that we can scarcely find fault with the patriotism of the American naturalists, when we find them, in this case also, claiming their country to have been the cradle of this group of Hoofed animals. Of purely American types we will name only the very numerous family of the Oreodonta, which combines traits of the pig-shaped pair- hoofed, or thick-skinned animals, i.e. the large canines as weapons, and molars of the ruminant type. They were so numerous in the Middle Eocene that one stratum has been called after them, and, together with this force of numbers, they show that tendency to differentiate into races and species which seems to be characteristic of pri- mary forms. Although America was rich in the still indefinite precursors of our present Euminants, it has re- mained absolutely unproductive as regards Oxen. For even the Diluvial ancestor of the North Ameri- 186 THE MAMMALIA. can bison might be disputed as belonging to America. This naturally touches upon extremely important points in anthropology and the history of civilisa- tion, particularly in connection with the other cir- cumstance that the line of horses was broken off precisely at the point where the American Man first appeared on the scene ; and moreover when he was still in so rude and helpless a state that he could not have brought either one or the other of his fellow-workers with him from his Asiatic home, to aid him in his further advance in civilisation. Hence the same phenomenon, as was shown above to have occurred in Australia, has been repeated here, even though in a less striking manner. Even at the beginning of our century, buffaloes (Bison americanus) crossing the prairies were to be counted by hundreds of thousands. Nothing points to the fact that the American aborigines ever made any attempt to tame these wild creatures. It would seem rather that throughout the whole of North America the Indian was, in a manner, chained to the buffalo, and that from year to year he had to pass from one pasture to another with the animal. Hence it was impossible that the higher civilisation of a settled life could take the place of a huntsman's career. Only those tribes which wandered from THE ANTELOPES AND OXEN. 187 the north southwards, to central and to one part of South America, could attain any comparatively high development of civil life ; and this was owing to the more favourable climatic circumstances, and to various species of llamas having been made use of as domestic animals. The introduction of oxen and of horses from Europe was the beginning of the end of the Ameri- can bison. The bison has found its biographer in Professor Allen, 1 who has clearly pointed out its relation to the Diluvial races ; and as regards this relation Allen arrives at a somewhat different con- clusion to what Rutimeyer* does. The earliest form is the gigantic Bison latifrons from the Diluvial strata of North America, where also are found the remains of mastodon, megalonyx, mylodon, and others. It produced species (races?) not very different from one another, the Bison antiquus of the New World, and the B. priscus of the Old World. The latter is the progenitor of the Europe-Asiatic urus or wild bull ; the Bison antiquus, which lived contem- poraneously with the Elephas primigenius, is the progenitor of the Bison americanus. It is very probable, as already remarked, that 1 Allen, The American Bison. Cambridge, Mass., 1876, 2 See above, p. 178. 188 THE MAMMALIA. the original inhabitants of America did not make any attempts to tame the buffalo. At all events, they did not succeed in doing so. Very different have been the results of the attempts of the Euro- pean immigrants, who have repeatedly been engaged in this task since the middle of last century. They have succeeded pretty easily in obtaining a cross between the wild and the domestic animal, by allowing the captured young ones to grow up in the herd ; and it seems certain that this will produce a strong cross-breed. A Mr. Thompson, who, ac- cording to Allen, had watched the attempts at domestication of the unmixed species during fifty years, has expressed his conviction that the animal is capable of being employed for work as well as for yielding milk, while the earlier attempts at cross- breeding were made principally with a view to the horns and skins of the animals. Under these circumstances, it seems natural that the question should arise as to whether one or the other race of the European ox must not be traced back to the bison. All those who have carefully studied the question declare the bison to be unfit for domestication, and have referred all the different races of the domestic ox with the exception of the yak to the genus Bos distinguished by the THE ODD-HOOFED ANIMALS. 189 characteristic formation of the forehead. Wilckens alone 1 has drawn attention to the resemblance between the skull of the short-headed cattle of Eastern Tyrol (Dux) and that of the bison, and thinks that further investigations would furnish a complete proof for this derivation. Perissodactyla, or Odd-hoofed Animals. The Odd-hoofed animals are at present repre- sented by three groups: Tapir, Ehinoceros, and Horse, all of which are poor in species. The re- duction in the fore and hind- foot has advanced farthest in the horse ; the middle toe, owing to the complete disappearance of the others, has become the sole support for the weight of the body. There exist only the mere rudiments of the metatarsals of the second and fourth toe. The tapir comes first with four toes on the fore-foot, and three on the hind-foot; the rhinoceros has three toes on both the fore and the hind limbs, and both these groups have preserved very ancient characteristic features. But in spite of its transformation having advanced so far, no other mammal of the present 1 Wilckens, ' Ueber die Schadelknochen des Rindes aus den Pfahlbauten des Laibacher Moores, 1877 ' (Communications to the Anthropological Society of Vienna), 190 THE MAMMALIA. day can show as distinct or regular a pedigree as the horse. By means of the accompanying table we will endeavour to solve our problem. The con- nections are, upon the whole, so simple and clear that, although palaeontologists may differ in the explanation of the relationships, these differences refer merely to subordinate points. TABLE SHOWING THE CONNECTION BETWEEN THE ODD-HOOFED ANIMALS. Present Time Tapir Rhinoceros Horse Diluvium Elasmotherium Pliohippus ' f Hipparion Protohippus Tapir Rhinoceros Aceratherium Anchitherium Miohippns Miocene Mesohippus Palffiotherhim med. Orohippus Lophiodon f Palaeotherium Eohippus Eocene Palffiotheridte (four and three toed) I Anti-Eocene odd-hoofed animals 1 American line of horses. 1. TAPIE AND RHINOCEROS. Of Tapirs we have two or perhaps three species in South America, and one in India. Their favourite haunts are moist forests. Their dentition is very complete in spite of a considerable gap between the canines and molars. The dental for- THE TAPIR AND RHINOCEROS. 191 The incisors and canine teeth are, as usual, not of any special form or construction, whereas the cheek-teeth show a very peculiar type by the marked character of two transverse ridges, the tops of which, both inside and outside, become tolerably sharp tubercles (Fig. 32). The ridges of the upper teeth are situated on the front and in the middle Fio. 31. Skull of the Tapir (Tapirus americanus). n, Nasal bone ; t, bony wall separating the nasal cavities. of the crown ; they fit into the grooves of the lower molars, where the back ridge rises from the back wall of the tooth. The grinding movement peculiar to the Euminants can be accomplished by the tapirs only in a very slight measure ; on the other hand, their teeth are specially adapted for crushing vege- table substances, which can also be roughly cut by 192 THE MAMMALIA. the sharp ridges of the crowns of their teeth. Although the fore-foot of the tapir possesses four perfect toes, still, from an examination of the skeleton of the foot, it becomes evident at once that the second toe from the inner side, corresponding with the middle toe of the five-toed limb, is more strongly developed than the rest, and that it stands in that peculiar position which we have shown to a FIG. 32. Back Molar of the Lophiodon parisiensis, on the left from below. A, a, Front and back outer tubercle ; /, i, front and back inner tubercle. be the distinguishing feature in the Odd-hoofed animals. A five-toed genus with the middle toe in this position has, as we have seen, been preserved in the Coryphodon from the Eocene formation. Now, as the lowest known tapir-shaped animals possess at most four toes, the unknown primary forms must, of course, be looked for in the secon- dary divisions. The tapir, in addition to having lost the inner toe, has also lost the fifth toe ; this THE TAPIE AND RHINOCEROS. 193 is another instance of the law laid down on p. 169, that the hind extremities are more readily and more frequently reduced than the fore limbs. In the tapir we have an animal from the Early Tertiary period that has remained almost wholly unchanged, one of those species which have been called permanent, and which are more frequently met with in the lower animal world. They do not prove the invariability of the species, but prove only that under certain circumstances the stability of the species can be of an extremely long duration. In the Miocene the genus is represented by several good species. In the Middle Eocene, we have in its place the Lophiodon, which is characterised by a still greater simplicity of the ridges of the teeth, and, as regards appearance generally, may have been scarcely distinguishable from the tapir. The European Lophiodonts naturally, in the first place, lead over to the Indian caparisoned tapir. The American ancestral line of the tapirs is more com- plete. Two genera, Helaletes and Hyrachyns, closely related to Lophiodon, belong to the Eocene. They may be called tapiroid forms. At a somewhat later period appears LopJiiodon, one of the few genera we have in common. Still more tapiroid in form is the Miocene Tapiravus, which in the o 194 THE MAMMALIA. Post Tertiary is followed by the tapir itself. That the animal migrated to its present home in South America is probably certain. Now Eocene races existed in the Eastern as well as in the Western Hemisphere, whose origin and separation is in- deed unknown, but the form and character of the feet and teeth would require but small changes to produce the genus Tapir. Hence it is here again merely a matter of opinion (owing to the present state of our knowledge) whether, with Marsh, we consider it more likely that the original home of the tapirs is assigned to the New World, and that they are supposed to have migrated to Asia, or vice versa ; or again, if, with Carl Vogt, a parallel development is considered the more prob- able hypothesis. By the side of our present tapirs, and unmistak- ably allied to them in the formation of foot and dentition, stand the Rhinoceroses, which are dis- tributed over Southern Asia, with its large islands, and Africa. The head weapons are solid horny projections of the nasal bone, which rise into a flat hump within equalities of the bone substance. From this characteristic feature it can in most cases be determined whether the fossil animals of the Khinoceros species possessed horns. THE TAPIK AND EHINOCEROS. 195 Throughout the whole of the Diluvium and the Tertiary period up to the Palseotheriae and Lio- phodons, there existed rhinoceroses, or hornless animals closely related to them. Midway in the line stands the" hornless Aceratherium. Its connection with the Palseotheridae and the Tapiridae becomes at once apparent from an examination of the skull ; still, a diminution of the front and canine teeth has taken place. In fact, the whole family of the Khinoceridse, up to the present day, shows more variability of the incisors and canines than any other group. The dental formula of the Acerathe- 2 7 rium is . Also by possessing four toes on the fore-limbs it stood closest to its five-toed an- cestors. Aceratherium is followed upwards by the true rhinoceros with enlarged nasal bones capable of supporting heavy horns. In several of the Diluvial species above all, in Rhinoceros ticho- rhinus, 1 which ranged across Central Europe as far as the Asiatic Polar Ocean the otherwise gristly 1 A rhinoceros, with a bony partition between the nostrils, lived in Europe with the mammoth up to the period of Man, and its fossil remains, like those of its contemporary, helped our fore- fathers in their conception of giants and dragons. On the market place in Klagenfurt is a very old stone image of a dragon, the head of which has most unmistakably been modelled from the skull of lihinoccros tichorhimis. o 2 196 THE MAMMALIA. partition between the nostrils became a firm bony support for the horn, an ossification, which is not unfrequently met with in the tapir, as was shown on Fig. 31. America, too, had its family of Ehinoceroses, which seem to have branched off from the Middle Eocene Tapiridse, and comes forward distinctly in the Upper Miocene as Aceratherium. Forms similar to it are found in the Pliocene, but did not leave any descendants to the following period. The causes of its extinction in the New World are not clear. But the reason of the dying out of the Diluvial species in the Old World, or its withdrawal from the temperate zones to tropical regions, seems to be pretty obvious. For even though individual forms such as the rhinoceros with the bony par- tition between the nostrils were, like the mam- moth, able to endure a rougher climate, still they were not able to face the coming of the Glacial period. What prevented them withdrawing before it we certainly do not know ; still we may, at all events, look upon them as having been the victims of climatic changes. Others, which were able to avail themselves of the land bridges for with- drawing southwards, survived. An animal of the rhinoceros type, which was THE TAPIR AND RHINOCEEOS. 197 perhaps a contemporary of Man, and one of the most gigantic phenomena of the primeval world, is the Elasmotherium. It likewise possessed a bony partition between the nostrils, and was armed with an immense horn, as is proved by the rough and huge elevation on its forehead. Its skull is over three feet in length. The form of the molars, with elaborately folded plates of enamel, is another FIG. 33. Skull of the Elasmotherium. One-twelfth nat. size. After Brandt. peculiarity. This giant of the Diluvial period was also unable to preserve its existence. The few remains among which is an almost complete skull have scarcely been found anywhere except in the southern basin of the Volga. The size of the present animals of the Ehinoceros species, and of most of the primary species, will seem less striking if we take into consideration the 198 THE MAMMALIA. smaller species of bygone days, for instance, the Rhinoceros minutus. Before passing on to the most docile and important group of the Odd-hoofed animals, the horses, let us first turn our attention to a few of the American forms, which are distinguished partly by their size and partly by the, in most cases, very unusual form of their skull ; in the struggle for exist- ence these animals, however, neither changed nor left descendants which adapted themselves to cir- cumstances. Their existence reminds us of the Elasmotherium, inasmuch as they neither explain the present (hence in reality stand apart from our subject here), nor do they awaken in us other ideas for understanding the organic world ; but they bear witness to the incredible exuberance, we may almost say the capriciousness, of organic produc- tivity during the Late Tertiary and Diluvial periods while the animals were becoming extinct, and which periods were followed by our Present age, with a certain stability of the inorganic and organic worlds. In this stability of forms, moreover, we see one of the preliminary conditions of the morphological and social development of mankind. The lowest strata to the east of the Eocky Mountains contain the remains of the Brontotheridce, THE TAPIR AND EHINOCEROS. 199 gigantic animals, whose bodies exceeded that of the elephant in bulk, but they had shorter limbs with FIG. 34. Skull of Brontotherium ingens. One-tenth nat. size, n, Nasal bone ; t, mid jawbone ; m, upper jaw ; j, cheek bone ; /, frontal boae ; p, parietal bone ; c, condyle. The same looked at from above, with the brain given in outline. After Marsh. four toes on the front feet and three behind. The skull (Fig. 34), which is elongated after the manner 200 THE MAMMALIA. of the Khinoceros species, shows a pair of bony protuberances (the supports for mighty horns) on the upper jaw, in front of the eye-cavities, and prob- ably the nasal bones and the intermediate space between the horns permitted the addition of a proboscis. Both in the case of Brontotherium as well as in some members of the family of the gigantic Dinocerata, to be spoken of presently, the relative size of the brain to the skull is known from fossil impressions. According to these the size of the actual brain substance must have been extremely small (Fig. 34, B.). Its extent reminds one of the relative proportions of the reptile brain, and points to an incongruity which must certainly have had its effect upon the dying out of this and of similar species. It was in this manner that all the huge reptiles of the middle geological periods became extinct, especially as land animals. The few huge but small-brained reptiles of the present day, such as the crocodiles, clearly owe their existence to the fact that they have continued to live in water, also to their marked stability. A transition to life on land would lead to their extinction. From the circumstance that one of the more recent strata of Oregon contains the remains of a THE EQUID.E, OR HORSES. 201 perhaps kindred genus, the Chalicotherium which is discovered also in Western America, in China, India, Greece, Germany, and France Marsh con- cludes that the places where these remains were found were the stages by which, in this and other cases, the so-called ' Old World ' received its animal forms. 2. THE EQUID.&:, OR HORSES. On Fig. 35 we have a drawing, made by Owen in 1857, to explain to his audience the derivation of the one-hoofed animal from its three-hoofed ancestor, a drawing which has been made use of countless times since then by recent writers. The three-hoofed animal is the Palceotherium medius discovered by Cuvier ; in outward appearance the foot is precisely like that of the tapir, but possesses four toes on its fore-foot, and thus represents an earlier form. The Palseotheridae are essentially Eocene ; to judge from their teeth, they obtained their food like the tapirs, and (with a numerous kindred) inhabited the marshy forests which had originated with the upheaval of the weird depths of the Jura and Chalk oceans. They, too, had found their way to Southern America. It is, we know, perfectly use- less, at the present state of our geological know- ledge, to endeavour to determine by means of 202 THE MAMMALIA. which land-bridges this migration took place ; all that can be done meanwhile, is to trace the line of the descendants of the Palaeotheridse, which, it seems, soon came to an end in South America, but became very numerously and continuously de- FIG. 35. Palffiotherium. Hipparion. Horse (after Owen). f, First premolar ; m, first molar. veloped in North America ; and in tracing this line we must do so independently of those branches which run parallel with them in Europe and Asia. Palseotherium is a distinctly three-hoofed animal. Certainly the middle toe is somewhat larger than THE EQUIDjE, OR HORSES. 203 the two side toes, which, although shortened a little, and accordingly somewhat more perpen- dicular, yet fully touch the ground, and take their share. in the work as bearers of the weight of the body. Now in the genera which gradually arose in the course of time Palceoiherium, Anchi- therium, Hipparion, and Horse we can trace how the two side toes, n and iv, were more and more withdrawn from the ground, and became rudi- mentary, whereas the middle toe increased in size, stretched out, and finally became that of the Horse, the incomparable runner and fellow- worker of man. Owen looks upon this as a providential transforma- tion designed for the benefit of mankind ; we look upon it as an adaptation to the formation of the ground, to the incoming of plains, which originated during the Tertiary period. Thus in Anckitherium aurelianense (Fig. 36), which is still met with even in the Eocene, the tips of the outer toes are scarcely withdrawn from the ground, hence might still have been of use to the animal in walking through a less firm soil. The Hipparion also, from the Middle Tertiary, possesses the lateral toes (Fig. 35), but these are only rudiments of the original toes. They have become wholly useless, and in accordance with this inaction 204 THE MAMMALIA. the bones of the middle foot have also become shortened, and are on the way of becoming rudimentary. In Hipparion the adaptation of an animal once accustomed to marshy ground, to one which lived on firmer ground with extensive meadow lands has become completed ; we have, in fact, the transforma- tion from a slowly-moving into a swift animal. It ranged from Central Europe as far as Central Asia, and in both countries lived in enormous herds, as we learn from Gaudry's graphic picture of the Miocene uplands of Pikermi. The transition from Hip- parion to the Horse is a very natural one. The two side toes which are no longer of use to the organism, and yet had to be FIG. 36. Left hind-foot of the Anchitherium. One-half nat. size. After Kowalewsky. THE EQUIDJS, OR HORSES. 205 nourished have been eliminated as ballast. They are not yet quite cast off. The metatarsals, or so-called 'splint bones,' are still attached to the middle toe. The horse of the future will certainly have cast off these rudiments, even though it may take a few millions of years to accomplish this, owing to the extraordinary perseverance with which organisms drag about with them these useless in- heritances. The Hipparion has not even yet wholly disappeared from the scenes of life. Now and again horses have been met with, with more than one toe, which must not rashly be considered as a malformation ; it is simply a proof of that repetition of or reversion to the original form which in scientific language is called atavism. This kind of Hipparion-horse, which is looked upon by the common run of people as a curiosity and monstrosity, has, as Siebold 1 has shown, been repeatedly exhibited at horse-markets. The fol- lowing is a description of an animal of this kind given by Frank, Principal of the Veterinary College of Surgery at Munich : ' The so-called splint bones (the metacarpals and metatarsals of the second and fifth toes) are not reduced to the same extent. On the fore-foot the mediale (M c 2) is the least 1 Siebold, Hipparion auf Jahrmarkten. Miinchen, 1881. 206 THE MAMMALIA. reduced, on the hind- foot the lateral (M c 4) is the least reduced, as even Hensel pointed out. Now cases of atavism are not unfrequently met with in the horse, where the medial splint bone on the fore-foot has a digit more or less distinctly de- veloped. And as the hoof of this second digit never touches the ground, and, accordingly, is not worn off in any way, the horn- substance becomes long and irregular, precisely as in the case of the lateral toes (the second and fifth) in old cows. Atavisms of this kind on the hind- foot are of extremely rare occurrence. * When it was said above that the horse no longer shows any trace of rudimentary toes, this is not altogether correct ; the rudimentary hoofs do still exist. Thus the so-called " chestnut," a flat horny wart on the skin above the carpus, seems to corre- spond to the hoof of the lost thumb ; at all events, I found it in cases where a second digit existed. Another formation that must be included here, is the so-called " spur." This spur is a small cylindrical horny substance, which in our present horse is concealed by the hairy tufts of the fetlock. It seems to represent the coalesced horn- shoe of the rudimentary second and fourth toe of the horse. THE EQUID^I, OE HORSES. 207 ' During the sixth decade of the present century, there was exhibited in Munich a horse under the name of a " stag-horse," which had veritable hip- parion feet. The splint bones of the four extrem- ities had 'digits, that is, toes. The so-called " chestnuts " existed on all the four limbs, and were strongly developed, whereas all the four " spurs " were wholly wanting. 1 On the fore-feet the medial side-hoof (second digit) was most fully developed, on the hind- feet it was the lateral or fourth toe. As the side-hoofs of all the extremities did not reach the ground, and hence were not worn, they had grown to a considerable length, and were bent like horns. Such cases are of great rarity ; still they had been observed even in earlier times. The famous Bucephalus of Alexander the Great is said to have been an animal of this kind. Moreover, the atavism is said in some instances to have been transmitted to the offspring, which of course is very probable. It is more than probable that from a single animal of this description a breed of Hip- parion-horses might be reared. There would, 1 This observation would certainly support the opinion, which we are inclined to doubt, that the ' chestnuts ' and ' spurs ' were rudiments of the first, second, and fifth hoofs. If, nevertheless, I hold to my doubt, at all events as regards the atavism of the thumb, I do so because it would be a unique phenomenon. 2C8 THE MAMMALIA. however, be absolutely nothing to be gained by such reactionary measures.' The same indications of the transformation from Palaeotherium to our present Horse in an uninterrupted line from the Eocene to the present are manifested by the teeth. In connection with this point we must first of all mention Eiitimeyer's classic studies on this question, 1 which have been admirably supplemented by Forsyth- Major. Owen had already recognised the change in the formation of the jaw that accompanied the transformation of the organs of locomotion. The teeth of the Palseotheridse, which show less com- plicated folds of enamel, and are adapted for crushing juicy plants, gradually change into the pillar-shaped molars of the horse, which, owing to their strength and the foldings of enamel, are suitable both for grinding corn and for chopping gritty grasses. The principal parts of the crowns are given on the accompanying drawing (Fig. 37). Even from Owen's illustration it is evident how the complicated enamel lines of the horse's tooth originated from the simple tracings on the tooth of the Eocene animal. The much more careful 1 Riitimeyer, Beitrdge zur Kenntniss der fossilcn Pferde, 1863. THE EQUIDJE, OE HORSES. 209 comparisons of recent times have shown us these changes down to the minutest detail ; and from the geological series, which is being made more com- plete year by year, the complex formation of the horse's molars becomes perfectly intelligible from the outlines on those of the Palaeotherium. Riiti- Fio. 37. Eight Upper-jaw Molar of the Horse. a, i, t>, h, Outside, inside, front, back ; M, m, front, back crescent ; P, p, larger and smaller inner pillar ; F,f, inner main- and side-fold. After Brauco. meyer further gives special proofs that the species in question transmitted the relative peculiarities of their molars to the milk-teeth of their offspring and descendants, whereas the descendants trans- mitted the new inheritance specially to the molar teeth. p 210 THE MAMMALIA. It is only in its historical connection that the peculiarity of the horse's dentition acquires a peculiarly significant interest, and as in the case of the three-toed foot when viewed apart from the historical course of its development, seems simply an incomprehensible peculiarity, of no importance either to the horse itself or to the horse fancier . Palseotherium, Anchitherium, and Hipparion pos- sess, when full grown, seven cheek-teeth above and below on both sides of the jaw, p -, m r . On the other hand the normal formula in the horse's den- q q tition is p -, m -; it changes only three of its o o milk-teeth, and gets three other molars. Now it has long since been known to breeders and veterinary surgeons that, pretty frequently, the horse's row of cheek-teeth begins with one stump too many, the so-called 'wolf's tooth' (on Owen's drawing marked by the letter p). This most perfectly ex- presses the fact that it occupies the place where, in Palseotherium among others, we have the first premolar. When it appears in the horse, however, the wolf s-tooth ' is not deciduous. It is most obviously a tooth in the last stage of disappear- ance, an irregularly appearing descendant from the THE EQUID^E, OR HORSES. 211 days of a full dentition, and its disappearance probably stands in causal connection with the increased strength of the other teeth. Before discussing the American line of horses, let me here quote W. Kowalewsky's opinion regard- ing the connection between the genera mentioned above ; his remarks are as careful as they are con- vincing : ' Nothing is further from my intention than to maintain that the animal which we call Paltfotherium medium directly produced an Anchi- therium, the latter an Hipparion, and so on. But among the number of individuals which we call Palaeotheridse, there must always have been some forms which would incline more towards the Anchi- therium than the others. In the same way I have been able to determine owing to the large number of species I was fortunate enough to be able to com- pare that among the Anchitheridse a few still remained completely within the limits of the species> although they showed some characteristics by which they resembled the Horse on the one hand, and the PalaBotherium on the other. A few trifling flattenings of the bones, certain peculiarities of a joint which are met with in some individuals, are not to be found in others. Without doubt there was at one time a transition between two individuals which resembled p 2 212 THE MAMMALIA. each other most; but to expect, as is generally asked by those who believe in the invariability of species, that we should be able to show the last Palaeotherium, and his descendant the first Anchi- therium, is to demand an impossibility. An origin- ally normal characteristic sometimes begins not to occur, then it becomes unimportant, i.e. is found wanting as often as it occurs, then it appears rarely, and finally disappears completely. Thus, for in- stance, the small front premolar of Palaeotherium is smaller still in Anchitherium, but still occurs regularly ; in the Hipparion it is met with as often as it is found missing, and in our present Horses it is extremely rare (as the "wolfs tooth").' This very careful comparison of the differences in the dentition has been further worked out by Kowa- lewsky. 1 We have now again to turn to America, to the well-known fields of discovery to the right and left of the Eocky Mountains, where to all appearances a group of Odd-hoofed animals lies buried, much more numerous in members than the group in the Old World, showing no gaps, and terminating with the horse. Compare the table on page 190. The 1 W. Kowalewsky, ' Sur 1'Anchitherium Aurelianense Cuv.,' M6m. de I'Acadtmie imp. de St. P&tersbourg, 1873. THE EQUIDJE, OR HOESES. 213 line begins in the Early Eocene with the Eohippus of the size of a fox, which possessed, in addition to the four well-developed toes of the fore-foot, the remnants of a fifth. According to a remark of Marsh's, this animal, in foot and dentition, al- ready shows unmistakably that with it commenced the branching off of the progenitors of the horse ct W H in jii m FIG 38. Foot of the Fossil Horses of North America. a, Oiohippus ; 6, Mesohippus ; c, Miohippus ; d, Protohippus ; , Equus. from the other Odd-hoofed animals : * in the next higher division of the Eocene, another genus (Orohippus, Fig. 38) makes its appearance, replacing Eohippus, and showing a greater though still dis- tant resemblance to the equine type. The rudi- mentary first digit of the fore-foot has disappeared, and the last premolar has gone over to the molar 214 THE MAMMALIA. series. Orohippus was but little larger than Eohippus, and in most other respects very similar. ' Near the base of the Miocene we find a third closely allied genus (Mesohippus), which is about as large as a sheep and one stage nearer the horse. There are only three toes and a rudimentary splint bone on the fore-feet and three toes behind. Two of the premolar teeth are quite like molars. The ulna is no longer distinct, or the fibula either, and other characters show clearly that the transition is advancing. In the Upper Miocene Mesohippus is not found, but in its place a fourth form (Mio- liippus) continues the line. The genus stands close to the Anchitherium of Europe, but presents several important differences. The three toes in each foot are more nearly of a size, and a rudi- ment of the fifth metacarpal bone (of the second series) is retained. All the known species of this genus are larger than those of Mesohippus, and none pass above the Miocene. * The genus Protohippus of the Lower Pliocene is still more equine, and some of its species equalled the ass in size. There are still three toes on each foot, but only the middle one, corresponding to the single toe of the horse, comes to the ground. This genus resembles most nearly the Hipparion of THE EQUID.E, OR HORSES. 215 Europe. In the Pliocene we have the last stage of the series before reaching the horse, in the genus Pliohippus, which has lost the small hooflets and in other respects is very equine. Only in the Upper Pliocene does the true Equus appear and completes the genealogy of the horse, which in the Post-Tertiary roamed over the whole of North and South America, and soon after became extinct. This occurred long before the discovery of the continent by Europeans, and no satisfactory reason for its extinction has yet been given.' l So far Marsh, and, owing to the quantity of his discoveries, he proclaims the horse, above all the other hoofed animals, to be clearly a native of America. That the European line discussed above is more incomplete is very evident ; however, it must be assumed that with further discoveries the differ- ence will be equalised. And, indeed, an important beginning has already been made during the last few years. The gap between Hipparion and Equus, which clearly existed, and was filled up in the Ame- rican line by Pliohippus, no longer exists in the Euro- pean series either. For Forsyth-Major 2 has pointed 1 Marsh, The Introduction and Succession of Vertebrate Life in America (1877). 2 Forsyth-Major, ' Rivista scientifica industriale, 1876,' Kosmos, ii. 216 THE MAMMALIA. out that the races from the Quaternary period of Upper Italy, classed together as Equus stenonis, include all the required intermediate stages between Hipparion and our present Equus cdballus. It is of the utmost interest to be able to prove that in Equus stenonis the reduction of the side meta- tarsals preceded that of the tarsals : for while the metatarsals do not differ from those of our present horse, the tarsals show all the intermediate stages between Hipparion and Equus cdballus ; they have not yet had a sufficient length of time to accom- plish the complete change which renders the foot of our horse so eminently more suited to the activity of the one-hoofed animal than was the Equus stenonis. In fact, it may be affirmed that in the case of the Diluvial horses, the splint bone (i.e. the rudiments of the metatarsals n and iv) had not yet coalesced with the mid-foot, which coalescing of the bones occurs in our present horse with its seventh or eighth year. 1 1 Nehring remarks, on the other hand, that in our present horse, the splint bones do not coalesce nearly as often as is sup- posed, and that, for instance, among the skeletons in the Berlin collection, the coalescing is the exception, the non-coalescing the rule. That, therefore, the supposed difference between the Dilu- vial and the present horse is not an essential one, and that it need only be admitted that the coalescing of the splint bones occurs more frequently in the domestic horses of the present THE EQUIDJE, OB HORSES. 217 That the two groups, the European and the American, run parallel, perhaps without any inter- course during the longest of the Mid-tertiary periods, must not only be admitted as probable, but be granted as possible. The probable coloni- sation of America by the original inhabitants of Asia took place before they had learned to make use of the horse as a domestic animal. In America the Horse no longer existed then. It may be that the long-continued ice-formations of the Diluvium had forced it to leave the high- lying plains to which it had been accustomed, and driven it to regions where it succumbed in the struggle for existence. The Spaniards re- introduced the horse to the New World, and now it there also fulfils its mission as a companion to man if we may for once use a teleological ex- pression. In addition to all this, however, it must also be stated that the American members of the genus Horse have never advanced as close to our present horse as the Diluvial members of the Euro- pean family ; hence, that the true horse of our than in the Diluvial horses. Now, as Nehring, among other things, proves that the splint bones of the Diluvial horse, of Westeregel, are considerably larger and longer than they are usually found in the domestic horse, the circumstances we en- deavoured to prove above remain essentially the same. 218 THE MAMMALIA. day Equus caballus never existed in America before its importation. Branco l has lately pub- lished a very remarkable treatise on this subject. He has shown that in the Equus andium which lies buried in the volcanic tufa of Ecuador, and is of the same age as the Diluvial Pampas horses and the species found in the caves of Brazil the eye is placed considerably deeper, whereas in the Equus caballus it has moved considerably farther back. Here, again, it is our grand Goethe a naturalist not nearly often enough quoted, in spite of what an eminent Berlin orator may say who sixty years ago pointed out this ideal character of the horse from an artistico- scientific point of view, and thus anticipated the wearisome labours of palaeon- tology. Goethe's words are 2 : ' In the horse's head of the Elgin Marbles (of the Parthenon), one of the most splendid relics of the grandest period in art, the eyes stand out freely and are placed near the ears, whereby both senses, sight and hearing, seem to act together directly, and the sublime creature is enabled to hear as well as to see what is happen- ing behind it. It looks so majestic and spirituel, 1 Branco, Diefossilc Saugethierfauna von Punin und Ecua- dor, von Beiss und Branco. Berlin, 1883. 2 Goethe, Ueber die Anforderungen an naturhistorische Zeichnuncjen (1823). THE EQUID^E, OR HORSES. 219 almost as if it had been formed contrary to nature, and yet the artist has, in reality, given us a pri- meval horse, whether he saw it with his own eyes or conceived it in his mind ; to us, at all events, the animal seems depicted in the spirit of the highest form of poetry and reality.' The horse, in all its various forms of develop- ment, from the dwarfish pony to the Percheron and the huge English cart horse, has been regarded as a single species ever since it was found in the service of man. We talk only of different races of Equus caballus. The taming and breeding of horses may be said certainly not to have taken place for thousands of years after the time when man first came into contact with the animal. The period during which prehistoric Man, in Europe, fed chiefly upon horse flesh is that which has also been called the Eeindeer period, owing to the wide distribution of that animal. This division of time follows the period of the fullest development of the mammoth, and was in many localities e.g. in Central France extremely favourable for the in- crease of the genus Horse, in spite of an evidently rough climate. Nowhere in the world are such accumulations of remains found as near Solutre in the neighbourhood of Macon to the north of Lyons. 220 THE MAMMALIA. The lower stratum of this remarkable deposit con- tains a whole fauna of larger and smaller mam- mals mammoth, cave tiger, lynx, cave bear, brown bear, cave hyena, wolf, fox, polecat, marten, bad- ger, Canadian deer, primeval ox, horse, hare, and saiga-antelope. All the bones are broken and mixed up together ; and the rude flint implements likewise found there, also point to the fact that the grass-eaters fell victims not only to the teeth of the beasts of prey, but to the hand of huntsmen as well. In the upper strata the mammoth and his huge flesh-eating contemporaries disappear from the scenes. Primeval Man entered the Keindeer period from the Mammoth period, and thereupon horses were slain by the thousand. The opinion which found favour in France that the horse of Solutre had been tamed and domes- ticated is untenable, as has again lately been pointed out by Pietrement, who has carefully con- sidered the question in all its bearings. 1 Never- theless, the horse from Solutre is of great interest, as we most probably have in it one of the races which subsequently became domesticated, and which left descendants that probably still exist. The pieces 1 Pietrement, Les chevaux dans les temps prehistoriques et historiques. Paris, 1883. THE EQUIDJ3, OR HORSES. 221 of skeletons found at Solutre point to the so- called Ardennes horse, one of the long-headed races of the domestic horse. One feels tempted to look round and see whether there are not other horses that approach as close to the Solutre branch. In doing this we think, in the first place, of the small horse that lives in a semi-wild state on the Carmargue, in the delta of the Ehone. There also exist in Alsace the last offshoots of an old race of this kind. In stature and proportions these ani- mals resemble large ponies. The head, in the specimens which seem most purely to represent the race, is large and ugly, but the body, in spite of the want of actual care, is well formed ; the limbs very powerful. The animals, which are good- natured and easy to manage, perform extraordinary feats in the way of drawing weights. At times, when there is little work doing, they are kept for weeks in the meadows to the east of Schlett-stadt, and are met with, in fact, in other districts besides Schlett-stadt as far as the Ehine. To throw proper light upon this possible con- nection, it would be necessary to make the most careful examination and measurements of the various parts of the skeleton, and this has not yet been done. How this would have to be done has 222 THE MAMMALIA. been shown very recently by the distinguished authority on the Diluvial mammals of Central Europe, Professor Nehring of Berlin, in his ex- ceedingly interesting studies on the fossil horses of the German Diluvial deposits, and their relation to the living horses. 1 The Italian palaeontologist, Forsyth-Major, had, somewhat previously, in an admirable manner, compared the Diluvial horse in Italy with the present animal. In order to obtain a good starting-point for an investigation of this kind, it is necessary first to understand a few of the principal species of the domestic horse. Of these we require only the two groups in which, according to French investigators, the domestic horse appears, and into which, moreover, the eight races may be subdivided. In the horses of the principal Oriental race, the portion of the skull covering the brain is strongly developed, the facial part of the head is smaller, which circumstance is expressed mainly by the breadth of the forehead. The inner side of the crescents of the molars of the upper jaw (Fig. 37) has a covering of enamel with but few folds; the bones of the limbs are graceful, but of a very firm structure. An admirable represen- 1 Nehring, Fossils Pferde aus deutschen Diluvialablagerwigen und ihre Beziehungen zu den lebenden Pferden. Berlin, 1884. THE EQUID^:, OR HORSES. 223 tative of these qualities is found in the Arabian horse. ' The Occidental Horse,' says Nehring following Frank of Munich, who was the first to distinguish this main race ' shows itself, as regards the two first mentioned points, to be the exact reverse of the Oriental horse ; for its distinguishing character is the much larger development of the facial portion of the skull, as compared with the part covering the brain. The skull seems to be comparatively long and narrow with a small breadth of forehead. The rims of the eye-cavities stand somewhat for- ward. The enamel folds of the so-called crescents of the molars of the upper jaw are very complicated. The bones of the limbs of the Occidental horse are of a thick and massive build, while in structure they are less substantial and hard than in the case of the Oriental horse.' To this Occidental race, in Germany, belongs our common-middle-sized horse, which of late years has been more and more set aside to make room for a mixed race ; for the State and private persons have taken the breeding of horses into their own hands and introduced foreign animals, more par- ticularly of the Oriental species. Thus, for example, during some decades, crossings from the Arabian 224 THE MAMMALIA. breed, especially with the famous stud at Graditz near Torgan, was systematically encouraged in the districts on the Elbe in Saxony. The heavy horse of Central Germany has been termed the Equus caballus germanicus by Sanson, and by Pietrement after him. There were only uncertain conjectures as to its origin, yet the general opinion appeared to be that, like all the medium-sized and larger European races, it was of Asiatic origin, and that it had been tamed and introduced by different nomadic tribes in prehistoric times. 1 This question, which claims our whole interest, for it affects the history of the noblest of our domestic animals, has advanced one stage in clearness. Nehring has undeniably proved that a Diluvial horse of Central Germany numerous re- mains of which have been discovered at Westeregeln 1 ' The Roman authors, Caesar in particular, distinguish in Gaul and Germany between a native race of horses, which was small and unremarkable although hardy, and between foreign breeds that were larger and nobler in appearance. And many other writers of ancient and later times speak of foreign horses in contradistinction to the native breeds, so that there is, pro- bably, no doubt that there existed in those days, in Germany, two races strikingly different in outer appearance. That the small native race must be traced to the tamed wild horse of Europe, may probably be considered as certain, so that the only remaining question is, of what origin was that foreign horse, and whence did it come to us ?'' Al. Ecker. THE EQUID^E, OR HORSES. 225 nsar Magdeburg, and at Thiede in Brunswick tallies in all characteristic features with the heavy Occidental horse. Hence it had not been introduced, but had been tamed and reared by our ancestors from the wild race which they found there. This narrow-browed animal lived also on the Ehine, in the neighbourhood of Eemagen ; ' in the form of its skull and the rims round the eye-cavities it resembles our old medium-sized lowland races.' Nehring sums up his views regarding the Ger- man Diluvial horse and its relation to the present tamed and wild races, in the following passage of general interest : ' The Diluvial horse of our country, like that of the neighbouring European lands, was an untamed, wild animal which roamed about, and seems to have lived in especially large numbers in the districts round the Hartz Moun- tains. These districts, during one distinctly longer division of the Diluvial period, possessed a vegeta- tion of the steppe species and a corresponding climate. The forest had become greatly reduced during the Ice period (i.e. the first ice period, if we are to admit of there having been two). On these steppe-like tracts wild horses lived in large herds, together with jerboas, steppe-susliks, logamys, hare- rats, numerous wild mice, and other characteristic Q 226 THE MAMMALIA. inhabitants of the present steppes beyond the Volga. 1 ' Their existence was now and again endangered by a few isolated lions, also by wolves, whereas hyenas (remains of which are not unfrequently met with at Westeregeln) probably seized only the carcases and scarcely ventured to attack the live horses. 'The worst enemy of the Diluvial horse was man. We know by numberless investigations, that the human inhabitants of Central and Western Europe in those days lived almost entirely upon the hunting of horses ; the bones and teeth very probably the skins, hair, and sinews also were made use of in a variety of ways.' Nehring, whom we have been quoting, goes on to say how all this was done, what proofs we have of the occasional visit of nomadic tribes to certain localities, and how a regular system of breeding arose gradually from single attempts, and then adds : 'Those of my readers who are accessible to scientific proofs will, I hope, find my detailed com- parisons sufficient to convince them that an essen- tial portion of our so-called heavy (common) horses must be traced back to the heavy, thick-boned Diluvial horse.' 1 Compare above, p. 76, fol. THE PROBOSCIS, OR ELEPHANTS. 227 The horse from Solutre, and the thick-boned animal of Central Germany, are two local races very nearly related, but yet distinguishable. There is another race which has been found most com- plete round about Schussenried in south-western Wurtemberg ; it has been described by the eminent man of science, Fraas, who also gives an account of many of the other Diluvial inhabitants of that dis- trict. This horse is distinguished by its compara- tively broad forehead and by the gracefulness of its limbs, and hence agrees in important points with the Oriental domestic horse. Now there have been discovered in many of the prehistoric deposits of the Bronze period, the remains of a tamed, thin- boned horse, which has universally been supposed to be of Asiatic origin. It cannot well be doubted that this horse was imported by the tribes that overran Europe from the East; yet it is equally possible and probable, that a portion of the slimmer, tamed horses of the Bronze period had been pro- duced through the taming of the broad-browed Diluvial horse of South Germany. 5. THE PBOBOSCID.E, OB ELEPHANTS. The circumstances of nutrition which determine the general character of the dentition and of the 228 THE MAMMALIA, structure of the feet of animals, account for the fact that the trunked-animals have always been classed with the genuine hoofed animals ; but any attempt at a closer definition of the older system, with its many-hoofed animals and thick-skinned animals, always led to the isolation of the ele- phants. Their dentition shows no link whatever with those of the present animals. And in causal connection with the dentition we have the strange shape of the skull, and again connected with the latter the development of the proboscis, which in a wonderful manner counterbalances the weight and awkwardness of the head and neck. Probosces are met with in other mammals : thus we have the lip-finger of the rhinoceroses and the prominent lip and nose of the tapirs and of the saiga-antelope. Moreover, our excellent anatomist Burmeister (whether rightly or wrongly I do not venture to say) has equipped the Macrauchenia, probably one of the horse family from the Pliocene deposits of Patagonia, with an appendage resembling an ele- phant's trunk (Fig. 39). Be that as it may, at all events our present Ele- phant is one of the strangest and most enigmatical forms, which, moreover, must have impressed uncivilised nations in an extraordinary manner. THE PROBOSCIS, OR ELEPHANTS. 229 We do not put much faith in the Indian legend, according to which the monsters which the Great Spirit destroyed by lightnings, and which died without leaving offspring, were Mastodons (which existed in America as the earliest contem- Fia. 39. Macrauchenia patagonia. After Burmeister. poraries of man), still, A. W. Schlegel as early as 1883 ! pointed out in one of his classic inquiries that the influence exercised by the elephants upon the imagination of the Hindoos was positively all- ' A. W. Schlegel, Indische Bibliothek, 1823. 230 THE MAMMALIA. powerful. The Hindoos marvelled at everything in the animal, not only at its sagacity, which made it seem to them the embodiment of the god Ganesa, but also and more justly than we they admired the neatness of its feet. Its zoological singularity is, as already stated, mainly centred in the character of its head. To- gether with an unusually small breadth of head, the facial portion shows a remarkable height. The narrowness is caused by the very limited number of teeth. In the upper jaw there are only the two tusks (incisors) and one molar on either side ; in the lower jaw there are molars only, powerfully developed, it is true, but, as regards length, show comparatively far less dimension than is seen in the full dentition of a grass-eater. All the more powerful and higher are the roots, not only of the tusks but of the molars. The latter are changed six times, so that the succeeding teeth from be- hind and below claim a position in the inside of the jaw till the animal is tolerably advanced in years. The structure of the molar, even when worn smooth by use, shows it to be an exceedingly perfect apparatus for crushing leaves and grasses. Zoology terms it ' complex.' It appears to be formed of a large number of high and narrow THE PROBOSCID.E, OR ELEPHANTS. 231 cases of enamel which are filled with dentine and joined into one mass by cement. This account of the formation of the tooth, which is universally accepted by descriptive zoology, is, however, as we shall see, not correct, and very unnecessarily makes the gap which does exist between the Elephants and the other plant-eaters appear greater than need be. Even Cuvier distinguished among the Elephants a group of fossil trunk-bearers, perfectly of the elephant type, but with a more complete dentition ; the molars, although less large than those of the elephants, being characterised by nipple-shaped eminences or tubercles in pairs, forming a number of transverse ridges. Cuvier called the genus Mastodon. 1 A mastodon tooth of this kind (Fig. 40) presents nothing specially striking apart from its often remarkable size. The crown, however, is distinguished by the extraordinary strength of the connecting layer of enamel which does not pene- trate in folds into the interior. Now, as three molars of this kind with huge tuberculated crowns 1 The most important contributions on this subject are : Vacek, ' Ueber osterreichische Mastodonten und ihre Beziehungen zu den Mastodonten Europa's,' Abhandlungen der geologischen fteichsanstalt, vii. : most admirable also is the chapter on the Elephantoides ' in Gaudry's Mammiftres lertiaires. 232 THE MAMMALIA. are met with in a row at the same time (for instance, in the widely distributed Mastodon angus- tidens) ; and as, moreover, they follow upon one another as milk teeth and permanent teeth ; and, further, as several typical mastodons of this kind FIG. 40. The used Molar of Mastodon angustidens. a a', 6 V, c c>, Transverse ridges ; one-half nat. size. have, besides the upper tusks, lower ones as well, and between them other two smaller incisors, this species of dentition moves wholly within the limits and forms known to us. The mastodons referred to are those of the Middle and Upper THE PEOBOSCID^:, OR ELEPHANTS. 233 Miocene, which survived longer in America than in the Old World, and one of which continued to exist up to the period of the Diluvial deposits and turf formations, most probably even up to the prehis- toric times of the human race. This is the so- called Ohio animal, the Mastodon giganteum. FIG* 41. Portion of a Molar of Mastodon elephantoides. One-half nat. size. After Clift. As early as the Upper Miocene we meet with animals of the Mastodon species, with molars, the ridges of which are much more sharply denned and resemble rows of miniature roofs (Fig. 41), inas- much as they consist of numerous small tubercles, which almost coalesce with one another. The tops 234 THE MAMMALIA. of these tubercles become more or less rubbed off with age. Only in some cases are the furrows between the ridges of the tooth somewhat filled with cement. These differing varieties and intermediate forms have obviously proceeded from the earlier mastodons, and in order to simplify the arrange- ment have been classed as the genus Stegodon. Their home was chiefly in Italy, whence they spread abroad as far as Japan. 1 The discovery of their remains in the Japanese Archipelago is a proof that these islands did not lose their connection with the continent till comparatively recent times. These teeth prepare us for the molar of the true elephant, the latest form of the group. It originates and indeed not in theory but in the actual transition forms up to the living species by the ridges continuing to become steeper, drawing closer to one another, and sinking down almost to the root of the tooth, and by these furrows be- coming filled with cement, which thence covers the whole outward surfaces of the tooth. The enamel parts of the still unused tooth although in form and extent extraordinarily changed nevertheless show the same connection as in the species from 1 Naumann, Ueber japanische Elephanten der Vorzeit, Palceontographica, vi. 1882. THE PROBOSCIS, OK ELEPHANTS. 235 which we started. A comparison of Figs. 40, 41, 42 will make the homology of the spaces a a', b b f , c c' perfectly clear. Europe, before the appearance of the Glacia FIG. 42. Piece of a Molar of the Mammoth, cut longitudinally, Nat. size. f, Enamel ; d, dentine ; c, cement. period, possessed several elephants, and Britain, which at that time had not yet been rent asunder from the continent, possessed the Elephas antiquus, and Italy the Elephas meridionalis. The Mammoth 236 THE MAMMALIA. a l so _the Elephas primigenius, the most frequently mentioned and most widely distributed animal of the group had been driven from Asia into Central Europe, whether as far as England is still uncer- tain. It had an associate in the Elephas antiquus ; but in any case the mammoth survived it up to the period of man. Yet it can scarcely be said whether at the time the human immigrant took possession of Europe, and the struggle began between the tamed and the wild races, between man and the wolf in England, and the lion in Thessaly the mammoth was exterminated in this kind of struggle, or whether it succumbed to climatic, i.e. to natural influences unknown to us. 1 In entering upon a discussion of the elephants as a class, it was our wish to do away with what mystery seemed to encompass the existence of the present animal, and we have done so by pointing out their undoubted descent from the Miocene mastodons. There is but one other step backwards that we can take in explanation of the connection, by bringing forward another of the colossal, thick- skinned animals, the Dinotherium. Up to within very recent times only its skull was known (Fig. 1 Dawkins, The British Pleistocene Mammalia,' Palaonto- graphical Society, 1878, xxxii. ; Adams, 'Monograph on the British Fossil Elephants,' Ibid. 1877. THE PKOBOSCID^E, OR ELEPHANTS. 237 43), from which it was supposed to be a footless, aquatic animal, and that, by means of its two tusks which projected from the lower jaws and curved downwards, it probably moored itself to the shore while resting or sleeping. No whole skeleton of this animal has, it is true, yet been discovered in connection with the skull, but to judge from various remains of bones, which in all pro- bability belonged to it, it seems certain that the structure of the Dinotherium was of the Elephant species, and that Some kind Of pro- FIG- 43. Skull of Dinotherium gigan- boscis must be sup- teum " One twen *- fourth nat - size " posed to have been suspended from the elongated nasal bones. It is restored thus in our most eminent works on palaeontology, and the correctness of the supposition is confirmed by a comparison of the molars with those of the early mastodons. The form and manner of succession of these molars, five being able to be in use at the same time, lead to 238 THE MAMMALIA. the conclusion that the molars of the older masto- dons originated from those of the Dinotherium by the loss of one or more of the front milk-teeth as the result of the strengthening of the true molars. But as the known Dinotheridse and the earlier masto- dons occur in almost the same geological horizons, the supposed descent cannot, of course, signify that Dinotherium giganteum had changed into the Mas- todon angustidens, but only indicates the way where and how the mastodons have originated from ancestors of the Dinotherium species. As is evident from Weinsheimer's classification l our latest authority for the species remains of the Dinotherium, and more especially molars and lower jawbones, are found in various parts of the Old World ; but in all cases, only in the Tertiary deposits, and in no case higher than in the Upper Miocene strata ; it ranged from France as far as India. In England no traces of it have been found, and its southern limit in Europe is Greece (Pikermi). Notwithstanding the different forms and sizes of the teeth according to which fifteen species have been distinguished still, owing to the transitions met with everywhere, we are in- 1 Weinsheiraer, Ueber Dinotherium giganteum, K, Berlin, THE PKOBOSCIDjE, OR ELEPHANTS. 239 clined, with Weinsheimer, to assume only one species, the Dinotherium ; we are also glad to be reminded by him of Suess' words : ' We can readily convince ourselves that physical changes occur without the mammal of the district being much affected by them, but we find no change in the animal world without a change in the outward circumstances, without some recognisable episode.' The changes in the dentition of the Dinotherise (which appear somewhat earlier than the masto- dons) to the elephants proper, correspond with the gradual change in their food and mode of life. The DinotherisB and the older mastodons had to subsist mainly upon the roots and stalks of water- plants, which they tore up with their lower tusks in the morasses of tropical climes, like the rhinoce- roses. Harder grasses demanded and produced the transformation of the simple ridged tooth, the tuberculate teeth of the mastodons, the fall- ing away of the front milk-teeth, and finally a concentration of the material force, and more especially the peculiar conformation of the molar of the later and present elephants. 1 They certainly 1 ' All the changes of the organisation which we may observe in the later forms of Mastodon as compared with the earlier ones for instance, the different forms of the incisors, the re- duction of the symphysis (i.e. the connecting parts of the lower 240 THE MAMMALIA. have differentiated much more from the original form than the other plant-eaters ; but even in the case of these latter, a similar course from the general disposition to the specialised form of to-day has been pointed out. Thus, at the close of this short chapter, our elephants cannot any longer be said to stand as inexplicable wonders of creation. In the Middle Eocene deposits westwards of the Rocky Mountains, there have been discovered, among many other animal forms, numerous remains of powerful plant-eaters of the size of elephants ; their skull possessed two or three pairs of horns, and the upper jaw showed gigantic canines (Fig. 44). These Dinocerata are believed by Marsh and Cope (and with some degree of probability) to be de- scendants of the Coryphodonta (see above, p. 199), and although the possibility of their being related to trunked-animals is not excluded, still meanwhile it is a mere vague analogy. The Brontotherise from the Lower Miocene eastwards of the Rocky Mountains, which are likewise colossal creatures, half of the jaw), the increased slowness in the succession of the teeth, and the corresponding increase in the number of ridges, in short, the dentine which by degrees becomes worn off point to the fact that the later mastodons had discontinued the mode of life practised by their ancestors, and had adapted themselves to a life on land.' THE PKOBOSCID^E, OR ELEPHANTS. 241 but less striking as regards the formation of their skull, may, with somewhat greater certainty, be classed as a branch of the Ehinoceros tribe (see above, p. 199). Both groups, however, strike us nevertheless as somewhat strange, chiefly because their brain can be compared only with that of certain fossil reptiles, considering the size of the FIG. 44. Skull of Dinoceras mirabile. One-nineteenth. After Marsh. skull and the thickness and mass of the spinal marrow. It would seem to be a lower form even than that of the Marsupials and the Monotrema. Two other small groups are allied to the Hoofed Animals, but in regard to one of these, the genus Hyrax (rock conies), no more can be said to-day B 242 THE MAMMALIA. than what was known to Cuvier. Although the two groups, in their outward appearance and mode of life, show affinity to the Eodents with claw-like hoofs, their molar teeth are singularly like those of most of the Ehinoceros tribe. There is absolutely no safe starting point for their historical descent. 1 We are more fortunate as regards the class next to be considered, the Sirenia. 6. THE SIKENIA, OR SEA-COWS. 2 Of this group the dugong (Halicore dugong) lives in the Eed Sea, the Manatus frequents the West Coast of Africa, and another species the 1 Cope is inclined to think that the arrangement of the carpals in the Hyrax is a sign of very ancient descent. His main reason for this supposition is the fact that the bones form- ing the several rays of the fingers still lie one behind the other simply and regularly, as in the case of the lower vertebrates ; whereas in other mammals not, however, in the elephant the two rows of carpals have been displaced and lie side by side. The cause of this displacing or twisting must, without doubt, be looked for in the loss of the thumb, which again is connected with the cases of adaptive and inadaptive transformations of the carpals mentioned by Kowalewsky. As, however, in the elephants the row of carpals is not displaced, while in the Coryphodons a very marked displacement has taken place in spite of the thumb having been retained, it seems to me that Cope's attempt to arrange and determine the general relationships of the Hoofed Animals, more particularly of the earliest Eocene fauna, from these circumstances, is much too unsafe. 2 Lepsius, Halitherium Scliinzii. Darmstadt, 1881. THE SIRENIA, OR SEA-COWS. ' 243 eastern shores of America. Another and fourth species of very remarkable form, the Rhytina stelleri, belonged to our present period, but owing to the smallness of the range of its distribution, seems to have become extinct between the years 1741-48. The earlier systems of zoology considered the want of hind legs in Whales and the Sirenia,, the paddle- shaped form of their front limbs, and! the formation of the end of the body into an horizon- tally extended fin, to constitute the characteristic features of a distinct order of animals, compared with which other very marked differences in their skull and dentition seemed of little importance. However, nowadays we are so well acquainted with the disappearance of the front or back limbs, or of both extremities (in the case of reptiles) as phenomena of convergence, without this being considered a proof of any near blood- relationship, that we no longer think of classing the Sirenia with the Whales simply because of the want of the hind limbs. The Whales are flesh- eaters, the Sirenia plant-eaters ; the former, by their relationship to the seals, belong to the order of the Fera, flesh-eaters in the narrower sense of E 2 244 THE MAMMALIA. the word ; the latter are a very ancient branch of the Hoofed Animals. Of the living Sirenia the Manatus shows the fullest dentition with a change of teeth. It points to an old Tertiary group found in Jamaica, the Prorastomus sirenoides, whose molars are genuine ridged teeth. The other and more perfect line ends in the present period with the so-called Steller's Sea-Cow (Rhytina stelleri), which has recently become ex- tinct. It had no true teeth for masticating pur- poses, but, in place of molars, had large fibrous structures on the gums, one on each side of each jaw. These structures occur also in two of the living species, but are less large. The dugong already shows a considerable loss of teeth, but by possessing them stands nearer to the earlier form of Sirenia, which leads in a direct line back to the Eocene Halitherium. The dental formula is : _ When comparing the genuine Hoofed Animals with their ancestors, it was seen that the loss of one or two toes took place as early as in the first Tertiary division. It was only single genera, such THE SIRENIA, OR SEA-COWS. 245 as Coryphodon, that still showed the old five-toed extremity, an inheritance from Pre-Tertiary times. However all the living Sirenians possess a five- fingered hand. When, therefore, it is said that the molars of Prorastomus are genuine ridged teeth, these do not point to the true Lophiodonta and tapirs, with their already reduced hand, but to earlier ancestors on both sides. Thus things no longer existing point to that very distant past, which extends back beyond our actual observa- tions. Even in the case of Halitherium all that is left of the hind limb is the thigh-bone. This bone, however, is still attached to the pelvis, which is tolerably reduced, but has a socket. The earliest Sirenians, therefore, had a less striking form of skull, but, nevertheless, in their whole appearance were already like the present living species. From this it follows that the four- footed mammals changed their abode for the sea, and lost their hind limbs, before the Tertiary period. The living Sirenians have experienced a still farther reduction of the pelvis ; it has become de- tached from the vertebral column ; and even the above-mentioned remnant of the hind limb, the rudimentary thigh-bone, has wholly disappeared. 246 THE MAMMALIA. 7. THE CETACEA, OK WHALES. Up to about the year 1840, our scientific knowledge of the larger Whales was based almost exclusively upon the dissection of a few stranded animals made in most cases in a very superficial manner. Skeletons of the animals could, of course, be procured, and some complete specimens had been set up in some of the museums. Their ribs, lower jaws, and vertebrae had also been collected, and, like the bones belonging to fossil elephants, were chained to town-halls and churches, where they were gazed at as the remains of giants, and pro- bably also (as was the case with a mammoth's thigh bone in Spain) were worshipped as the reliques of saints of giant stature. Owing to this manner of acquiring scientific material, a fatal confusion had arisen in the names given. It was about this time that Eschricht, professor of physiology in Copenhagen, applied the well-known lines ' If thou the poet would'st under- stand, Then must thou go to the poet's land,' to the Cetaceans. He did not visit them himself, it is true, but his friend Holboll, who was for many years inspector of the Danish colonies in Green- land, undertook, at Eschricht's request, to make THE CETACEA, OR WHALES. 247 collections and observations on the shores of the Arctic Ocean. Holboll furnished the museum of Copenhagen with excellent material in the way of skeletons, together with the softer portions of the body, also whole animals of various ages, with detailed accounts of the biological observations he had made. All this information Eschricht 1 made use of in a classic work, where he traces the trans- formation of the skull of the foetus (only some few feet in length altogether) to that of the full-grown giant, that framework which strikes the on-looker at first as perplexingly strange. He cleared up the relation between the bearded and the toothed Whales by following up Geoffrey's discovery more minutely, i.e. by showing that the foetus of the Bearded or Whalebone whale possesses a number of small teeth, which never cut through the gums, and subsequently become completely re-absorbed, when the huge sieve-like apparatus on the mucous membrane of the gum appears. The rudimentary teeth of the Whalebone whales, which never come into use, are 1 Eschricht, Zoologisch-anatomisch-pkysiologische Untersuch- ungen ilber die nordischen Walthiere (Leipzig, 1849), of which work there is an English translation ; also Brandt, ' Untersuch- ungen iiber die fossilen und sub-fossilen Cetaceen Europas,' M#m. Acad. Petersb., 1873 ; Van Beneden et Gervais, Ostiographie des Cetacte. Paris, 1868-80. 248 THE MAMMALIA. final links in the chain of evidence that the Whale- bone whales are the last members of a transformed group which commenced with animals with four toes and numerous teeth, and which by the gradual diminution of the dentition have become Whale- bone whales. Still, the skull of the Whalebone whales shows so much resemblance to that of the Dolphins and all of the other toothed whales, that, were it not for the discovery of teeth in the foetal animal, we should be in doubt as to the unity of the two groups. From the head of a dolphin only a few feet in length, we may learn all about the peculiar trans- formations just as well as from the head of a Greenland whale. The mid jawbones (Fig. 45) do not appear in front between the upper jaw- bones, but are very much elongated, and fre- quently lie somewhat irregularly, projecting beyond the upper jawbone. The most striking changes, however, are those of the middle head, and all this can be traced to the rising up of the nasal cavities in all other mammals these lie horizontally or obliquely towards the front which form perpen- dicular blow-holes close to the crown oi the head. Not only has the olfactory bone become raised, but the nasal bones also, in most cases, have been completely displaced from their position as THE CETACEA, OE WHALES. 249 coverings, and stand as perpendicular back walls to the nose, while the frontal and parietal bones are compressed and pushed aside in the most remark- able manner. However, it would certainly not re- quire a practised osteologist to construct the skull of a whale from any certified bone. There is nothing in the skull of the whale that could, in the FIG. 45. Skull of Delphinus lagenorhynchus. Gray. 1 1, Mid-jawbones ; o t, upper jawbone ; j, cheek-bone ; p, parietal ; s, frontal bone ; n, nasal bone ; e, olfactory bone. One-fifth nat. size. slightest degree, lead to a connection between it and the Sirenians (p. 243). Nevertheless, their hind limbs, like those of the Sirenians, have disappeared externally without leaving a trace of their former existence; the rudimentary pelvic bones that are concealed in the flesh sometimes with the last rem- nant of the thigh-bone, very rarely with the shank 250 THE MAMMALIA. bear witness, however, to their having possessed an- cestors with four legs. 1 The front limbs remain wholly within the known structure of the mammal leg, as may be seen by that of the dolphin on Fig. 46. The toothed whales are almost without excep- tion five-fingered, even though in most cases the thumb and the little finger appear very much reduced. This, moreover, shows them to be geologically older than the Whalebone whales ; for of these only the smooth whales (Balcena) possess five fingers ; in the others the thumb has completely dis- 1 The modifications which the whales have experienced as mam- mals in water, have been admir- FIG. 46. Eight Fore-limb of ably described by Prof. Flower, Delphinus delphis. After ' Whales in the Past and Present,' van Beneden and Gervais. Kosmos, vii. 1883. THE CETACEA, OR WHALES. 251 appeared. That the Whalebone whales are geologi- cally younger than the smooth whales is likewise proved by their generic characters, the furrow which extends from the throat to the belly, and the humped or fin-shaped protuberance on the back. Hence not only does the preserved skull of one of the most important group of the Whalebone whales (the Cetotherium) oblige us to maintain the animal to have been one of the smooth whales, but we are also enabled, from this circumstance and the geo- logical period, to conclude that these whales did not possess either furrows on their breast or fins on their back. The time of the fullest development of the Cetacea belongs to the Miocene period, when they had associates in the large and also numerous small Whalebone whales, for instance, the Cetotherium just mentioned, which is closely related to the present Bearded or Whalebone whales (from two to ten feet long), and also the Dolphins and the Zeu- glodonta. The last-mentioned group is formed of the two entirely extinct genera, Zeuglodon and Squalodon. Brandt has in detail urged it as improbable that Zeuglodon, as is often supposed, can be regarded as an intermediate form between the 252 THE MAMMALIA. seals and whales, the shape of the skull and the strong nasal bones covering the nasal cavity having been thought to indicate this. Their length varies between twelve to seventy feet. They belong in America to the Eocene, in Europe to the Mio- cene period. Squalodon approaches closer to. the Dolphins than does Zeuglodon, more particularly by the position of the nasal bones and the corresponding displacement of the other bones. Its teeth (Fig. 47), like those of the Zeuglodonta, remind one of 31 4 the Seals. The dental formula is : i -, c -, pm . 17 m -. The compressed molars, which are pyra- midical in form, show a certain external resemblance to the teeth of the Sharks. As the Zeuglodonta including the Squalodonta are not yet as far advanced in the transformation of their skull as the Delphinidae, it has never oc- curred to anyone to regard the Dolphins as ances- tors of the Zeuglodonta. Such a supposition would be as irrational as if we were to imagine the Antelopes descended from Oxen. On the other hand, however, as great a difficulty would have to be faced were we to suppose that animals of the Squalodon species had left descendants of the THE CETACEA, OR WHALES. 253 Dolphin species. We do not speak of the dolphin- like whales with reduced dentition e.g. the Nar- whales ; these are side branches of the main stem, the members of which are distinguished by numer- ous teeth of the same shape. The teeth are always growing -and have no closed roots, wherein they resemble those of many of the reptiles. Now Baume, for various good reasons, has made it seem probable that the ever-growing teeth of mammals are an ancient inherit- ance, and that rooted teeth, on the other hand, are a new ac- quisition. If Baume is right in this, we have no connecting link for the Dolphins, and naturally none either for the Whalebone whales. All the three subdivisions Zeuglodonta, Dolphins, and Whalebone whales are found side by side in the Early Tertiary period, and the vertebrae of whales have even been found in the Jura. How- ever, all that can be said with certainty is that we FIG. 47. Tooth of Squalodon. a, From the outside ; 6, from the side. After SUss. 254 THE MAMMALIA. have no idea in what period or under what circum- stances whales came to be developed. What is improbable is that they were descended directly from reptile-like ancestors, independently of the other mammals. None of their peculiarities point directly to the Eeptiles, and are all intelligible as modifications which were effected by the land animal in its transition to a life in water. But of what kind were these ancestors ? Our first thought turns to the Seals, which, of course, have likewise adapted themselves to an aquatic life. However, in their case, the hind limbs have not in any way become reduced, and have only changed their position to the pelvis ; whereas the upper and lower parts of the leg are shortened, and the feet have become broad and lengthened paddles. Hence it cannot be imagined that these animals, which are so admirably equipped for swimming, could have struck out a new kind of adaptation. There could not have been any use or necessity for this. Hence a certain resemblance in the teeth can only have been the result of convergence ; and Prof. Flowers reminds us that this had long since been pointed out by Hunter, 1 who says : 1 John Hunter, ' Observations on the Structure and Economy of Whales,' Philoso. Trans. 1787. THE CETACEA, OR WHALES. 255 ' There are numerous points in the structure of whales which bring them much closer to the hoofed animals than to the beasts of prey for instance, the complex stomach, the simple liver, the respi- ratory organs, but mainly the reproductive organs, and the stages relating to the development of the foetus. Even the skull of Zeuglodon, which we admitted shows a certain likeness to that of the sea dog, shows as much agreement with that of the earliest pig-shaped ungulates, except in the purely adaptive character of the form of the teeth.' The objection raised that whales are flesh-eaters, while most of the Hoofed Animals are true plant-eaters, has been very properly refuted by Prof. Flowers, who points to the former predominance of omni- vorous animals, and shows that, with the exception of the Pigs, which have remained most faithful to the ancient type, the Omnivora became more and more true grass-eaters, while the others developed a taste in an opposite direction. Regular flesh- eaters can either not accustom themselves to vegetable food at all, or only in cases of emergency as we ourselves see daily with the cat or dog whereas we not unfrequently find instances of the contrary. Cattle eat dried fish with evident relish during a northern winter, as is well-known ; 256 THE MAMMALIA. and, therefore, the whales may, in the widest sense of the word, be classed with the primary Hoofed Animals, which still possessed five toes and differed as much, and even more, from the present group as the primeval horses from the horses of our day. The period when whales were most abundant was that of the Middle Tertiary, when, as already stated, the present Europe-Asiatic continent was for the most part under water. Brandt gives a very graphic description how the Cetacea of those temperate zones may have ceased to exist with the disappearance of that ancient ocean. And as the account is of general importance we will quote his words : ' The dying out of marine animals appears at first sight more strange than the dying out of land animals. We are apt to imagine that the in- habitants of the sea in their far-reaching element animated everywhere more or less by living creatures have a better opportunity of withdrawing from such external influences as affected them injuriously, without thereby experiencing a want of food, par- ticularly if the hurtful changes were not sudden. As an example of an earlier ocean of this kind, extending from Western and Southern Europe to Central Asia, we may take the immense ocean THE CETACEA, OR WHALES. 257 which existed in the Miocene, and probably lasted beyond that period ; when largest it extended to the Arctic ocean, and also communicated with the tropical seas in the, south. An ocean of this kind would not only confer a higher temperature upon the central zones, but would also essentially con- tribute to the warmth of the northern regions, and further, would not merely favourably affect the flora, but likewise give the fauna a very different character to what it shows nowadays. This con- dition was, however, by no means a permanent one. The gradual rising of the land led to a separation of the southern, sub-tropic or tropic seas, and to a lessening of the extent of the great ocean itself, and its temperature would likewise decrease. This was still more the case, however, with the great connecting sea in the north, more particularly when its separation, and gradual dis- appearance, resulted in its becoming more or less detached basins. The former luxuriant and fuller vegetation and animal life on the continent, which had been favoured by a warmer and moister climate, changed their character and became less exuberant. Less organic matter being produced on the land, less was carried to the ocean, where it served numerous small marine animals as food, 258 THE MAMMALIA. while, at the same time, the afflux of fresh water exercised a greater influence upon the lessened amount of sea water. These circumstances, which reduced the food of marine animals nay, which was obviously detrimental to their existence were accompanied, moreover, by the gradual separation of the great ocean into numerous basins, occasioned by the rising of the land already alluded to ; this prevented the animals from migrating, and the altered condition of the water increased even further owing to the separation. As a proof of this we have the Black Sea, the Caspian, and the Aral Sea, which remained longest in connection, and several other seas in Central Asia. Those species of invertebrates and fishes which, owing to their peculiar organisation, could exist only in large, open seas, and not in an inland sea with a lesser amount of salty substances, and were unable to accommodate themselves to the change in the physical, thermal, and biological conditions, died out together with the Cetacea. Those that sur- vived and were able to adapt themselves to circum- stances, like some of the molluscs, &c., decreased in size.' THE CAXIDJE, OR DOGS, 259 8. THE CARNIVORA, OB FLESH EATERS. The group of our present flesh-eating mammals which has been most carefully examined as regards specialisation of the dentition, and whose geological appearance has perhaps left most traces and points of connection is that of the Dogs, or Canidce. We shall, therefore, take this group as the starting- point for our comparative examination. The dog, like all the other Carnivora, possesses five toes on its front feet and four on the hind feet, with non-retractile claws. Those who wish to obtain even a limited view of the relationship between the main genus Canis and some of the sub-species,, and various other forms allied to these y their geographical distribution, &c.,. in the hope of finding some indications of the lines which partly vanish into primeval times with- out leaving any trace, but again in many in- stances showing a connection with definite palae- ontological facts, must first of all make them- selves acquainted with the dentition of the group. One tooth more or less unmistakably determines the date of one or more of the geological periods- The position, size, and disappearance of the teeth in- dicate, with almost the same certainty, the relation- 260 THE MAMMALIA. ship between the species which ranged separated over half of the earth's surface, or they point to the different origin of those which live almost within the same range of distribution. The certainty with which a palaeontologist works by making use of means which appear absolutely valueless to an unscientific person can be appre- ciated only by those who have acquired at least some knowledge of the way in which the work is accomplished. This again shows what little weight can be placed in the perpetual assertions of un- scientific persons, that the followers of the theory of descent are not in the position to prove the transformation of species. Everyone knows that the dentition of the fox (Canis wipes) consists of very differently formed teeth (Fig. 48), which, however, agree in so far that the crowns show an unbroken covering of enamel ; in this the molars, more especially, differ strikingly from those of the Hoofed Animals and many of the Eodents, where the crowns have com- plicated folds of enamel. The dental formula is : i c -, pm m For our purpose here o 1 43 it is the molars almost exclusively that come into consideration, hence 4 - : ^ . Thus the genus Dog THE CANID^E, OR DOGS. 261 has in the upper jaw four premolars or teeth that have replaced the milk-teeth, and two molars. Of the premolars the fourth (p*)is remarkable owing to its size, compressed form and sharp edge, also by possessing an inner process in front ; this is the carnassial or ' flesh-tooth.' Corresponding with it FIG. 48. daw of the Fox. After Huxley. below we have not the p*, but the first of the three molars or grinders, m 1 . The connection and origin of the different species of Dogs is determined by the, in some cases, undistinguishable shades of difference in the tubercles and processes, by the distances of these points from each other, and by 262 THE MAMMALIA. the length and breadth of the teeth, the measure- ments of which have to be made by the tenths of millimetres, and thus we finally have an animal of the dog species of the present day not with , but with molars, and we may there- fore draw the very probable inference as to the Eocene ancestors of the present Canidae. In the above remarks we have principally followed an ex- tremely clear account given by Huxley. 1 If several small differences are taken into con- sideration, the various species of the genus Dog (Canis) may be formed into two groups, the one represented by the Common Fox, the other by the Brazil fox (Canis azarce). These differences relate to the frontal depressions which are entirely want- ing in the fox and are strongly developed in the other group and to the form of the front part of the brain. By the side of the fox we have Canis fulvus,argentatus, littoralis,zerda, lagopus and others; on the other hand the Jackals and Wolves, all varie- ties of the Domestic Dog, Canis anthus, latrans, an- tarcticus, magellanicus, cancrivorus, varieties of the Dingo. In both groups subdivisions have again to 1 Huxley, ' Cranial and Dental Characters of the Canidae,' Proc. Zool Soc., 1880. THE CANID,E, OR DOGS. 263 be made in accordance with the form and strength of the carnassial tooth. However, even when a good idea of the Fox and Wolf type has been ob- tained, the differences finally merge one into the other, and thus here again comes an end to all systematic arrangement. In all the above-mentioned animals of the dog o species the dental formula of the molars is -. The o agreement of the lobes, processes, and tubercles of the teeth is such, that blood-relationship appears certain if the alternative of convergence or inherit- ance is properly considered. We must now refer to the question of the origin of the domestic dog. 1 That the whole line of foxes has nothing to do with the dog has long been an esta- blished fact. On the other hand, Darwin endea- voured to prove that various wild tribes of men in different parts of the globe tamed native wolf-like animals, and that the crossings of these species and breeding of various kinds produced the domestic dog of our day. This opinion of Darwin's has been somewhat modified by L. H. Jeitteles, a careful authority on the domestic animals. According to 1 Darwin, The Variation of Plants and Animals under Domestication ; Jeitteles, Die Stammv&ter unserer Hunde-Rassen. Vienna, 1877. 264 THE MAMMALIA. him the wolf (Canis lupus) has no connection with the European and west-oriental races of Dogs, the connection being mainly through the Jackal and the Indian Wolf (Canis pallipes). The races partly lead back into prehistoric times. Closest to the Jackals we have the so-called Turf-dog, known from the turf deposits of the lake dwellings, and which is probably the ancestor of our Pomeranian dogs. Allied to it we have the terriers and turn- spits. From Canis pallipes is descended the so- called Bronze-Dog, which most probably came to Europe with human immigrants from Asia, and with it the sheep-dog of Central Europe, the larger sporting dog, the poodle, cur-dog, and bull-dog. The ancestor of a third group may perhaps be found in the large jackal (Canis lupaster) of North Africa, to which we should also have to refer the ancient Egyptian dog, the Oriental street dog, and the wild dog of Africa. This does not as yet settle the question as to which fossil forms may be concealed among the numerous races of the domestic dog. Various con- jectures have been made, none of which, however, are based upon any special reasons. According to Blainville's opinion, a Diluvial species of a gentle and sociable nature no longer existing in a wild THE CANIDJE, OR DOGS. 265 state must have been the primeval form of the domestic dog ; but after what has been said above, this general way of settling the question must be regarded as one that no longer holds good. Wold- rich's l views show a greater amount of probability, and have lately been taken up again ; he maintains that our domestic races are descended from several wild forms of the Canidae of the Diluvium, and herein he agrees with what Darwin and Huxley have stated regarding the relation between the Domestic Dog and the living Jackals and Wolves. It may with certainty be maintained that the direct ancestors of the European Wolf are to be found in the Diluvial deposits. Formerly a huge animal of the wolf species was distinguished as the Cave Wolf, without there being any distinct character to separate the two forms. A third form of wolf Canis suessii, from the Loss near Vienna is de- scribed as a slim but powerful animal, strong enough even to pursue and overpower the larger species of plant-eaters. It is, in fact, one of the eight species of wolves which can be distinguished during the Diluvial early ages of man. And in addition to these there are about five kinds of foxes. 1 Woldrich, ' Wilde Caniden des Diluviums,' Wiener Denk- schriften, 1879. 266 THE MAMMALIA. In now returning to the living Canidse, several species demand our attention, one of which is described as Icticyon venaticus, a native of Brazil, the other under the generic name of Cyon, inhabit- ing the countries to the north and north-east of the Altaian mountains. These dogs do not possess the third molar in the lower jaw, and the m in the upper jaw is so small that a reduction appears to be immi- Fio. 49. Lower Jaw of Icticyon. After Huxley. nent there as well. It is in the natural course of things that one or both of the first premolars, or the last molar, should become useless and forced to disappear, by the neighbouring teeth being specially taken into requisition, although in most cases we do not know the immediate reason of this. 1 The 1 Any of our readers who can examine the head of a dachn- hund may convince themselves of the fact that the first pre- molar above and below can scarcely be of any use to the animal ; THE CANID^E, OR DOGS. 267 other circumstances of the structure of this group do not lead us to expect anything special from this concentration of the dentition. In former times, however, as we shall soon see, a most varied develop- ment of new genera of Beasts of Prey began with dog-like animals. Much more interesting for the purpose of our investigation here is the Otocyon lalandii, the spoon- dog of South Africa, so called from the peculiar formation of the skull. Its habits show an approxi- mation to the Foxes, yet as regards dentition it does not show this affinity, inasmuch as it possesses - : - molars, and also shows the most remarkable 4 4 differences in the relative size of the single teeth. As already said, the spoon-dog is in many ways, and as regards dentition, shaped after the fashion of the dog type, and can thus scarcely be dragged out of this connection, and we are compelled to look upon it as a still existing primary form of dog. The whole palaeontology of the Vertebrates shows that the many-toothedness of Mammals is an inheritance from their lower ancestors, and that it is a little stump which does not come in contact with the opposite row of teeth, and is frequently wanting altogether. If the dachshund is not forcibly suppressed as a species, its denti- tion will one day inevitably be reduced by one premolar. 268 THE MAMMALIA. any increase of the teeth within a class has prob- ably never taken place. o o As our dogs, with their - : - molars, have no 3 3 doubt been descended from fuller-toothed animals, Otocyon must be regarded as the still living representative of the early type of dog, which in other characteristics shows more affinity to the fox family. But as there also exist species of the group Canis azara with very small frontal depressions, it is, as Huxley says, very difficult not to imagine that these too must be traced to ancestors of the Otocyon type. From this species, therefore, we should have to derive the two lines which diverge into the fox on the one hand, and the wolf on the other. We are supported in this view by the observation that the South American Canis cancrivorus often pos- sesses the m 4 , and thus shows itself to be another remnant of the primary form. A fourth super- numerary molar of this kind is not a monstrosity or pathological phenomenon, but an atavism or reversion of the same sort as the so-called wolfs tooth in Horses, which was explained as a pre- molar which existed in the primary genus Anchi- therium. Hence the key to the derivation of all the Dog THE CANID.E, OR DOGS. 269 tribe is to be found in their relation to the spoon- dog. What Huxley states regarding the simi- larity between its dentition and that of the lower bear-like genera is certainly well worth conside- ration, but is of less importance than the con- clusion he draws from a discovery of his own. In several hundred different species of Dogs he found fibrous formations which are said to corre- spond with the marsupial bones (ossa epipubica), the distinguishing feature of the Marsupial group. If this observation becomes an established fact, the direct descent of dogs from Marsupials would seem in the highest degree probable. However, as one of our first comparative anatomists has maintained, we still require further proofs for Huxley's observa- tion. In imagining the Dogs connected with the Marsupials we should not, in the first instance, have to consider our present carnivorous Marsu- pials (Thylacinus, Dasyurus), whose row of molars consist of one tooth less than that of Otocyon, O A and are generally characterised as p , m -. The 4 4 Marsupial Rats would more likely have to be taken into consideration. They are the only known animals from the Eocene with four molars. More- over, by using the flat part of their hands and feet, 270 THE MAMMALIA. and possessing pointed, tuberculate molars, they point to the Insectivora. For another circumstance to be considered is, that various peculiarities in the teeth of the lower Canidae show approximation to the dentition of the Insectivora ; and the occurrence of rudimentary clavicles and the rudiment of a fifth toe on the hind limb, also clearly point to ancestors with well-developed clavicles, and the full number of five toes. All this is found united in the Insectivora : hence our present dogs have been traced back to the Eocene and Pre-Eocene Insect- eaters with certain peculiarities of the Marsupials. This derivation of the Dog tribe which is based mainly upon deductions from the present nature and distribution of the group goes back, therefore, into that dim twilight which, in the opinion of Cuvier and his followers, could alone precede the dawn of true light in the mammal world. We shall have to dwell a little in this Eocene period and look around among the incredible wealth of mammal forms, which seem, as it were, to have been re-animated by Filhol's graphic descriptions (see above, p. 64). We shall obtain some idea of the vigour of that exuberant, plastic life if, in place of the few Carnivora that are now inhabiting France, and indeed Southern and Central Europe, we ima- THE CANID.E, OR DOGS. 271 gine in one part of South-western France, of Garni- vora alone, some forty species from the size of the marten up to that of the most powerful wolves and bears. They lived, as the vast quantities of their remains testify, partly in herds ; and of food there was an abundance in the corresponding numbers and varieties of plant-eaters. First of all comes the Viverrine Dog (Cynodictis), which, although possessing the dental formula of the Dog .31 4 2 yP*y*ir (of which, in the upper jaw the fourth premolar, in the lower jaw the first molar stands for the carnas- sial tooth) had a very narrow skull, with broad, strong cheek-bones an admirably developed beast of prey between the size of a fox and a wolf. These animals, Filhol says, are curious and very peculiar forms, in which, after a very careful ex- amination, certain points are at length discovered by which they show affinity with our present Carnivora. But in spite of every effort to bring them under one head, it cannot be done. And hence we have to assign to them an essentially distinctive character, a position outside the cus- tomary classification, and one, in fact, which 272 THE MAMMALIA. approximates the living families. The French investigator means to say that they are dog-like animals, but not dogs ; that, in fact, they cannot be classed with any one of the present families of Carnivora, although showing the character- istics of the class in the various parts of their skull with which we are very well acquainted the mid jawbone, gums, alar processes, tympanic bones as well as the form of the skull as a whole. We should not exactly say that the animals stand be- yond our system of arrangement, but that they do away with existing gaps. This is most obviously the case with their dentition. In most of these forms of Cynodictis which can be defined as species the teeth are all well marked and developed according to their position. But in Cynodictis inter- medius, the last lower molar, m 3 , is so small that it is evidently of not much use, and we may rely upon its gradual disappearance. Were this to happen we should then have the dental formula of the Viverrse. And it does happen : the race named Cynodictis intermedium viverroides from the C. inter- medius has become a Viverra. With the loss of that molar there arises a small modification, p 4 , hence one connected with the im- portant carnassial tooth of the lower jaw; and THE CANIDJE,'OB DOGS. 273 what is most remarkable, the same loss is met with in two other species (C. crassirostris, leptorhynchus), the same modification of the carnassial tooth. It is not known what change in the mode of life caused these same changes in the teeth in several different sp.ecies. We are content with knowing in what manner so-called new species and genera appear on our earth ; in fact, not suddenly, but by imperceptible shades of difference, which in- crease in the course of thousands of generations, until, finally, what seemed at first an exception to the rule becomes the prevailing state of things. The objection so frequently brought forward that these ' accidental ' deviations would always again be neutralised by crossings with unchanged members of the species if geographical isolation did not come to assist them have no founda- tion whatever ; for our discoveries in palaeonto- logy prove the contrary. It must be remembered that the expression ' accident ' applies only in so far as it conceals our ignorance of causes and occasions. In many cases for instance, in the transformation of Mastodons into Elephants we can with some certainty determine the altered conditions of food to which the teeth had to adapt themselves. 274 THE MAMMALIA. And in the present case we have only to deal with an established fact, that the Viverrce are the descendants of the Viverrine Dog, Cynodictis. There can be no dispute about this. Hereupon commences a new series of modifications, and from the Viverrae are descended the Weasels. We now pass from the Upper Eocene of the phosphate of Quercy to a somewhat later period, which produced the Lower Miocene deposits of Saint Gerard le Puy, on the Allier. Here is found the Plesictis, a carnivorous animal distinguished from the Viverrse mainly by the form of its head. Filhol points out that a ' comb ' (crista) of the sagittal suture not previously existing, has been formed by a contracting of the temporal ' combs ' of the Cynodictis ; in other words, that we have the perfectly justifiable conclusion that smaller species of Cynodictis passed over into the form of Plesictis under the influence of natural causes. In the races directly descended from Cynodictis a change takes place in the nature of the teeth, and the dentition assumes more and more the character of that of the weasel, while, on the other hand, the peculiarities of the Viverrse disappear ; thus the line Plesictis Stcnoplesictis Pakeoprionodon leads in THE CANUTE, OR DOGS. 275 gentle modifications to Mustela, and henceforth there exist weasels. Equally distinct are the intermediate forms by which is accomplished the transition from the weasel's dentition to that of the Cats. The genus Proteluruz appears likewise with two tuberculate teeth in the upper jaw behind the carnassial tooth. But single species of the genus sometimes show a loss of the back molar, and herein approach the cats ; the back edge of their carnassial tooth, more- over, loses a tubercular heel or process. By this small modification Protelurus has become Pseud- (durus, inasmuch as the modification was general and continued for some length of time. In comparing the following statement of the simplification of the molars of the lower jaw : Premolars Carnassial Tubercular teeth 4 1 l-p 4 m 2 4 1 2> 4 t, 310 p 3 TO, which have actually been observed, and which shows, moreover, that the front premolar jp* has also become reduced it becomes clear that the only distinction between a Pseud&lumis of this kind, for example, Ps. Edivardsii and our present cats, is that it possesses a minute premolar. Hence the great simplification in the number of teeth which Filhol 276 THE MAMMALIA. was able to establish in these animals, justifies the supposition that this small piece will disappear later, in the same manner as has happened previously to the one that existed in front of it (p 1 ), and had previously happened to the tuberculate tooth (??i 2 ). The genus Felis herewith appears upon the scenes. The concentration of the dentition did not re- main stationary at the stage acquired by the cats, O 1 P & w T J the highest degree of specialisation was attained by the so-called Sabre-toothed tiger (Ma- cliairodus) with the dental formula : .31 20 .- 8 , ;.**?! with 26 teeth against 30 in the cats. Machairodus, an animal somewhat the size of a tiger, possessed in its upper jaw a powerful sabre-shaped canine tooth which projected from the mouth downwards extending beyond the lower jaw. This lower jaw shows an indentation obviously produced by the pressure of the huge upper canine teeth as they became more and more developed and endeavoured to make room for themselves. The cause of the dying out of this most definite of all the Carnivora of the period, has been attributed to the extra- THE CANID.E, OR DOGS. 277 ordinary development of these tusks, the length of which finally may have prevented their opening their jaws sufficiently. In answer to this it can only be said that a bad hypothesis is better than none. The sabre-toothed tiger appears and dis- appears ijn the Miocene deposits both of the Old and the New World. Paeudcelurus was shown above to be an inter- mediate form between the weasel and the cat. This does not exclude other intermediate forms. One of these is the ^Elurogale, also the size of a tiger and found in great abundance in the phos- phate of Quercy. Its upper jaw resembles that of Cats, the lower jaw shows the teeth of the Muste- lidae (weasels and otters). The races arrange them- selves in such a manner that, notwithstanding the extraordinary variations in the size of the teeth in those which deviate most from the primary form the lower jaw also has preserved the Cat formula. 1 1 We shall not refrain from pointing out the difficulty which is met with in this apparently simple line of descent. Of all the living Carnivora the Cats possess the most perfect rudimentary clavicles, the others have either smaller traces of these or none at all. All the ancestors of the Cats must at least have possessed clavicles such as are still met with in the Cats. And it is quite intelligible that the clavicles should have con- tinued to exist in Cats, owing to their have retained the habit of 278 THE MAMMALIA. In order to illustrate our remarks we have drawn up the following piece of pedigree : Viverrine dogs (Cynodictis) I Plesictis I Stenoplesictis Proselurus Palseoprionodon I i Pseudielurus WEASELS CATS I Sabre-toothed tiger The above is the shortest way of expressing the result of a long series of the most careful com- parison of facts, and has as much right in claiming to be credited as any other conclusion deduced from scientific investigations, in whatever province the facts have been gathered. When it is admitted that the philologist can arrange the age, connection, and succession of manuscripts, in a tabular form, from the character of the writing, from the use of signs climbing, while in the other animals they would become more and more reduced. Naturally enough we do not know the particulars connected with this reduction. But should we suc- ceed in establishing the want or a greater reduction of the clavicle in one of the branch families in the above pedigree (arranged according to the development of their dentition) our whole arrangement would of course collapse. THE CANID^E, OR DOGS. 279 and word-forms, &c., and that the literary historian may conclude that a certain work was written by a certain author, from the style of the composition and certain modes of expression, &c. ; and further, when it is admitted that a lawyer, by the com- bination of passages, all of which are obscure, can throw light upon a case of Roman law, then I maintain our procedure also a zoologico-palse- ontological method of investigation and drawing conclusions must be granted as a matter of course. The descent of Weasels and Cats from those changing forms of Cynodictis, therefore, presents a great degree of probability but no actual certainty ; for different animals that appear geologically almost as contemporaries, may occur parallel with one another with precisely similar dental formulas and reductions in the jaw. However, we come to the certain conviction that the transformations actually took place, and that our present animal could and must have originated in that natural manner. And as it is mainly our wish merely to pave the way for this opinion, it will be almost superfluous to enter any more fully into the primary and tran- sition forms between the present and the primeval Carnivora. 280 THE MAMMALIA. It may, however, be remarked that our B ars had representatives in the Miocene. In those times there existed the Amphicyon, of the size of a wolf, but in reality a dog with jp 4 , ?n 3 , the broad crowns of the first two molars showing the incomings of tubercles which point to a definite form of food. This characteristic is even more marked in a later form of bear-dog, Hyanarctos (p 3 , m 2 ), and has preserved its full development in the bear (Ursus) from the Pliocene up to the present period. How- ever, the fewer number of teeth of the Hyaenarctos again forbids its being classed with the actual ancestral line of the Bears. The latter with their flat tuberculate molars, which point to a fixed food, and their tolerably blunt carnassials, are compara- tively a late modification, to a certain extent a reversion to the beast of prey. This character has, however, been retained by the polar bear, which has again become a pure flesh- and fish- eater. Gaudry has pointed out an ancestor for Hyaenas in the genus Ictitherium from among the fauna discovered at Pikermi. All that was required in this animal to give its dentition the formula and structure of that of the Hyaena, was the disappear- ance of the second molar above and below (and the THE CANID^E, OR DOGS. 281 Upper one already shows signs of reduction), also an extremely small difference in the carnassial tooth. Indications even existed in the Ictitlierium of the peculiar strength of the premolars of our present hysenas, which show a predilection for gnawing -and crunching bones. Animals of the Viverra type seeui to have been the ancestors of this branch. In the Lower Eocene strata of Europe, but more particularly in the corresponding deposits of North America, numerous Carnivora have been found which differ more from the living families than most of the fossil genera that were brought into connection with them above, and which, moreover, can be brought into this connection, although, taken as a whole, they prove to be but the first stages of very highly developed beasts of prey from the Upper Eocene. The characteristic which most distinctly indicates the low position of the Early Eocene beasts of prey, is the small development of their brain, which is known to us from the form of the skull, and from natural fillings and castings. In their case the olfactory lobes appear as broad pro- cesses of the fore end of the larger division of the brain, the mid-brain being scarcely covered by it, the back part not at all. As regards Europe, the 282 THE MAMMALIA. Arctocyon (Pakeocyon blainville) ' has long since been known as an animal with a brain approaching that of the Marsupial type ; whereas its dentition, which resembles the earlier form of pig-shaped animals, Entelodon, points to the Omnivora, while it has also something of the bear as a flesh-eater. Further, we must mention the Hyanodon and Pterodon, so often referred to, and usually defined as ' mixed forms ' ; they appear somewhat later, it is true, but, nevertheless, show resemblances to the Marsupials for instance, in the form of their teeth they are closely allied to the Thylacinse, though not as regards their change of teeth. With these animals which are partly also found in America Cope classes a whole series of American genera of doubtful position mostly from the Eocene ; he gives them the name of Creodonta, and regards them as the ancestors of the subsequent Carnivora proper. In their case the row of molars is not separated definitely by a carnassial tooth, or but imperfectly so : the jaws are lengthened, and the muscles for chewing are placed in such a man- ner that only a smaller degree of power can be developed than in the subsequent true Carnivora ; 1 Lemoine, 'Eecherches BUT les ossements fossiles deg environs de Reims,' Annales des sciences nat., 1879. THE CANIDJE, OR DOGS. 283 these latter, by the shortening of their jaw and the reduction of their dentition, were all the better able to overpower their prey. One of the most important forms of these Creo- donta because extremely numerous in New Mexico, and found- in three species in the phosphate of Quercy is Oxycena. The species vary in size between a badger and a jaguar. The dental for- mula is : i -, c -, pm -, m -. Herein, therefore, the Eocene fauna of the Old and the New World again show connection. We are the less inclined to enter upon an account of the five families of Creodonta, 1 because the grouping, the assumed connection, and, above all, the derivation of our present large group of Car- nivora, the dogs and cats, often seem to be in want of those safe foundations pointing from case to case, from genus to genus, which Filhol's investi- gations and deductions have made so incontestable. In order, however, to give those of our readers specially interested in the subject some suggestions for further enquiry, we may here mention the 1 Arctocynoidffi, Miacidae, Oxyaenidae, Amblyctonidae, Meso- nychidae. 284 THE MAMMALIA. systematic relationship into which Cope 1 has placed the Creodonta. The mammals from the Wasatch beds of Utah and of New Mexico have been divided into fifty- four species, most of which are distinguished by a very small and evidently low form of brain, to judge from the structure and position of its parts. That of Coryphodon (Fig. 14) appears almost like that of a reptile, and in this character the Hoofed and Clawed Animals agree. They also agree in the structure of their joints, the different parts of their limbs, and also in the number of their toes, of which five were observed in from forty-one to fifty- four species. In the flesh-eaters there is no car- nassial tooth; in the plant- eaters no teeth with crescentic crowns ; all the molars belong to the type of tuberculate teeth, either in primitive sim- plicity, or of that form where the tubercles are compressed to the side, and coalesce into imperfect transverse ridges. On this account the animals have been named Bunotheria, and are arranged in the following manner : Insectivora, Tteniodonta, Tillodonta, Creodonta, Mesodonta Bunotheria. There can be no doubt that these Early Eocene 1 See p. 72, note. THE CANID^, OK DOGS. 285 animals owing to the above-mentioned peculiari- ties show a certain necessity for being classed together, and it is self-evident that they must stand nearer to one another, were it only on account of the smaller period of time since their separation from the primary stock, which must be assumed to have been common to them all. However, in our opinion, the characteristics specified above go no further than to indicate a most general form of con- nection. .When Cope maintains that the different groups of Bunotheria are related to one another, somewhat in the same way as are the orders of Marsupials, it seems to us that this scarcely applies to the case. To give an example : what has Tillo- therium from the Eocene of Wyoming (Fig. 50) in common with the flesh-eaters Arctocyon and Oxytena? By the smallness of its brain most certainly nothing ; nor by its five toes, and the cir- cumstance that the whole sole of the foot is applied to the ground. The resemblances in the molars are not remarkable, while the decidedly rodent-like form of the incisors only proves the peculiarity of the animal. Any typical feature such as the marsupial pouch or the marsupial bones, or the openings of the urinary and genital organs peculiar to the Mar- supials is not met with in any of these animals, 286 THE MAMMALIA. as far as can be judged from the often great paucity of their remains. Only one point stands out in this attempt to throw light upon the relationships between the FIG. 50. - Skull of Tillotherium fodiens, from above. One-fourth nat. size. After Marsh. mammals of that early period ; the indrawing of the Insectiv&ra, of that type which has been pretty faithfully preserved from the earliest traces of THE SEALS. 287 Marsupials or Insectivora in the Trias down to the present day, and which seems to have gradually sent out off-shoots in the most different directions, till at length they became unrecognisable. 9. THE SEALS. According to the form of their skull, dentition, and mode of life, Seals are 'carnivorous animals that have adapted themselves to a life in water,' and in this way they are generally described. In order to make the theory acceptable, it is customary to point to our Sea-otter, which, unlike its nearest relative that thirsts for warm blood, has become a pure fish-eater. The Sea-otter uses its hind limbs after the manner of seals, and its skull shows a depression of a similar kind to that which has proved advantageous to the Seals. Hence, so it is said, we have to imagine the ancestors of the Seals on that line which has led them farther and farther from their original forms, which very gra- dually changed their limbs into fin- shaped rudders (while perfectly retaining the pelvis and the articu- lation of the skeleton), and whose skull became a light, thin-walled box not burdened with strong teeth. Only the Walrus (Trichechus) has developed a couple of heavy tusks, corresponding with its 288 THE MAMMALIA. entirely different mode of life, inasmuch as it burrows in the ground for certain kinds of mussels. All the others hunt for fish, which they can readily tear to pieces with their sharp canine teeth and pointed molars, which are compressed somewhat to the side. Of fossils that might illustrate the gradual in- coming of Seals there are none. We conclude that the process must, at one time, have begun with carnivorous land-animals. The idea that the re- verse might have been the case by their having, as sea-animals, taken to a life on land, has as little value here as in the case of the Cetaceans, which are mammals, and have never been anything else. The period during which they changed their element lies at an immeasurable distance in the far past, but is probably less distant than that in which the ancestors of the whales took to the sea while re- ducing their hind limbs. There can be no question about making the Whales (of course only the toothed group) the primary parents of the Seals. If any comparison of the kind is thought of, the Eocene Zeuglodonta could alone be taken into consideration. But even these latter do not show any points of connection; their skull would have to be retro-metamorphosed to form THE SEALS. 289 the skull of the seal, and their dentition would have to be fuller ; hence the supposed points of connec- tion would be confined to a superficial resemblance in the crowns of the molars, as there was very probably an essential difference in the formation of the hind limbs. As we are absolutely without any clue to the origin of Seals, we may here mention one other circumstance which seems to speak in favour of the great age of this side-branch of the primary Carnivora. What we yet know of the change of teeth in Seals shows that the change takes place at an extraordinarily early stage of life. 1 In most cases the change takes place before birth ; the milk- teeth never come to be of any use whatever, and the permanent teeth are cut when the young animal is but a few weeks old, and while making its first feeble efforts to join its parents in their repasts. Fig. 51 shows the teeth of a probably still unborn Greenland seal (Phoca grunlandica). The shading shows the limit of the gums. It will be seen that the milk-teeth have already vanished, all but a few unimportant remains; d ?- have wholly 1 J. Steenstrup, ' Maelkestandsaettet hos Remmesaelen,' Naturhistorick Foreningens Vidensk. Meddeleser. 1880. U 290 THE MAMMALIA. disappeared, the first and only permanent molar of the lower jaw has already cut the gum. Teeth of the same kind as these milk-teeth, which are wholly without any significance to the individual as functional organs, but of the highest interest for the history of the group, we became acquainted with when discussing the Whales (p. 247). FIG. 51.- Foetal Teeth of a Greenland Seal. The embryonal teeth of the Whalebone whales even though there were no Dolphins or Sperm whales are an irrefutable proof that the Whalebone whales are descended from toothed animals. In the same way the case before us shows, that the milk-teeth of Seals which have in our day become of utter THE SEALS. 291 insignificance to the organism, were of actual service to their ancestors, just as the deciduous teeth of most of our present mammals are of use for several years. None of these milk-teeth have the prospect of being preserved like the one remaining deciduous tooth of the Marsupials (p. 94) ; accord- ingly the Seals of future periods will undoubtedly not show a trace of milk-teeth. The Seals belong to the physically weaker groups of mammals, and it is certainly most remarkable, and as yet not explicable, that the other mammals also, which have already been discussed, and are allied to the Seals as regards the suppression of the change of teeth, belong, on the whole, to the less favoured or less strongly developed orders. For, as we have repeatedly remarked, the main feature that runs through the whole world of mammals is the concentration of strength upon a shortened jaw, at the cost of the disappearance of teeth. This is most evident in the case of true Carnivora, where, however, the milk-teeth still play an important part. 10. THE INSECTIVORA, OK INSECT-EATERS. RODENTIA, OR RODENTS. CHEIROPTERA, OR BATS. Of these three orders the Insect-eaters have already been mentioned from time to time. They c 2 292 THE MAMMALIA. existed in very early times, and had, at the begin- ning of the Tertiary, already attained a stage of development which has been transmitted to the present members of the group, with but trifling modifications; and it is probable that a transi- tion into hoofed and carnivorous animals had shown signs of incoming as early as the so-called Mesozoic period. The question as to why all the group did not join in the transformation is as obvious as the answer to all similar questions : that the special conditions of life for these animals must have existed uninterruptedly, and that, in addition, they possessed a great amount of adap- tability. Thus we find the order of Insect-eaters which is represented in Central Europe only by the hedgehog, mole, and shrew, but more numer- ously in other parts in many ways similarly adapted to the most varied conditions of existence as the Eodents. In fact, their variability, even in primeval times, explains the fact of their having been able to adapt themselves to entirely new organisations, and Huxley specially traces to them the hoofed and carnivorous animals. The same remarks apply to the Rodents, except that in all of the periods known to us through fossils, they were far more numerously represented. INSECT-EATERS, RODENTS, AND BATS. 293 The Rodent type is likewise found perfected at the beginning of the Tertiary period. It may be said that it was then less specialised, that most of the Eodents of those days were more carnivorous than the majority of our day, or, at least, more omni- vorous ; however, little is to be gained from this for our present enquiry. The dentition of the Eodents appears to be prepared, and almost perfectly attained, by the Marsupials ; l and thus in following their tracks we are again referred to the Jura period, and even further back, where the separation of an already developed mammalian fauna had taken place : into Marsupials (as the main group), Eodents, and Insect-eaters. The latter order, no doubt, gave rise to the Bats, which have fluttered about in their present shape since the Eocene period. Two of our most common 1 A comparison of the very different shapes of the molars in the Rodents among one another, and the approximation of many of the genera not as yet decided Rodents to the Rodent type (for instance, the wombat, the fingered-animal, and rock coney) renders it extremely probable that even our present Rodents are not of one and the same origin. * The fact remains, animals of different derivation have attained a similar exterior, succeed extremely well in the struggle for existence, or even better in their endeavour to obtain food. Unlike as they may be, in one point they are incontestably alike, Le. in the development of continuously growing incisors.' BAUME. 294 THE MAMMALIA. genera, Vespertilio and Ehinolophus, were contem- poraries of the Palasotheridse and the Cynodictis of South-western France. As regards their origin we can only confess our ignorance on the subject, even though we can perfectly well imagine the transfor- mation of a climbing insect-eater into a flying one. The elongation of the fingers of the fore limb, and the expansion of the flying membrane to the hind limbs, took place in those early periods from which, as far as our knowledge of the Mammalia is con- cerned, only a few dim rays of light have found their way to us. 11. THE PROSIMOB, SEMI- APES. SIMIffi, APES. THE MAN OF THE FUTURE. The opinion of zoologists of the Linnsean school, and those belonging to the first half of our century, that the whole class of Semi-apes were, in fact, half apes has generally been abandoned; the opinion was based upon the occurrence of hands on the fore and hind limbs, upon the formation of the face, and upon the peculiar dentition, which in most cases shows no gaps. The more recent theory does not ex- clude the supposition that among the very differently formed genera of so-called Semi-apes, one or other species might claim a closer relationship with the SEMI-APES AND APES. 295 Apes, but neither the result of any anatomical or palaeontological investigation allows us to draw even a plausible inference of any such probability. As there are only a small number of genera of Semi-apes, and these are confined to Madagascar (Africa an m o> wnile tne intellectually higher races 4 O will be distinguished by the dental formulas : 1 1 2 3 y ' j, P and i * c \, V\,m\ THE MAN OF THE FUTURE. 301 We agree with this in so far that, as a rule, the reduction of the dentition where the disappearance does not affect the whole set of teeth can be brought into connection with the idea of progress, and many proofs of this have been given in the course of our discussion. Still this higher faculty of resistance and of acquiring food is not necessarily accom- panied by an increase in the power of the adapta- bility and a perfecting of the intellectual faculties. In the Cat we have a more powerful, and hence a higher development of the nature of the rapacious animal than in the Dog, with its more old-fashioned form of dentition. Yet who would think of placing Cats as intellectually higher than Dogs ? It is the same with the prospects of the human races. Modifications in the human dentition are sure to take place, as surely as man cannot rid himself of his animal ancestors, even though they may be felt to be inconvenient. But progress in the intellectual and moral domain and here our well-founded idealism steps in is not dependent upon the possession or the loss of our wisdom teeth. The correlation is not wanting, but it makes itself felt in an opposite direction. The man who is engaged in making inventions and in scientific pursuits, and is advancing and encouraging all the nobler and 302 THE MAMMALIA. more refined enjoyments of life, is not improving the instruments for the acquisition of his food ; they deteriorate in his hands a condition which first began to make its appearance with the inven- tion of cooking. The reduction of the human dentition which has been of advantage to the species in its struggle for existence has further increased and changed to a kind of atavism or reversion, since reason, acquired with speech, has made Man more and more independent of the direct effects of his natural surroundings. Hence it is not merely from a purely zoological point of view that an inference is formed regarding the future change of the human race. Moreover, we cherish the hope which is justified by scientific experiences and the belief, which rests upon the same foundation, and these convince us of the sure advance of humanity, and of the gradual and general diffusion of morality, culture, and well- being among the various races of Man. INDEX. ACK ACERATHERIUM, 81, 190, 195 Adapis, 295 YElurogale, 277 Amblyctonidse, 283 Amphibos, 178 Amynodon, 1 Anchitherium, 79, 190, 203, 210 Ancodus, 170 Ancylotherium, 126 Animals, Crescent-toothed, 137 Odd-hoofed, 189 Ohio, 233 Pair-hoofed, 137 Anoa, 179 Anoplotherium, 80, 129 Ant-bears, 124 Antelope arabica, 176 Antelopes, 79, 173 Saiga, 76 Anthracotherium, 80, 142 Anthropomorphae, 297 Antilocapra, 161 Appenzell, cattle of, 179 Arctocyon, 80, 282, 285 Arctocyonidffi, 283 Arno, Val d' (Pliocene), 79 Auchenia, 157 CAT BABIRUSSA, 138 Balama, 250 Baltavar (Upper Miocene), 79 Bear, 280 Bearded Whale, 247 Bear-dog, 280 Bern cattle, 179 Bettongia, 100 Bibos, 178 Bibovina, 178 Bison, 178, 179, 187 Boar, wild, 138 Bos, 176, 178 Bradypus, 114 Bramatherium, 172 Brontotherium, 81, 199 Bronze-dog, 264 Bubalina, 178 Buffalo, 186 Buffelus, 178 Bull-dog, 264 Bunodonta, 137 Bunotheria, 284 CADICONA Lignite (Lower Mio- cene), 79 Cainotherium, 79, 182 304 INDEX CAM DtTC Camargue, house of, 221 Camels, 154 Creodonta, 282, 283, 284 Crescentic-toothed animals, Camelus, 157 137 Canidac, 259 Ctenacodon, 100, Canis, 259 Cynodictis, 271 antarcticus, 262 Cyon, 266 anthus, 262 argentatus, 262 DASYPUS, 120 azarse, 262, 268 Dasyurus, 269 cancrivorus, 262 Debruge, Lignite (Upper fulvus, 262 Eocene), 79 latrans, 262 Deer, 79 littoralis, 262 Bed, 162 lupaster, 264 Rein, 165 lupus, 264 Telemetacarpal, 163 magellanicus, 262 Diceratherium, 81 pallipes, 264 Dichobune, 80 suessi, 265 Dicotyles, 138, 141 vulpes, 260 Dicrocerus, 79, 161 zerda, 262 Didelphia, 9b Cattle of Appenzell, 179 Didelphys, 97, 99 173, 178 Diluvial Horse, 224 Dutch, 179 Dingo, 262 of Bern, 179 Dinoceras, 81, 241 Short-headed, 189 Dinocerata, 240 Tyrolese, 189 Dinotherium, 79, 236 Cats, 275 Diphyodonta, 43 Cave Wolf, 265 Diplopus, 170 Central German Horse, 224 Diprotodon, 103, 104 Cervulus, 161 Diptacodon, 81 Cervus canadensis, 163 Dogs, races of, 259 Cetotherium, 251 Bear- dog, 280 Chalicotherium, 201 Bronze-dog, 264 Chelys fimbriata, 37 Bull-dog, 264 Chlamydophorus, 120 Viverrine dog, 271 Chceropotamus, 142 wild dogs of Africa, 264 Chcerotherium, 142 Dolphins, 248 Cholcepus, 149 Dorcatherium, 79 Colonoceras, 81 Dremotherium, 79 Coryphodon, 80, 81, 132, 284 Duck Mole, 86 INDEX 305 Dutch cattle,179 Dwarf musk deer, 167 ECHIDNA, 86 Egerkingen (Middle Eocene), 80 Eibiswald (Middle Miocene), 79 Elasmotherium, 190, 197 Elephants, 79, 228, 235 Elk, 165 Entelodon, 80, 282 Eohippus, 81, 190, 213 Eohyus, 143 Eppelsheim (Upper Miocene), 79 Equus caballus, 218 stenonis, 216 Eutheria, 93 FELIS, 276 Fingered animal, 293 Fontainebleau, sand (of the Lower Miocene), 79 Fox, 260 Frontosus race, 179 GELOCUS, 79, 164, 170 Georgsmiinde (Middle Eocene), 79 Gerard-le-Puy, St. (Lower Mio- cene), 79 Giraffe, 170 Girdled animals, 120 Glossotherium, 124 Glyptodon, 123, 124 Greenland seal, 290 Giinzberg (Middle Eocene), 79 HALICORE, 242 Halitherium, 242 Hampshire (Upper Eocene), 79 Hatteria, 28 Helaletes, 81, 193 Helladotherium, 79, 172 Helohyus, 143 Hipparion, 79, 190, 203 Hippopotamus, 144, 145, 146, 203 Hog-deer, 138 wart, 138 Hollow-horned animals, 173 Horse, 190, 201 Diluvial, 224 occidental, 223 of the Camargue, 221 of Solutre, 220 oriental races of, 223 wolf-toothed, 210 Hysemoschus, 167, 168 Hyama, 79, 280 Hyasnarctos, 280 Hysenodon, 80, 282 Hydaspitherium, 172 Hydropotes, 163 Hyopotamus, 168 Hyrachyus, 81, 193 Hyracodon, 81 Hyracotherium, 80 Hyrax, 241 ICTICYON, 266 Ictitherium, 79, 280 Insectivora, 284, 286 JACKAL, 264 Jerboa, 76 306 INDEX XAP LA FERE, Sandstein (Lower PHA Eocene), 80 N ECKOLEMUE, 295 Lama, 155 Ne oplagi au i ax . inn Leberon (U Pper Miocene), Norwich crag, 79 Nototherium, 104 Leptobos, 178 Lignite of Cassino (Pliocene), London clay (Lower Eocene), Odd-hoofed animals, 189 Lophiodon, 190, 192 Oemgen (Upper Miocene) Ohio animals, 233 Oreodon, 81 n.al MS of , he ho MACHAIRODUS, 276 Macrauchima, 228 Macrotherium, 125 3r/ d ' igs, 70, 137, 141 Saiga antelope, 76 'ikermi (Upper Miocene), 79 Sand of Orleans (Middle Eo- 'lagiaulax, i>9, 100 cene), 79 E lesictis, 274 Sansan (Middle Miocene), 79 I lesiometacarpal deer, 163 Selenodonta, 137 'liauchenia, 157 Short-headed cattle, 189 I Pliohippus, 81, 190, 215 Shorthorn bull, 175 ) Pliolophus, 80 Simocyon, 79 i Poebrotherium, 159 Sivalik hills (Upper Miocene), } Poodle, 264 79 1 'ortacina, 178 Sivatherium, 172 ] Mmigenius bos, 179 Sloth, giant, 113 Proffilurus, 275 Smooth whale, 250 'Probubalus, 178, 179 Soissonnais, lignite of (Lower' Procamelus, 156 Eocene), 80 Procervulus, 160 Solutre, horses of, 220 Prorastomus, 244 Squalodon, 251 Protohippus, 81, 190, 214 Stegodon, 234 Protolabos, 156 Stenoplesictis, 274 Prototheria, 93 Strata, tertiary, of N. America, Prox, 160 81 Pseudselurus, 275 Pterodon, 80, 282 T.ENIODONTA, 284 Tapir, 79, 189, 190 QUERCY PHOSPHORITE (Upper Tapiravus, 81, 193 Eocene), 79 Taurina, 178 Telemetacarpal deer, 163 Tertiary strata of N. America, RED DEER, 162 81 Rein deer, 165 Thylacinus, 269 Rhinoceros, 79, 81, 190, 194 Thylacoleo, 102 minutus, 198 Tillodonta, 284 Rhinolophus, 294 Tillotherium, 81, 286 Rhytina, 243 Tinohyus, 143 River horse, 144 Toothed whales, 247 Ronzon, lime rocks of (Lower Tragulid, 167 , Miocene), 79 Trichechus, 287 Ruminants, 150 Tyrolese cattle, 189 308 UROJIASTIX, 28 Ursus, 280 VRO -- u ARNO peg, Vespertilio, 294 Vienna basin, 79 Viverra;, 274 viverrine dog, 271 WALROS, 287 Wapiti, 163 Wart-hog, 138 Wh ales, toothed, 247 bearded, 247 7 INDEX ZETT Wild boar, 138 - Indian, 264 Wolf-tooth of horse, 210 Wombat, 104, 293 XlPHODON, 182 Xiphodontherium, 182 , 179 251 I IV! 000720359 9 ^2 CAUFOS^