MOLAR TEETH AND OTHER REMAINS OE MAMMALIA. 
31 
The dimensions of this specimen are — 
In. 
Anterior side. . . 
... 1-6 
Internal side... 
... 1-2 
External side 
... 1-6 
Posterior side 
... 1-7 
The lower molar figured in Plate 6, Eigure 7, is the antepenultimate tooth of 
a right mandible of a ’Rhinoceros from the Siwaliks, different from either of the 
three species of Ealconer. The specimen is in the collection of the Asiatic Society 
of Bengal ; there is also a detached portion of the same jaw containing the ultimate 
and penultimate teeth. The state of wear of this specimen is about the same as that 
of the last. Dr. Ealconer described this specimen as a milk molar, but he was, ap- 
parently, not aware that the next specimen in the catalogue belonged to this jaw. The 
tooth differs from the lower molars of any other species of Rhinoceros that we have 
seen, in the great relative size of the anterior collis {left of figure) which projects 
on the inner side in advance of the other colles. The anterior valley is large 
{left of figure) and of equal depth with the posterior {right of figure) ; on the 
worn-crown, therefore, the two valleys would remain, as notches on the inner side, 
for an equal period. The outer end of the anterior valley is rounded, and that 
of the posterior valley angulated ; the three worn dentine surfaces leading from 
the colles are nearly parallel, and placed obliquely to the longer anis of the 
tooth. 
On the anterior side of the tooth, the enamel of the crown shows a transverse 
section of two vertical costae ; these extend downwards to the base of the crown. 
On the anterior side of the median collis {middle of figure) there is a slight infolding 
of the enamel, and other crenulations may be seen on the outer wall. The posterior 
collis {right of figure) has its inner extremity expanded antero-posteriorly. In 
the middle of the inner border of the posterior valley {right of figure) there is 
a simple ovate tubercle detached from the posterior collis. There is no cingulum 
on the inner face of the tooth ; but a small, though distinct cingulum, occurs both 
on the anterior and posterior surface. The length of this tooth is 1*8 inches, and 
the width *9 inch. 
The succeeding tooth of this jaw {A. S. R. No. is unworn; it has the 
same form and the same crenulated enamel as the figured specimen ; the tubercle 
in the posterior valley is, however, considerably larger. The length of the tooth 
is 2 inches. 
The large anterior collis, the crenulated enamel, and the tubercle in the 
posterior valley, sufficiently distinguish the tooth from the figured Siwalik speci- 
mens ; but it would be somewhat unsatisfactory to found a new species on a lower 
molar only. 
The specimen drawn in Plate 6, Eigure 3, is another right lower molar of a 
species of Rhinoceros, different from any of those described above. The tooth is 
( ) 
