128—30 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
does also from R. megacephalum. The ‘lobes’ of the teeth are placed still more 
obliquely to the long axis of the jaw than in the latter species, while the median 
‘ costse ’ are much less developed, those of the second ‘ lobes 5 being almost obliterated. 
If a rod be placed on the inner surfaces of the last true molar, it will only rest on 
their posterior ‘ costse,’ while in R. megacephalum it will rest on the median ‘ costse ■ 
of the hind ‘ lobe,’ and the posterior ‘ costse ’ of the fore ‘ lobe ;’ in Sivatherium a 
similarly placed rod will rest on the median ‘ costse ’ of both ‘ lobes/ This shows 
that the teeth of the present specimen are further removed from the Sivatherium 
type than those of R. megacephalum. The last premolar is a very characteristic 
tooth, and is remarkable for the great proportionate development of its posterior 
* crescent ’ and ‘ lobe.’ The inner surface of the ‘ lobe ’ is fan-shaped, and nearly 
flat, the median ‘ costa ’ being very slightly developed, and the anterior ‘ costa ’ 
forming the front border of the tooth. In the last premolar of Sivatherium the 
median ‘ costa ’ is very largely developed, forming the most prominent part on the 
outer surface ; the inner surface of the ‘ lobe ’ itself is relatively taller and narrower, 
with straight er borders. In R. megacephalum the ‘ jobe ’ of the corresponding 
tooth is both narrower and higher than the tooth in question, and would alone be 
sufficient for the distinction of the two species. In the following table the dimen- 
sions of the specimen before us are compared with those of the lower jaws of Siva- 
therium and R. megacephalum : — 
H. megacephalum. 
H. grande. 
Sivathirium. 
Length of last premolar 
1-7 
Width „ 
il 
Height „ 
1-6 
1-4 
1-72 
Length of inner surface of anterior lobe of ditto 
1*05 
1-3 
• 1-4 
„ first true molar . . . . 
1-85 
1-98 
2-05 
Width „ 
1*3 
1-2 
1-55 
Length of second „ 
1-87 
■ 2 04 
2-15 
Width „ 
1’35 
1-23 
1-15 
Length of third 
2-64 
25 
2-95 
Width 
1-25 
1-3 
1-6 
Height „ 
1-7 
1-7 
2 0 (?) 
Length of four last teeth 
77 
Depth of jaw at first true molar . . , , 
2-52 
3-7 
3-45 
„ „ third „ .... 
3-3 
37 
4'7 
The differences in the form of the specimen indicated by the above dimensions, 
together with the differences in the structure of the teeth, render it pretty certain that 
it cannot be referred either to Sivatherium or to Ry daspitherium megacephalum. 
