antelopes, sheep and goats agree in having hollow horns of material similar to that of which hair and nails are formed, permanently fixed upon the skull in all but one species; none of them have more than the two middle digits functionally developed, one on each side of the axis of the leg; none have the lower ends remaining of the meta-podial bones belonging to the two accessory digits; and none have either incisor or canine teeth in the upper jaw.
From animals so constructed we may first take out goats and sheep, in which the female horns are much smaller than those of males, and in some species are even absent. In nearly all of them the horns are noticeably compressed in section, either triangular or sub-triangular near the base, and are directed sometimes outwardly from the head with a circular sweep; at others with a backward curve, often spirally. The muzzle is always hairy; there is no small accessory column on the inner side of the upper molars, found always in oxen and in some antelopes; the tail is short, and scent glands are present between the digits of some or all the feet.
Now, as to the perplexing animals popularly known as antelopes. No definition could be framed which would include them all in one group, for every subordinate character seems to be present in some and absent in others, so that the most that can be done with this vast assemblage is to arrange its contents in series of genera, which may or may not be called sub-families, but which probably correspond in some degree to their real affinities. We can only say of any one of them that it is an antelope because it is not a sheep, nor a goat, nor an ox. They concern us here only to be eliminated, for they are not American, our prong-buck having a sub-family all to itself, as we shall see later, and the so-called "white goat" being usually regarded as neither goat nor truly antelope.
Within the limits of the real bovine animals, four quite distinct types may be made out, chiefly by the position of the horns upon the skull and by the shape of the horns themselves. There are also differences in the relations of the nasal and premaxillary bones, the development of the neural spines of the vertebrae, and the hairy covering of the body.
In the genus Bos the horns are placed high up on the vertex of the skull, which forms a marked transverse ridge from which the hinder portion falls sharply away. The horns are nearly circular in section and almost smooth; usually they curve outward, then upward and often inward at the tip; the premaxillaries are long and generally reach to the nasals, and the anterior dorsal vertebrae are without sharply elongated spines, so that the line of the back is nearly straight. These, the true oxen, as they are sometimes termed, now exist only in domesticated breeds of cattle.
In the gaur oxen (Bibos) the horns are situated as in Bos, high up on the vertex, but are more elliptical in section; the premaxillaries are short; the dorsal vertebrae, from the third to the eleventh, bear elongated spines which produce a hump reaching nearly to the middle of the back; the tail is shorter, and the hair is short all over the body. The three species—gaur, gayal and banteng—inhabit Indo-Malayan countries, and all of them are dark brown with white stockings.
The buffaloes (Bubalus) are large and clumsy animals with horns more or less compressed or flattened at their bases, set low down on the vertex, which does not show the high transverse ridge of true oxen and gaurs. In old bulls of the African species the horns meet at their base and completely cover the forehead. In the arni of India they are enormously long. The dorsal spines are not much elongated, and there is no distinct hump; the premaxillae are long enough to reach the nasals. Hair is scanty all over the body, and old animals are almost wholly bare. The small and interesting anoa of Celebes, and the tamarao of Mindoro, are nearly related in all important respects to the Indian buffalo, and the carabao, used for draught and burden in the Philippines, belongs to a long domesticated race of the same animal.
Finally, in the genus Bison the horns are below the vertex as in buffaloes, but are set far apart at the base, which is cylindrical; they are short and their curve is forward, upward and inward; the anterior dorsal and the last cervical vertebrae have long spines which bear a distinct hump on the shoulders; the premaxillae are short and never reach the nasals; there are fourteen, or occasionally fifteen, pairs of ribs, all other oxen having but thirteen, and there is a heavy mane about the neck and shoulders. The yak of central Asia is very bison-like in some respects, but in others departs in the direction of oxen.
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
