A. Tragulina

As the Tragulina are undoubtedly the most ancient of the Selenodontia it will be logical to commence with an account of them.

Fam. 4. Tragulidae.—This family comprises a number of small Deer-like animals, which are really in many points more related to the Pigs than to the true Deer. They are known as Chevrotains; and the term "Deerlet," introduced by Professor Garrod, is certainly appropriate, since they have the aspect of very small and hornless Deer. If it were not for their Artiodactyle feet one might at a glance confuse these creatures with some Marsupial type. The family is Oriental and West African in range. The two genera (whose individual peculiarities will be considered later) differ from other Artiodactyles in a number of rather important characters.

Fig. 147.—Indian Chevrotain. Tragulus meminna. × ¼.

They are absolutely hornless in both sexes. The canines are present in both jaws, and are especially well developed in the upper jaw. The dental formula is I 0/3 C 1/1 Pm 3/3 M 3/3. In the skull the tympanic bulla is usually, as in the non-ruminating Artiodactyles, filled with loose bony tissue. The feet (usually) have the four toes of the Suina, and are therefore in a more primitive condition than in Deer and Antelopes. But as the middle metacarpals are fused in Tragulus (though separate in Hyomoschus) they are a stage further than are the Pigs, in the direction of the typical Ruminants.

The stomach is comparatively simple, thus offering intermediate characters between the Pigs and the Ruminants; there are but three separate compartments. A highly-interesting character is afforded by the placenta. This is in the present family of the diffuse kind, not presenting the separated and tufted cotyledons of the Ruminant placenta. This we may fairly assume is a further proof of the less-specialised characters of this group as compared with the Ruminantia, a view, however, which is not universally accepted. While the molars have the selenodont character of other Pecora, the premolars are more adapted for cutting, with sharp edges.

The genus Tragulus consists of several species (e.g. T. stanleyanus, T. napu, etc.), which have been aptly compared in external appearance to certain Rodents such as the Agoutis. The legs are delicate and slender, hardly "thicker than an ordinary cedar pencil." These creatures have got among the Malays a considerable reputation for astuteness, embodied in the saying, "Cunning as a kanchil." The male has tusks, which greatly contributed to the confusion of this creature with the totally different Musk Deer, Moschus moschiferus. It is even said to suspend itself by their aid to the branches of trees, and so avoid danger.

Hyomoschus (or Dorcatherium as it should properly be called) is West African. Its rich brown colour, with spots and stripes, is much like that of the Chevrotains, but it has shorter limbs. The only species is D. aquaticum, which is sometimes called, on account of its frequenting the banks of streams, the Water Chevrotain. Remains of this genus occur in Miocene and Pliocene strata of Europe.

The separate metacarpals, comparatively simple stomach, absence of horns, diffuse placenta, and spotted pelage are features which argue the primitive position of these animals among existing Artiodactyles.

Besides the two existing genera which have just been treated of, there are a number of extinct genera undoubtedly belonging to the same group.

Gelocus (Eocene and Oligocene in range) is a European genus known from France. It differs from the living members of the group by the fact that the second and fifth toes on both hind- and fore-feet are represented, as in certain Deer, by rudiments at the upper and at the lower end only; they are deficient in the middle. The middle large metacarpals, though closely applied, are not fused. The metatarsals, on the other hand, are, or are not fused, according to the species. A later form is the genus Leptomeryx from the Miocene of North America. This genus departs from the typical Traguline structure in more than one point. The tympanic bulla is hollow instead of being filled with cancellated bone; the cuneiform is not fused with the cuboid and navicular, though the latter are with each other; the lateral digits of the hind-feet are rudimentary. The magnum and trapezoid, however, are fused. In the fore-feet the middle metacarpals are separate, and the lateral less perfect metacarpals have toes. The metatarsals are fused.

Not definitely referable to the Tragulidae, but coming near to them, are the Protoceratidae. Of this family there is but one well-known genus, Protoceras, from the Miocene of North America.

The skull is singularly reminiscent of Dinoceras, with which this quite Artiodactyle genus has, of course, nothing to do. It merely exemplifies the phenomenon of "parallelism." In general form it is peculiarly long and low. There are three pairs of bony protuberances: one, the largest, pair are situated on the maxillae rising up just behind the implantation of the canine teeth; the parietals have a second pair; and a third much more diminutive pair of bosses are upon the frontals, near their junction with the nasals. This description refers to the male; the female has only traces of the parietal bosses. These were all possibly tipped or sheathed with horn or roughened skin. The dentition of this genus is precisely that of the Tragulidae, i.e. I 0/3 C 1/1 Pm 4/4 M 3/3. The orbit is completely encircled by bone; the auditory bulla is not swollen; the premaxillae are small.

The nasal cavity is very large and open, the end of the nasal bones anteriorly being situated at about the middle of the skull; this would seem to indicate at least a flexible and long nose like that of the Saiga Antelope, if not a trunk.

The brain was of good size, and quite well convoluted.

The limbs are constituted on the Traguline plan; in the fore-limbs the middle metacarpals are quite free from each other, and the more diminutive lateral digits are complete. The metatarsals are free, but with a tendency to fusion; the lateral toes are only represented at the upper extremity. The carpal bones are separated.

This animal, which was about the size of a Sheep, though of more delicate proportions, was allied not only to the Tragulidae but to the Giraffidae; it is impossible to refer it definitely to either family.