RHINOCEROS LEPTORIIINUS. 371 



importance. The termination of the middle valley is angular (as in 

 the sketch) and there is a very pronounced combing process, emitted 

 from the outer side, and projected across so as to terminate not far from 

 the end of the crochet. The projection of this plate is much more con- 

 siderable than is shown in the drawing, and agrees very much with 

 that of R. megarhinus in Jourdan's big drawing (PI. XXXII. fig. 2), 

 with the allowance for the latter being more advanced in wear. The 

 posterior valley is very deep, down to the very bottom of the crown. It 

 is large and lined with a very thick coat of cement. The general contour 

 of the crown of the tooth is not prismatic, as in R. tichorhinus. The 

 opposite sides (inner and outer) converge towards each other quite as 

 much as in R. hemitcechus or It. megarhinus, but the crochet forms a 

 much larger plate than in the latter. The anterior outer vertical groove 

 is very angular and pronounced, forming a well-marked narrow step, 

 where seen in the section. No basilar mammilla on the inside between 

 the barrels. The posterior barrel is narrowed inside, into a kind of 

 oblique vertical keel, not round and bulging as in the drawing. Besides 

 the large combing process, the posterior termination of the transverse 

 valley throws up from below a pillar, which is not laterally attached. It 

 is represented by the posterior vallicular mammilla in the figure. The 

 anterior bourrelet is very pronounced and gaping, i.e. the interspace is 

 well marked. 



The most peculiar character probably consists in the form of the 

 ' barrels.' The posterior barrel is constricted about half way up. 



Dimensions. — Length of outer surface, 2'3 in. Length at middle along crochet 

 to outer edge of posterior valley, 2 - in. Length, inner side, near base, 1-6 in. 

 Greatest transverse diameter at base, 2'5 in. Greatest transverse diameter near 

 top where broken, 1*4 in. Greatest transverse diameter of posterior division 

 (base), 1*9 in. Greatest transverse diameter of ditto at top, - 8 in. The two last 

 measurements show the amount of convergence. 



[In Dr. Falconer's Note-book a description is given of two other 

 molars of Ehinoceros in the Nice Museum : — No. 39, a third premolar, 

 and No. 40, a fragment of the first true molar, left side. Inspecting the 

 latter it is stated 'there is no indication that the crochet was joined on 

 to the anterior barrel, so as to form during wear a third pit or well, as 

 in R. tichorhinus. This confirms the indication of the sixth molar des- 

 cribed above. Further, there is not a vestige of a basal bourrelet, 

 although the barrels are not ground so low down as to have caused its 

 disappearance.' — Ed.] 



V. — Description of Remains of R. Leptoeiiinus in the Museum at 



Rome. 



April and May, 1859. 



A. In Professor Ponzi's Collection from the Gravel Beds of Ponte Molle. 



The Rhinoceros remains are much rarer than those of Elephant. 

 The only specimens are : — 



1. Two last true molars, upper jaw, left side. (Plate XXXII. fig. 6.) 



2. A penultimate upper premolar, left side, much worn. 



8. A finely preserved left upper milk molar. (Plate XXXII. fig. 7.) 



b d 2 



