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Show 180 PROF. W. H. FLOWER ON THE MUSK-DEER. [Mar. 16, In the following characters Moschus agrees entirely with all the Pecora and differs from the Tragulina. 1. The placenta is cotyledonous*, whereas in the Tragulina it is diffuse, as in the Suina and Tylopoda. 2. There is a complete psalterium or third cavity to the stomach. 3. The left brachial artery arises from a common innominate trunk, instead of coming off separately from the aortic arch as in Tragulina, Tylopoda, and Suinaf. 4. The odontoid process of the second cervical vertebra is in the form of a crescent hollow above, instead of being a conical tuberositv as in Tragulina and Suina. 5. The auditory bulla is simple and hollow within, instead of being filled with cancellated tissue as in Tragulina, Tylopoda, and Suina. 6. The outer metacarpal and metatarsal bones are rudimentary, and do not extend the entire length of the middle metacarpal and metatarsals. 7. The distal extremity of the fibula is represented by a distinct malleolar bone of peculiar shape, articulating with the outer surface of the lower end of the tibiaj. 8. The molar and premolar teeth of Moschus are truly Cervine, though more compressed throughout the series than in most Deer. In consequence of this, the first upper premolar has the inner crescentic lobe but little developed; but its presence can be distinctly seen in specimens that are not much worn, and there is no tendency to that great disparity of breadth between the two anterior premolars and the true molars seen in the Tragulina, whose teeth retain much of the old Xiphodon type§. It is scarcely necessary for the present purpose to enumerate numerous minor osteological characters (many of which are pointed * For a description of the placenta of Moschus, we are indebted to Pallas (loc. cit.). t The only recorded exception to the ordinary origin of the left brachial artery in the Pecora is in the Giraffe, where Prof. O w e n found that the arch of the aorta, after distributing the vessels to the heart itself, gives off first a large innominate, which subdivides into the right vertebral artery, the right brachial artery, and the common trunk of the two carotids, secondly the left brachial artery, thirdly the left vertebral artery (Trans. Zool. Soc. vol. ii. p. 229). But Joly and Lavocat describe, in the Giraffe dissected by them, a common innominate trunk (or anterior aorta) as in the Ruminants generally, giving off both brachials and carotids ("Recherches sur la Giraffe," M £ m . Soc. d'Hist. Nat. de Strasbourg, t. iii. 1845, p. 103); and Prof. A. H . Garrod informs m e that the same distribution of the great vessels occurred in two specimens which he had examined. J In Tragulus the upper part of the fibula is present as a long slender style, but the lower end ankyloses at an early age with the tibia. The latter is the case with Hyomoschus crassus and H aquaticus, according to A. Milne-Edwards; but in a perfectly adult specimen of the last-named animal in the Museum of the Royal College of Surgeons, the malleolar bone is still free, though not of the very characteristic form it possesses in all true Ruminants. § In all Deer the first upper premolar has three roots, and the crown is formed by an inner and outer crescent. In Tragulus this tooth has but two roots, and a simple compressed crown. In Hyomoschus, though the crown resembles that of Tragulus, the additional inner root is present. In this respect, as in the condition of the fibula, Hyomoschus comes nearer to the Deer than does Tragulus. |
