374 



KHINOCEROS. 



is compressed with the peculiar torsion of R. megarhinus. It is deeply 

 grooved at the anterior side. The disc of wear points diagonally back- 

 wards. (This specimen was named JR. leptorhinus by Prof. Owen.) 



Dimensions. — Length of crown, outer surface near top, 1-8 in. Length of ditto 

 in middle, 1-55 in. Length of ditto, inner side near base of barrels, 1/1 in. Length 

 of outer surface near base, 1*5 in. Transverse diam. anter. end, 1/7 in. Trans- 

 verse diam. posterior end, 1-6 in. 



The lower jaw specimen is a mutilated fragment of the alveolar por- 

 tion of the left ramus broken off at one-third of its height. It com- 

 prises the antepenultimate and penultimate true molar in place, and 

 the anterior half of the socket of the last true molar behind. The ante- 

 penultimate is worn in front down to the line of commencement of the 

 outer anterior oblique bourrelet, and has the discs confluent, but the 

 posterior crescent is not much worn, less so than in the penultimate of 

 the Montpellier cast. The anterior end bears a disc of pressure. The 

 penultimate has the apices in the first stage of wear ; the disc of the 

 posterior crescent is distinct from, and at a lower level than, the an- 

 terior. The posterior end bears a well-marked pressure surface. 



Dimensions. 



Compared with the R. megarhinus cast, they agree in form and pro- 

 portions, but are much smaller. They have each the same oblique 

 bourrelet ridge to each barrel (one in front of the tooth, the other 

 behind) on the outer surface. There is a very thick coat of cement 

 below. They differ entirely from the square form and thick enamel of 

 Ji. tichorkinus, with two detached molars of which from Kent's Hole I 

 compared them. I was not able to extend the comparison to R. hemitce- 

 chus, but I believe them to be of R. megarhinus. The specimen is 

 from Ponte Molle (Professor Ponzi's ' volcanic sand '). 



B. In the Sapienza Museum, from Monte Sacro. 



Examined a very fine penultimate true molar, upper jaw, left side 

 (No. Ill) of a fossil Ehinoceros from Monte Sacro, showing all the cha- 

 racters in the best condition of wear ; both the collines and crochet are 

 worn, but the posterior edge of the hind valley is intact (PI. XXXII. 

 fig. 4). The tooth is of very large size, larger than the detached 

 tooth of B. he?nitojchus, with which it was compared. 



