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Show 184 PROF. W. H. FLOWER ON THE MUSK-DEER. [Mar. 16, The incisors are of rather peculiar form, the central being straight and awl-shaped instead of expanded and diverging, as not only in most Deer and Antelopes, but also, in a still more marked degree, in thelVa-gulina. But the Reindeer, as Sir Victor Brooke lately pointed out*, has incisors not unlike those of the Musk ; and the same or a closely similar form is not uncommon among the Bovida. This is rather an absence of specialization than a mark of affinity. The great development of the upper canine teeth of the male is a remarkable characteristic of Moschus, and one on which much stress was formerly laid in separating it from the Deer. Most of the latter, however, have canines ; and their great size in the Muntjaks forms a considerable approximation to the condition in Moschus. But Hydropotes offers a crucial test of the value of this character. This singular genus agrees with Moschus in the great size of the canines as well as the absence of antlers (in these cases apparently correlated phenomena). If Moschus is to be separated from the Cervida on the strength of these two most striking external characters, Hydropotes must go with it, and the family Moschida will consist of the two genera Moschus and Hydropotes^-an arrangement which may satisfy some zoologists; but, as shown by Sir Victor Brooke in his description of the skull of Hydropotes, these animals differ greatly in many important respects ; in fact, in the form of the base of the cranium, they are as widely removed from each other as are any of the true Deer,-Moschus, with its small rugged auditory bulla, resembling the Muntjak and the Roe ; while Hydropoteshns the same part smooth and inflated even in a greater degree than the Axis and Hog- Deer, and more resembling some of the Antelopes. The question of the affinity of these two forms will receive further elucidation when the visceral anatomy of Hydropotes is known ; but there is at present but little reason for supposing them nearly related. As it is a very characteristic feature in the Bovida to have entirely lost the upper canine teeth (very few indeed possessing any, and these always very rudimentary), their presence on such a large scale in Moschus is further corroboration to the evidence derived from the molars that it is not intimately allied to that family. On the other hand, little weight can be attached to this character as showing any very near affinity to the Tragulina. The excessive growth of a particular tooth is an instance of specialization, and occurs so often in forms so remotely allied to each other as Machairodus, Trichechus, Sic, that it can only be taken as evidence of relationship between animals otherwise very nearly akin. In the present case it is probably adaptive, and follows the general tendency among all Artiodactyles, Suine as well as Ruminant, to possess either tusk-like canines or frontal appendages, these being, with some notable exceptions, complementary to each other in development. All the early Artiodactyles had canines, at first of moderate proportions; but it was not long before the tusks became immensely developed in the * " O n Hydropotes inermis and its Cranial Characters as compared with those of Moschus moschiferus," P. Z. S. 1872, p. 522. t As in Dr. Gray's 'Hand-list of Ruminants in the British Museum,' 1872. |