Part 7

So at last, group by group, we have gone through the ungulates, and the bisons alone are left, and as the American animal has short, incurved horns, set low down on the skull and far apart at the base; premaxillaries falling short of the nasals; the last cervical and the anterior dorsal vertebrae with spines; fourteen pairs of ribs, and a mane covering the shoulders, we conclude that it is a bison, and as the same characteristics with minor variations are shown by the European species, often, but wrongly, called "aurochs," we say that these two alone of existing Bovidae are bisons, with the yak as a somewhat questionable relative.

In all essential respects the two bisons are very similar, but minute comparison shows that the European species, Bison bonasus, has a wider and flatter forehead, bearing longer and more slender horns, and all the other distinctive features are less pronounced. In the American species, Bison bison, the pelvis is less elevated, producing the characteristic slope of the hindquarters. It is a coincidence that the two regions originally inhabited by the bisons are those in which the white races of men have to the greatest extent thrown their restless energies into the struggle for existence, with the result that extinction to nearly the same degree has overtaken these two near cousins among oxen. A few wild members of the European species still exist in the Caucasus, as a few of the American are left in British America, but elsewhere both exist only under protection.

The carefully kept statistics of the Bielowitza herd in Grodno, western Russia, which includes nearly all but the few wild ones, shows that between 1833 and 1857 they increased in number from 768 to 1,898, but from this maximum the decrease has been constant, with trifling halts, until in 1892 less than five hundred were left; so that even if the Peace River bison are counted with the remnant of the American species, it is probable that the survivors of each race are about equal in number.

It is true that the number of our own species has lately been placed as high as a thousand, but even if these figures are correct, the seeds of decay from internal causes, such as inbreeding and the degeneration of restraint, are already sown, and the inevitable end of the race is not far off.

The Peace River, or woodland, bison has lately been separated as a sub-species (B. bison athabascae), distinguished from the southern and better known form by superior size, a wider forehead, longer, more slender and incurved horns, and by a thicker and softer coat, which is also darker in color. Now, it is an interesting fact that a fossil bison skull from the lower Pliocene of India resembles the present European species, and in later geological times very similar bisons closely allied to each other, if not identical, inhabited all northern regions, including America. These were large animals with wide skulls, and there is little doubt that from this circumpolar form came both of the bisons now inhabiting Europe and America. Out of some half dozen fossil bison which have been described from America, none earlier than the latest Tertiary, Bison latifrons from the Pleistocene seems likely to have been the immediate ancestor of recent American species, and as the one skull of the woodland bison which has been examined resembles both latifrons and the European species more than the plains species does, it seems probable that these two more nearly represent the primitive bison, of which the former inhabitant of the prairies is a more modified descendant.

The process of elimination has at last led to this outline definition of a bison, but among the ungulates we have passed over, there are certain others which concern us because they are American.

Sheep and goats agree together and differ from oxen in being usually of smaller size; the tail is shorter, the horns of females are much smaller than those of males, they lack the accessory column on the inner side of the upper molars, and the cannon bone is longer and more slender; but when it comes to a comparison of the one with the other, it is by no means always easy to tell the difference. It is true that the early Greeks seem to have had a rough and ready rule under which mistakes were not easy, for Aristotle tells us "Alcmaeon is mistaken when he says that goats breathe through their ears," but the severely practical methods of our own day leave us little but some very minute points of difference. One of the best of these lies in the shape of the basi-occipital bone, but naturally this can be observed only in the prepared skull. The terms often employed to denote difference in the horns can have only a general application, for they break down in certain species in which the two groups approach each other. The following table expresses some fairly definite points of separation:

SHEEP (Ovis). GOAT (Capra).

1. Muzzle hairy except between 1. Muzzle entirely hairy. and just above the nostrils.

2. Interdigital glands on all 2. Interdigital glands, when the feet. present, only on fore feet.

3. Suborbital gland and pit 3. Suborbital gland and pit usually present. never present.

4. No beard nor caprine 4. Male with a beard and smell in male. caprine smell.

5. Horns with coarse transverse 5. Horns with fine transverse wrinkles; yellowish striations, or bold knobs or brown; sub-triangular in front; blackish; in male in male, spreading outward more compressed or angular, and forward with a sweeping backward circular sweep, points with a scythe-like curve or turned outward and forward spirally, points turned upward and backward.

These features are distinctive as between most sheep and most goats, but the Barbary wild sheep (Ovis tragelaphus) has no suborbital gland or pit, a goat-like peculiarity which it shares with the Himalayan bharal (Ovis nahura), in which the horns resemble closely those of a goat from the eastern Caucasus called tur (Capra cylindricornis), which for its part has the horns somewhat sheep-like and a very small beard. This same bharal has the goat-like habit of raising itself upon its hind legs before butting.

Both groups are a comparatively late development of the bovine stock, as they do not certainly appear before the upper Pliocene of Europe and Asia, and even at a later date their remains are not plentiful. Goats appear to have been rather the earlier, but are entirely absent from America.

The number of distinct species of sheep in our fauna is a matter of too much uncertainty to be treated with any sort of authority at this time. Most of us grew up in the belief that there was but one, the well-known mountain sheep (Ovis canadensis), but seven new species and sub-species have been produced from the systematic mill within recent years, six of them since 1897. It is no part of the purpose of the present paper to dwell upon much vexed questions of specific distinctness, and it will only be pointed out here that the ultimate validity of most of these supposed forms will depend chiefly upon the exactness of the conception of species which will replace among zoologists the vague ideas of the present time. Whatever the conclusion may be, it seems probable that some degree of distinction will be accorded to, at least, one or two Alaskan forms.

As sheep probably came into America from Asia during the Pleistocene, at a time when Bering's Strait was closed by land, it might be expected that those now found here would show relationship to the Kamtschatkan species (Ovis nivicola); and such is indeed the case, while furthermore, in the small size of the suborbital gland and pit, and in comparative smoothness of the horns, both species approach the bharal of Thibet and India, which in these respects is goat-like.

When one considers the poverty of the new world in bovine ruminants, it seems strange that three such anomalous forms should have fallen to its share as the prong-horn, the white goat and the musk-ox, of none of which have we the complete history; two of the number being entirely isolated species, sometimes regarded as the types of separate families.

The prong-horn is a curious compound. It resembles sheep in the minute structure of its hair, in its hairy muzzle, and in having interdigital glands on all its feet. Like goats, it has no sub-orbital gland nor distinct pit. Like the chamois, it has a gland below and behind the ear, the secretion of which has a caprine odor. It has also glands on the rump. It is like the giraffe in total absence of the accessory hoofs, even to the metapodials which support them. It differs from all hollow horned ungulates in having deciduous horns with a fork or anterior branch. There is not the least similarity, however, between these horns and the bony deciduous antlers of deer, for, like those of all bovines, they are composed of agglutinated hairs, set on a bony core projecting from the frontal region of the skull.

It is well known that these horn sheaths are at times shed and reproduced, but the exact regularity with which the process takes place is by no means certain, although such direct evidence as there is goes to prove that it occurs annually in the autumn. Prong-bucks have shed on eight occasions in the Zoological Gardens at Philadelphia, five times by the same animal, which reached the gardens in October, 1899, and has shed each year early in November, the last time on October 22, 1903, and the writer has seen one fine head killed about November 5 in a wild state, on which the horn-sheaths were loose and ready to drop off.

But few of these delicate animals have lived long enough in captivity to permit study of the same individual through a course of years, and the scarcity of observations made upon them in a wild state is remarkable. That irregularity in the process would not be without analogy, is shown by the case of the Indian sambur deer, of which there is evidence from such authority as that king of sportsmen, Sir Samuel Baker, and others, that the shedding does not always occur at the same season, nor is it always annual in the same buck; and by Pore David's deer, which has been known to shed twice in one year.

When resemblances such as those of the prong-horn are so promiscuously distributed, the task of fixing their values in estimating affinities is not a light one, and in fact the most rational conclusion which we may draw from them is that they point back to a distant and generalized ancestor, who possessed them all, but that in the distribution of his physical estate, so to speak, these heirlooms have not come down alike to all descendants. There is again a complicating possibility that some may be no more than adaptive or analogous characters, similarly produced under like conditions of life, but quite independent of a common origin, and it is seldom that we know enough of the history of development of any species to conclude with certainty whether or not this has been the case. At all events, the prong-buck is quite alone in the world at present, and we know no fossils which unmistakably point to it, although it has been supposed that some of the later Miocene species of Cosoryx--small deer-like animals with non-deciduous horns, probably covered with hair, and molars of somewhat bovine type--may have been ancestral to it, but this is little more than a speculation. What is certain is that Antilocapra is now a completely isolated form, fully entitled to rank as a family all by itself.

In the musk-ox (Ovibos moschatus), or "sheep-ox," as the generic name given by Blainville has it, we meet with another strange and lonely form which has contributed its full share to the problems of systematic zoology. Its remote and inaccessible range has greatly retarded knowledge of its structure, and it is only within the last three years that acquaintance has been made with its soft anatomy, and at the same time with a maze of resemblances and differences toward other ruminants, that perhaps more than equals the irregularities of the prong-buck. But unlike that species, there is in the musk-ox no extreme modification, such as a deciduous horn, to separate it distinctly from the rest of the family. A recapitulation of these differences would be too minutely technical for insertion here, and it must be enough to say that while it cannot be assigned to either group, yet in the distribution of hair on the muzzle, in the presence of a small suborbital gland, in shortness of tail and the light color of its horns, it is sheep-like; in the absence of interdigital glands, the shortness and stoutness of its cannon bones, and in the presence of a small accessory inner column on the upper molars, it is bovine. But in the coarse longitudinal striation of the bases of its horns it differs from both. The shape of the horns is also peculiar. Curving outward, downward and then sharply upward, with broad, flattened bases meeting in the middle line, their outlines are not unlike those of old bulls of the African buffalo.

At the present time the musk-ox inhabits only arctic America, from Greenland westward nearly to the Mackenzie River, but its range was formerly circumpolar, and in Pleistocene times it inhabited Europe as far south as Germany and France. The musk-ox of Greenland has lately been set aside as a distinct species. The most we can say is that Ovibos is a unique form, standing perhaps somewhere between oxen and sheep, and descended from an ancient ruminant type through an ancestry of which we know nothing, for the only fossil remains which are at all distinguishable from the existing genus, are yet closely similar to it, and are no older than the Pleistocene of the central United States; in earlier periods its history is a blank about which it is useless to speculate.

The last of our three anomalies, the white, or mountain goat (Oreamnos montanus), is not as completely orphaned as the other two, for it seems quite surely to be connected with a small and peculiar series consisting of the European chamois and several species of Nemorhaedus inhabiting eastern Asia and Sumatra. These are often called mountain antelopes, or goat antelopes. So little is yet known of the soft anatomy of the white goat that we are much in the dark as to its minute resemblances, but its glandular system is certainly suggestive of the chamois, and many of its attitudes are strikingly similar. In all the points in which it approaches goats it is like some, at least, among antelopes, while in the elongated spines of the anterior dorsal vertebrae, which support the hump, and in extreme shortness of the cannon bone, it is far from goat-like. The goat idea, indeed, has little more foundation than the suggestive resemblance of the profile with its caprine beard. It is truly no goat at all, and should more properly be regarded as an aberrant antelope, if anything could be justly termed "aberrant" in an aggregation of animals, hardly any two of which agree in all respects of structure. No American fossils seem to point to Oreamnos, and as Nemorhaedus extends to Japan and eastern Siberia, it is probable that it was an Asiatic immigrant, not earlier than the Pleistocene.

From this intricate genealogical tangle one turns with relief to the deer family, where the course of development lies reasonably plain. If the rank of animals in the aristocracy of nature were to be fixed by the remoteness of the period to which we know their ancestors, the deer would out-rank their bovine cousins by a full half of the Miocene period, and the study of fossils onward from this early beginning presents few clearer lines of evidence supporting modern theories respecting the development of species, than is shown in the increasing size and complexity of the antlers in succeeding geological ages, from the simple fork of the middle Miocene to those with three prongs of the late Miocene, the four-pronged of the Pliocene, and finally to the many-branched shapes of the Pleistocene and the present age. Now it is further true that each one of these types is represented today in the mature antlers of existing deer, from the small South American species with a simple spike, up to the wapiti and red deer carrying six or eight points, and still more significant is it that the whole story is recapitulated in the growth of each individual of the higher races. The earliest cervine animals known seem to have had no antlers at all, a stage to which the fawn of the year corresponds; the subsequent normal addition in the life-history, of a tine for each year of growth until the mature antler is reached, answering with exactness to the stages of advance shown in the development-history of the race. A year of individual life is the symbol of a geological period of progression. This is a marvelous record, of which we may say--paraphrasing with Huxley the well-known saying of Voltaire--"if it had not already existed, evolution must have been invented to explain."

The least technical, and for the present purpose the most useful of the characters distinguishing existing deer from all of the bovine stock, lies in the antlers, which are solid, of bony substance, and are annually shed. They are present in the males of all species except the Chinese water deer, and the very divergent musk-deer, which probably should not be regarded as a deer at all. They are normally absent from all females except those of the genus Rangifer. Most deer have canine teeth in the upper jaw, though they are absent in the moose, in the distinctively American type and a few others. The cleaned skull always shows a large vacuity in the outer wall in front of the orbit, which prevents the lachrymal bone from reaching the nasals. No deer has a gall bladder. There are many other distinctions, but as all have exceptions they are of value only in combinations.

The earliest known deer, belonging to the genus Dremotherium, or Amphitragulus, from the middle Tertiary of France, were of small size and had four toes, canine teeth and no antlers. Their successors seem to have borne simple forked antlers or horns, probably covered with hair, and permanently fixed on the skull. Very similar animals existed in contemporaneous and later deposits in North America. From this point the course of progress is tolerably clear as to deer in general, although we are not sure of all the intermediate details--for it must not be forgotten that a series of types exhibiting progressive modifications in each succeeding geological period is quite as conclusive in pointing out the genealogy of an existing group as if we knew each individual term in the ancestral series of each of its members. Thus we do not yet know whether the peculiar antler of the distinctively American deer, of the genus Mazama, is derived from an American source or took its origin in the old world, for the fossil antlers known as Anoglochis, from the Pliocene of Europe, are quite suggestive of the Mazama style, but as nothing is known of the other skeletal details of Anoglochis, any such connection must at present be purely speculative, but the element of doubt in this special case in no way disturbs the certainty of the general conclusion that all our present Cérvidae have come through distinct stages in the successive periods, from the simple types of the middle Tertiary.