42 
INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
Upper premolars. — There are unfortunately no perfect upper premolars in the 
collection ; hut the inner half of a well-worn right pm. -3 is represented in pi. X. 
fig. 2. This specimen 1 shows that there is no trace of a cingulum on the anterior 
collis (a), and merely an oblique ridge running downwards and backwards on the 
anterior aspect of the posterior collis (b) ; the two colles unite at their junction for a 
considerable part of their height. The corresponding portion of the left pm. 4 of 
the same individual (No. F. 135a) presents precisely similar features. 
Affinities. — That the present form is specifically distinct from all the existing 
Indian species of Rhinoceros is self-apparent ; and it will not be difficult to show its 
apparent distinctness from all the fossil species of the same country. In Madras 
two other species occur in a fossil condition ; the first of which appears identical 
with the existing R. unicornis , and is known by the slightly-worn third right upper 
true molar represented in pi. X. figs. 3, 3a, which was obtained several years ago by 
Mr. Foote from a turbary, and is interesting as showing the extensive range of this 
species in past times. 2 The second species, R. deccanensis, Foote, 3 is of pleistocene 
age, and, although of somewhat superior size, agrees with the present form in the 
absence of lower canines, and in the general plan of structure of the upper true 
molars. The teeth are, however, described as being markedly hypsodont, and 
without any appreciable quantity of cement, while in the upper true molars the 
external surface is nearly flat, and the colles are approximated and show no trace of 
any internal cingulum. In the premolars, however, there is a very strongly-marked 
cingulum completely surrounding the inner half of the crown, 4 and the inner half 
of the anterior colles appears less flattened. The premolars are moreover larger in 
proportion to the true molars, the antero-posterior diameter of p m. 4 being 1*55 and 
that of m.2 1*9, while in the present form the corresponding dimensions are 1T5 
and 1'7. In the mandible the arcuation of the inferior border, and especially the 
upward inclination of its anterior moiety, is very much more strongly marked, 5 and 
the bases of the crowns of pm. 2 and pm. 3 are placed on a considerably higher level 
than that of pm. 4, instead of in the same horizontal line. The symphysial channel 
appears wider, much less distinctly defined, and more open ; pm. 2 is apparently 
larger and more widely separated from its fellow of the opposite side, while there is 
a distinct cingulum at the two extremities of the outer surfaces of the premolars, 
but no trace of a mentary foramen below pm. 3. From the structure of that portion 
of the symphysis still remaining it appears probable that this part was rather shorter 
in the fossil. With the fossil rhinoceroses of the Siwaliks the present form has no 
affinity ; the only bicorn species ( R . platyrhinus ) having upper cheek teeth of a 
totally different type of structure. The Maragha R. persice 8 is also an entirely 
different form. 
1 It is highly probable that this and the next specimen belong to the same individual as the true molars. 
2 The artist has foreshortened the inner surfaces of the colles in fig. 3, which makes the crown look lower than it really 
is, but its true height is shown in fig. 3a. 3 Supra, vol. I. pp. 1-17. pis. I. -III. 
4 Compare Foote, op. cit. pi. I. 5 Compare Foote, pi. II. fig. 3. 6 Vide supra, p 41, note 2. 
