362 



RHINOCEROS. 



Rh. leptorhinus. Rh. ticltorlnnus. 

 In. Lin. In. Lin. 



Antero-posterior extent of last two molars . 43 39 



penultimate molar .20 19 



Transverse diameter of base of crown of penultimate 



molar ..... 



, g 



In the present specimen of the jaw of the leptorhine 

 Rhinoceros (fig. 133), the worn state of the last two 

 molars shows that it had belonged to an old individual : 

 Fig. 134. but the difference of size is equally mani- 

 fested by the specimen of a fragment of the 

 left branch of the lower jaw of the Rhino- 

 ceros leptorhinus (fig. 134), also obtained by 

 Mr. Brown from the fresh-water deposits 

 at Clacton, and containing the last three 

 molars, in the same state of attrition as those 

 in the jaw of the Rhinoceros tichorhinus (fig. 

 124). There is a difference also in the pro- 

 portional size of the posterior lobe of the 

 last molar tooth, which is greater in the 

 Rh. leptorhinus. The lower terminations of 

 the internal depressions of the molars are 

 Rhinoceros lepto- j angular and less narrow in the Rh. 



rhinus. ^ nat. size. 



Walton. leptorhinus ; and the three inner columns or 



prominences of the molars are less flattened. 



The specimen of the fore part of the lower jaw of a 

 somewhat younger leptorhine Rhinoceros, obtained by Mr. 

 Brown from the fresh-water deposits at Clacton, Essex, 

 and containing the second, third, and fourth premolars in 

 situ (fig. 135), yields a specific character in the larger 

 proportional size of the second premolar ; which will be 

 recognized by comparing the annexed figure with fig. 

 128, and is demonstrated by the following admeasure- 

 ments : 



