34 INMAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
skulls of R. javanicus in the Indian Museum show a double ‘crochet’ in the first 
true molar ; and we have seen a probable instance of the same in the last true 
molar of R. sivalensis . 
Second upper premolar. — The last specimen of the permanent upper dentition 
of this species, we have to consider, is the specimen represented in plate Y, figure 3. 
This tooth is also from Mr. Theobald’s Punjab collection : it is much worn down. 
Erom its general resemblance to the second (ante-penultimate) left upper premolar of 
11. javanicus , it is inferred to be probably the corresponding tooth of R. sivalensis. 
The tooth clearly exhibits the much smaller depth of the posterior as compared with 
the ‘ median valley’ ; the former being nearly obliterated, and the latter still very ' 
deep. The only points by which this specimen can be distinguished from the cor- 
responding tooth of the Javan rhinoceros are its larger size, and the somewhat 
greater development of the ‘ cingulum ’ on the internal surface. 
Upper milk-molars. — In figure 2 of plate YI are represented three upper milk- 
molar teeth of a rhinoceros, obtained by Mr. Theobald from the Siwaliks of the 
Punjab, and probably belonging to R. sivalensis. The specimens figured are from 
the left side of the skull, but the corresponding teeth of the opposite side were also 
found with them. With regard to the species to which these teeth should be re- 
ferred, it will be seen from what has been previously written that they do not 
belong to Acerotherium perimense ; it will be shown subsequently that they certain- 
ly do not belong to R. palceindicus ; while from the absence of a ‘ combing-plate ’ in 
the hindmost, they do not belong to R. platyrhi/nus, an inference confirmed by the 
absence hitherto of all remains of that species in the Punjab. There accordingly 
only remains R. sivalensis , to which they can be assigned; and we have, therefore, 
only to consider the serial position of these teeth. Erom the antero -posteriorly 
elongated form of the anterior tooth (mm. 2), it might at first sight be thought that 
the teeth are .the first three of the milk-molar series, but the complex form of the 
first tooth (having complete anterior and posterior ‘ colles ’), together with the form 
of the second tooth, seems to forbid this view. In respect to the latter point, it may 
be observed that there are no instances known to me in which the second upper 
mi lk-molar of a rhinoceros has the interior ‘costa’ approximated to the antero- 
external angle (as in the middle tooth, mm. 3 of our specimen) ; the position of this 
‘ costa ’ being central, or sub-central if distinctly developed at all. It seems, there- 
fore, that the teeth under consideration are (reckoning from left to right) respec- 
tively, the second, third, and fourth of the deciduous series. On this assumption 
the first milk-molar must have been an exceedingly small tooth, and was prob- 
ably shed in very early life. 1 In this respect, R. sivalensis agrees with R. java- 
nicus, which is distinguished from R. indicus by the smaller size of this tooth, and 
by the earlier time at which it is shed. 
The second milk-molar (mm. 2 in figure 2) is an irregularly-shaped tooth, 
1 A very minute undescribed tooth in the Indian Museum is not improbably the first upper milk-molar of this 
species. 
