RHINOCEROS. 589 



small horns, moderately developed incisors in both jaws ; and the 

 same teeth are present in the nearly allied extinct two-horned Rhino- 

 ceros called after its discoverer Schleiermacher. The incisors are 

 well developed in both the existing unicorn Rhinoceroses, Rh. indicus 

 and Rh. sondaicus ; but they attain their largest dimensions in the 

 singular extinct hornless species, the Rhinoceros incisivus of Cuvier, 

 which makes the transition to the extinct genus PalcBotherium, and 

 forms the type of the aberrant subgenus Acerotherium of Dr. Kaup : 

 (PL 138, fig. 1). The normal incisive formula is; — 2^ = 8: the 

 median pair being the largest above and the smallest below : in the 

 existing species the smaller incisors are disproportionally minute, and 

 usually have no permanent successors, or are soon shed ; the larger 

 incisors are preceded by deciduous teeth which they succeed and 

 replace. In the under jaw of a Sumatran Rhinoceros, now before me, 

 the extremity of which is figured in Plate 138, fig. 15, the tips of 

 the large permanent outer pair of incisors {i 2) are visible, but have 

 not pushed out their deciduous predecessors {d 2) ; and the sockets 

 (d 1) of those of the two small median incisors {i 1) are also retained. 

 In one of the extinct species of Rhinoceros from the Himalayan 

 tertiary beds Dr. Falconer informs me that there are six incisors in 

 both jaws : the typical number was, therefore, retained in this 

 ancient species, as in the contemporary Hippopotamus of the same 

 formations. Cuvier believed that the ex-incisive character of the 

 two-horned Rhinoceros of Africa was absolute. "Not only," he 

 observes, " is its hide without folds, not only has it constantly two 

 horns, but it has never more than twenty- eight teeth, all molars ; 

 and never possesses incisors, nor even a place for them at the 

 anterior extremity of its jaws."(l) 



affording extra support to the horn-bearing bones of the face whence the name tichorhinus 

 given by Cuvier to this most common of the extinct Rhinoceroses of our Northern Hemis- 

 phere. 



(1) " Non-seulement sa peau n'a point de plis; non-seulement il a constamment deux 

 comes, mais il n'a jamais que vingt-huit dents, toutes molaires ; il manque toujours d'incisives, 

 et n'a meme point de place pour elles a I'extremite anterieure de ses machoires." ' Ossemens 

 Fossiles,' 4to. 1822, tom. ii. pt, 1, p. 27. The otherwise excellent zoological descriptions of the 

 two-horned Rhinoceroses in Dr. Smith's ' Illustrations of the Zoology of South Africa, do not 



