24 
MOLAR TEETH AND OTHER REMAINS OE MAMMALIA. 
side of fig. 7), joining on to the median tubercle, which thus appears to be merely 
a portion of the cingulum, and is not isolated as in Mhinoceros iramdicus. The 
cingulum is continued posteriosly for a very short distance along the internal face 
of the median collis {left side of fig. 7 and right side of figure 9) ; it then stops 
abruptly, and for a space of half an inch in length, this surface has no trace of a 
cingulum ; posteriorly to this space the cingulum again suddenly commences as a 
bold wide ledge {well seen in fig. 9) very different from the slight cingulum at 
this part in the Burmese specimens {right side of fig. 1, plate 5). This ledge, two- 
tenths of an inch in width, is continued along the posterior surface of the tooth till 
it joins the outer wall of the posterior valley. The pass to the posterior valley is 
very sharp (while it is broad and flat in R. iravadicus)^ and the valley itself long and 
oval, and less deep than in the Burmese species. 
The cingulum is placed much higher up on the crown than in R. iramdicus ; 
its lowest portion is *8 inch above the neck of the tooth : the height of the summit 
of the median tubercle is *7 above the neck. In consequence of the median tubercle 
being situated externally to the entrance of the valley, instead of within it, as 
in R. iravadicus^ the interval between its summit and the outermost portion of the 
median valley is greater. This interval in the Siwalik specimens is respectively 1 *6 
inches and 1*7 inches, while in the Burmese specimens the same interval is only 
1‘2 inches. The interval between the centre of the pass leading into the posterior 
valley, and the centre of the internal surface of the median collis, is in the Siwalik 
specimens IT inches, and in the Burmese species 0’9 inch. The length of the 
internal surface of the specimen drawn in figure 7 is 2’2 inches, or *3 inch longer 
than the corresponding surface of the molar of R. iramdicus ; the antero-posterior 
diameter of the anterior collis, taken through the antecrochet, in the specimen 
drawn in figure 7, is 1’3 inches ; the corresponding line in the molar of R. iramdu 
CHS is IT inches. Erom the parallelism of the dentine-surfaces of the two colles in 
the molars of R. planidens, I am inclined to think that the antero-external angle 
of the tooth was not produced into a buttress. The worn-crown would present two 
permanent fossettes only, although for a very short period there might be a very 
small third fossette, placed internally to the crochet, the median valley being very 
shallow at the crochet. 
The molars of this species are distinguished from those of R. sinensis by the 
presence of the tubercle at the entrance of the median valley, and by the valley 
becoming deeper as it passes outwards. 
Erom the molars of R. sivalensis the present specimens are distinguished by 
the presence of the large tubercle at the entrance to the median valley, and the 
very prominent cingulum on the inner and anterior surfaces, as well as by the 
presence of the large antecrochet and the temporary third fossette. 
The presence of only two permanent fossettes on the crown distinguishes the 
present specimens from the molars of R. Itidicus, R. platyrhinus, R. namadicus, and 
R. palceindicus. The absence of any combing-plate distinguishes these teeth from 
( 4.2 ) 
