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Show 1869.] DR. J. E. GRAY ON THE AFRICAN RHINOCEROS. 225 and a short hind foot like the skeleton of a human hand, with the short metatarsi and thumb springing from one side of the base of them, as if it might be opposable. The fingers and toes five; the fingers long, slender, the second, third, and fourth very long, of four joints, lower large, the last joint small and short; the first and third toes of three joints, the first strongest, the fifth shortest. The hind feet much like the human hand. The toes short; the thumb short, strong, from the base of the metatarsus, the other four toes longer, subequal, the third or middle toe being rather shorter, the second and fourth subequal, and the fifth rather the shortest and most slender. Sternal bone very narrow, only forming a large, oblong, elongated ring. See also Wagler, N . Syst. A m p h . t. 5. DESCRIPTION OF PLATE XV. Fig.l. Trionyx formosus, p. 217. 2. Baikiea elegans, p. 222. 7. O n the Incisor Teeth of the African Rhinoceros. B y Dr. J. E . G R A Y , F.R.S. The skull of the nearly adult female specimen of Rhinaster keitloa in the British Museum killed by Mr. Jesse in Abyssinia has the small intermaxillary bones well preserved. They are not united together in front; the dental edge has unfortunately been injured in the carriage from Abyssinia; but they each exhibit small cylindrical blunt rudimentary incisor teeth. The intermaxillary of the right side has a large tooth on the hinder part; the intermaxillary on the left side has a middle-sized tooth in the middle of the dental surface, and a very small rudimentary tooth behind it near the hinder edge of the bone. These teeth would induce one to believe that in the perfect state there are two, or perhaps three, incisors in each intermaxillary ; for close to the symphysis is a small alveolus in the front part of the dental margin on each intermaxillary ; but these do not now contain any rudimentary teeth. Professor Vrolik has described the lower incisor teeth in the skull of the young African Rhinoceros (see Ann. d. Sci. 1837, p. 20, t. I B ) ; but I believe that they have not before been observed in the adult animal. If the observations of M M . Lefebvre, Petit, and Dillon, in the ' Voyage en Abyssinie,' Paris, are to be relied on, there must be other Rhinoceroses in Abyssinia than those we have yet seen. They state, " II y a plusieurs especes de Rhinoceros en Abyssinie. II y en a qui ont deux, trois et quatre cornes : cela est certain ; il l'est moins qu'il y en ait a cinq et six, mais on l'assure. Sur l'animal vivant elle est toujours mobile, sans os a l'interieur " (pp. 26, 27). |