1870. J DENTAL CHARACTERS OF RHINOCEROSES. 453 



tlie most specialized of all the living Rhinoceroses. The broad form 

 of the front of the lower jaw, as compared with R. bicornis, is quite 

 well seen in these very young specimens. 



With regard to the molar teeth, the same kind of difference 

 occurs hetween these forms as between the two Indian one-horned 

 species. The larger one has a greater complexity of arrangement, 

 derived from (he more frequent union of crochet and crista, cutting 

 off an accessory valley. But it must be noticed that there is an 

 extraordinary variation in this respect between two examples of R. 

 simus of nearly the same age in the British Museum, so great, 

 indeed, that, if supported by other characters, they might he taken to 

 indicate specific distinctness. In fact they either do this or show 

 that the precise pattern of the enamel-folds of the molar teeth, so 

 much relied upon by palaeontologists to distinguish species, is a 

 lather uncertain character. In one of these skulls (No. 1003a) 

 the crochet and crista are united in all the premolar and molar 

 teeth of both sides. In the other (No. 1003 b), an older specimen, 

 and somewhat smaller, though presenting all the general characters 

 of the species, they are united only in the left second premolar, in 

 both third premolars, in both first molars and in the right third 

 molar. The want of symmetry throws some doubt upon the value 

 of this character*; otherwise it might, combined with the smaller 

 size and narrower nasals of this specimen (perhaps only sexual dif- 

 ferences?), lend some countenance to the common belief among 

 African sportsmen and travellers, that there is a second large 

 species allied to R. simus. 



In the smaller African rhinoceros, R. bicornis, the crochet and 

 crista of the molar teeth are both well developed, but rarely united 

 in the true molars, though frequently so in the premolars. Whether 

 there is one or more species of this form, has long been debated by 

 zoologists ; but those who have given their verdict for two have 

 founded their decision solely on external characters, chiefly the form 

 and size of the posterior horn, and no attempt has ever been made 

 to show whether any osteological or dental characters were correlated 

 with these. In fact, until very recently there were no materials ac- 

 cessible for the investigation. The acquisition by the British 

 Museum of two complete skeletons of the reputed R. keitloa, and 

 others of R. bicornis, with the horns attached, has, however, 

 rendered the investigation a practicable one. I have not yet had 

 the leisure to make the careful examination of the whole skeleton 

 which would be desirable ; but, comparing the skulls and teeth of 

 perfectly adult individuals presenting both varieties of horns, I have 

 not been able to detect any differences either of size, general pro- 

 portions, or relations of the various bones to each other, that could 

 reasonably be called specific. All that can be inferred from this is, 

 that I have not at present seen any thing derived from osteological 

 or dental structures to confirm the belief in the existence of more 

 than one species of the smaller type of African rhinoceros. Other 

 observers may, with more ample materials, be more fortunate ; and I 



* And its variability as before noted, in specimens <>!' undoubted E. itnicornis. 



