1876.] DENTAL CHARACTERS OF RHINOCEROSES. 455 



overhang the occipital surface of the skull. Nasal bones narrow and 

 pointed anteriorly. A well-developed nasal and a small frontal 

 horn separated by an interval. The skin thrown into folds, but not 

 so strongly marked as in A. Ceratorhinus, Grav, P. Z. S. 

 (1807) *. 



1. C. SUMATRENSJS, CllV. (R. A. 1817). 



C. sumatranus, Raffles (Trans. Linn. Soc. vol. xiii. 1822, p. 268). 

 C. niger, Gray (Hand list Edentates &c. Brit. Mus. p. 48, 1873). 



2. C. lasiotis, Sclater (P. Z. S. 1872, p. 493). 

 (Anatomical characters unknown.) 



C. In the adults the incisors are either quite rudimentary or 

 entirely wanting. The post-tympanic and post-glenoid processes not 

 united below the auditory meatus. Occipital crest produced back- 

 wards, and overhanging the occipital surface of the skull and con- 

 dyles. Nasal bones thickened and rounded or truncated in front. 

 An anterior and posterior horn in close contact. Skin without any 

 definite permanent folds. Atelodus, Pomel (1853)-f\ 



a. Smaller size. Incisor teeth always present in the young, and 

 sometimes persistent as rudiments through life. Molar teeth with 

 crista and crochet rarely united. Front end of mandible deep and 

 compressed. 



1. A. bicornis, Linn. 



R. africanus, Cuv. (R. A. 1817). 



R. keitloa, A. Smith (Cat. S. A. Mus. p. 7, 1837)- 



* These terms may be taken either as generic, or as indicating natural sec- 

 tions of the Linnean genus Rhinoceros. The great differences in the visceral ana- 

 tomy (referred to above) between this species and the first, tend to support the 

 former view. Their significance will, however, be better understood, when the 

 internal anatomy of the third section is known, and also that of B. sondaicus. 



t Pomel divided the genus Rhinoceros, Linn., into three subgenera : — 



1. Acerotherium, Kaup. 



2. Rhinoceros, Linn. 



3. A/i lodus, Pomel. 



The last is thus defined. " Os nasaux portant une ou deux cornes ; pied a 

 trois doigts. Lne ou deux paires d'iucisives inferieures caduques en forme de 

 simple tubercule souvent a peine sorti de la gencive, ou nulles ; pas de plis a 

 la peau sur les especes vivantes." 



The following are the species assigned to this group : — 



A. elatus (Croizet & Jobert) ~| 



A. leptorhinus (Cuv.) | extinct 



A. tichorhirms (Cuv.) j 



A. aymardi (Pomel) J 



A. bicornis (L.) I 



A. keitloa (A. Smith) I existing. 



A. simtis (Burchell) 

 ("Catalogue methodique et descriptif des vertebres fossiles decouverta dans 

 lebassin hydrographique superieur de la Loire." Part ii.. in ' AnnaleB scientifiqucs, 

 litteraires et industrielles dc l'Auvergne,' torn. xxvi. 1853, p. 114.) 



