Sir Harry Johnston has quite recently made known another genus of Giraffidae living in the Semliki forest, Belgian Congo district. The skin and two skulls, as well as the bones of the feet, are known from specimens sent by Sir Harry Johnston to the Natural History Museum, and briefly described to the Zoological Society by Professor Ray Lankester.[[199]] This creature, of which the native name is "Okapi," is proposed to be called Ocapia johnstoni. The first actual specimens which reached this country were two bandoliers made from the skin of the flanks, which were striped black and white, and were not unnaturally held to be portions of the skin of a new species of Zebra. The animal is of about the size of a Sable Antelope, and the back and sides are of a rich brown colour; it is only the fore- and hind-limbs which are striped, the striping being longitudinal, i.e. parallel with the long axis of the body. The head is Giraffe-like, but there are no external horns; wisps of curled hairs seem to represent the vestiges of the horns of other Giraffes. The tail is rather short, and the neck is rather thick and short. The skull is clearly Giraffine. The basicranial axis is straight, and the fontanelle in the lachrymal region is very large. Upon the frontal bones near their parietal border is a large boss on either side, which presumably represents the horn core or "os cornu." On the mandible the great length of the diastema between the incisors and premolars is a Giraffine characteristic. The Okapi lives in pairs in the deepest recesses of the forest.
We are acquainted with a few extinct forms, belonging to Giraffa, which are extra-African in range. G. sivalensis is from the Pliocene of the Siwalik Hills in India, G. attica from Greece. These remains, however, do not include the top of the skull, so that it is doubtful whether their horns were as in G. camelopardalis.
A closely-allied genus is the extinct Samotherium. This flourished in Miocene times, and its remains have been found in the Greek island of Samos. The neck and limbs are shorter than in the Giraffe, and the horns, longer than in Giraffa, are placed just above the orbit upon the frontal bones alone, instead of upon the boundary line of frontals and parietals as in Giraffa. In several ways, therefore, the existing Giraffe is a more modified or
specialised animal than its forerunner of the Miocene. In the latter, the male alone carried horns, and in neither sex does the unpaired median bony excrescence appear. The remains of this genus (probably even the same species, S. boissieri) also occur in Persia.
Helladotherium (there is but one species, H. duvernoyi) has its four limbs of nearly the same length; the skull of the only known example is hornless; the neck is shorter than in Giraffa. It is known from the Miocene deposits of Pikermi in Greece.
Palaeotragus is a genus which is not referred to the Giraffidae by all systematists. Its very name, given to it by the eminent French palaeontologist M. Gaudry, indicates his opinion as to its Antelopine affinities. The chief and indeed (according to Forsyth Major[[200]]) the only reason for placing this Ruminant with the Antelopes is the large size of the horns. They undoubtedly suggest the horn cores of Antelopes. But they are placed wider apart than in those animals. It is thought that the hornless Camelopardalis parva is the female of this species, which is from Pikermi.
Rather more different from Giraffa is the extinct genus Sivatherium, from the Siwalik deposits of India. Here again there has been some discussion as to its affinities. Some place it in the neighbourhood of Antilocapra, but most palaeontologists now regard it as a Giraffe. The main peculiarity of this large beast was the existence of two pairs of horn cores; the larger are upon the parietal bones, and are of a palmated form, with a few short tines, which are highly suggestive of those of the Elk (Alces). The shorter anterior pair are upon the frontal bones. The neck is short, the limbs of equal length, and there are no additional toes upon the limbs. Sivatherium was almost as large as an Elephant, and in restorations it is depicted as having a fleshy dilated nose like the Saiga Antelope; this view is based upon the position and size of the nasal bones. Hornless skulls have been identified as the female of Sivatherium.
Vishnutherium, Hydraspotherium, and Bramatherium are allied genera.
Fam. 8. Antilocapridae.—This family contains but one genus and species, the N. American "Pronghorn," Antilocapra americana. This animal deserves a family to itself on account of the singular structure of the horns, which are intermediate in character
between those of the Deer and those of the Antelopes. They are unquestionably "hollow-horned" Ruminants, in that there is an osseous horn core, upon which lies the actual horn. This, however, is softer than in Bovidae, and is semicorneous. It is, indeed, more like the velvet of the stag's horn. Moreover the horn is branched, and there are sometimes even three prongs. Furthermore, it is now certainly known that the Pronghorn sheds its horns not merely occasionally, but with definite annual periodicity. It so far resembles the Deer. But it must be borne in mind that in the Deer the horn shedding is a twofold process. There is first of all the stripping off of the velvet, and secondly the shedding of a portion of the horn core down to the burr. What happens in the Prongbuck is the shedding of the true horn only ( = the shedding of the velvet), not of the horn core. It appears, however, that occasionally (once in their lifetime?) certain undoubted Antelopes may cast their horns.[[201]] Another external character of this animal is the total absence of "false hoofs," the last vestiges of the second and fifth digits. The Pronghorn is a gregarious creature running in bands of six up to hundreds.