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Show 1900.] STRUCTURE OF T H E MUSK-OX. 695 concave interior surface. Through this arrangement the plantar surface of the foot becomes concave, and in the middle there is a broad opening between both hoofs. This opening is about as broad as half the transverse breadth of each hoof measured separately. Through this opening or fissure between the hoofs, hair, growing between the fingers, protrudes to the lower surface of the foot, which otherwise of course is naked. But the hair of the leg hangs down on the hoofs, so that it is only a rather small portion of them anteriorly which is visible. Posteriorly this fissure is terminated by a transverse pad which very firmly unites both hoofs all the way to the treading surface, aud consequently shares in supporting the animal. The hoofs are a little irregular in shape, but not much so ; and it can hardly be said that one hoof is more pointed than the other, because both are almost equally rounded. The fore hoofs are a little longer than those of the hind legs, so that in an adult bull the former measure about 12 cm. in length and the latter about 10 cm. From what has been said above, it will be seen that the shape of the hoof is very different from that of the hoof of Bos and still more from the narrow pointed hoofs of the Caprince. In these animals the toes are not so closely and firmly connected posteriorly as in Ovibos. It seems more than probable that the shape of the hoofs of the Musk-ox is an adaptation acquired secondarily; and such a statement is plainly confirmed on comparing the similarly broadly rounded hoofs of the Beiudeer, which lives under similar circumstances to the Musk-ox, with the pointed hoofs of other Deer. The lateral hoofs of the Musk-ox are also comparatively large, and have a very characteristic shape and aspect because the vertical " Krallenplatte " does not together with the " Krallensohle," to use Boas's terminology \ form an even cap over the rudimentary phalanges, but grows out so that it protrudes a good deal beyond the latter. This gives the lateral hoofs an irregular appearance as if they were torn. Although they are broad the lateral hoofs are not prolonged iu such a way as in the Beiudeer, and consequently the convergence with the latter animal is not extended to these parts. Sect. 3.-DESCRIPTION OF THE SKULL OF THE MUSK-OX. The osteology of the Musk-ox has been carefully described by Owen, Biitimeyer, Dawkins, and others. A renewed description of already known facts is consequently unnecessary, and it is not my intention to give one on this occasion. But I will proceed to' a discussion of the characteristics of the Musk-ox skull based on a comparison with other forms, and through this I hope to bring forward some points which have been hitherto neglected or misinterpreted. 1 Boas, " Zur Morphologic der Wirbelthier Kralle," Morph. Jahrb. xxi. 1894. |
