450* ON THE CRANIAL CHARACTERS OF RHINOCEROSES. [May 16* 



b. Larger size. Incisor teeth, if ever present, disappearing very 

 soon after birth. Molar teeth with crista and crochet generally 

 united. Front end of mandible depressed and spatulate. 



2. A. simus, Burchell (Bull. Soc. Philomat. p. 96", 18 IT). 

 A. oswellli, Gray (P. Z. S. 1853, p. 4(3). 



In reference to the name of this group, Coelodonta (Bronn, 

 Jahrbuch fur Mineralogie, 1831, p. 51) was proposed for some 

 teeth supposed to belong to a new genus allied to Rhinoceros, but 

 subsequently identified as those of the well-known 11. tichorhinus, 

 Cuv.* It can scarcely be retained, however, for the group now 

 under consideration, as its definition would include R. unicornis, 

 and exclude many of the species without incisor teeth. It was, in 

 fact, never equivalent to Pornel's Atelodus, though it might be used 

 (as by Dr. Gray, loc. cit. 18u"7) by any one who thinks fit to 

 separate R. tichorhinus generically from all the other members of 

 the family. In the Catalogue of the bones of Mammalia in the 

 British Museum (18(i2), Dr. Gray uses Rhin aster for all the species 

 of existing African rhinoceroses ; but in the memoir so often referred 

 to above (1807) this name is limited to R. bicornis and R. keitloa, 

 and Ceratotherium is introduced for R. simus. Rhinaster, as ap- 

 plied to the Rhinocerotidse, appears to be later than Atelodus. It 

 was, moreover, proposed by Wagler (Syst. Amphib. 183U) as a 

 substitute for Illiger's genus Condylura (Insectivora), on account of 

 the latter being inappropriate ; but it has not been generally adopted. 

 As the termination of such a term as Ceratotherium, by common 

 consent of zoologists, has hitherto been restricted to extinct genera, 

 its application to R. simus is inconvenient. Fortunately, in the 

 grouping proposed above, the name is unnecessary, as the members 

 of the family with the incisor teeth small or absent form a well- 

 characterized, even if somewhat artificial, generic group, which 

 scarcely needs further subdivision. 



Although most of the known extinct species of Rhinoceros may be 

 arranged under one or the other of the above sections, the definitions 

 would have, as, indeed, might be expected, to be considerably modi- 

 fied to include them. Thus R. schleiermacheri, Kaup, of the late 

 European Miocenes, though allied to R. sumatrensis in possessing in- 

 cisor teeth and two horns, and so far coming under the definition of 

 Ceratorhinns, retains the central lower incisors of Rhinoceros proper, 

 and has the post-glenoid and post-tympanic processes united, as, 

 indeed, have all the extinct forms that I have examined. On the 

 supposition that this species is the direct ancestor or representative 

 of the Ceratorhinns group of modern times, the presence of the four 

 inferior incisors, as a more generalized character, is quite natural ; but 

 the structure of the squamosal is not so easy to understand, as being 

 more specialized than in the modern species. Precisely the same 

 occurs with the former representatives of the Atelodus group, of 



* S. antiquifatis, Blum., is the earliest name for this species, and is adopted 

 by Brandt and Dr. Falconer, though Cuvier's name still holds its ground with 

 most authors. 



