195—14 
SIWALIK AND NARBADA PROBOSCIDIA. 
tooth is the first lower true molar, while the greater height of the inner extremities 
of the transverse ridges (top border of figure) shows that the tooth belonged to the 
left ramus of the mandible. The tooth, therefore, corresponds to the second tooth 
(counting from the left) in the left ramus of the mandible of Binotherium penta- 
potamicB represented on Plate XXX ; the two teeth are almost in the same relative 
condition of wear, which will greatly facilitate our comparison. 
It will firstly be noticed that there is a very great difference in the matter of 
size alone in the two teeth, which, as far as it goes, would lead us to refer the two 
to distinct species. There are, however, more important points of differences in the 
form of the two teeth which I now proceed to consider. The larger tooth is dis- 
tinguished by having on its outer and hinder surfaces a very stout and thick 
cingulum, extending from the middle of the anterior ridge (left side of figure) 
along the outer and posterior surfaces ; (in the specimen this cingulum has been 
broken away on the posterior surface, hut the fractured surface shows its former 
extent) ; no trace of this cingulum is to he seen on the smaller tooth. Again 
in the smaller tooth, the worn surfaces of the first and second ridges are united by 
a longitudinal bridge of dentine, while in the second and third ridges the worn 
surfaces are still separated by the transverse valley. In the larger tooth, all three 
of the worn surfaces of the ridges are still separate, but it will he seen that the 
second transverse valley is as nearly obliterated as the first, and that consequently 
the worn surface of the third ridge would he united to that of the second, as soon 
as the latter would to that of the first. Pinally, the enamel of the larger tooth is 
very much thicker than that of the smaller. In the following table the dimensions 
of i\\e) ivViQ oi Binotherium pentapot amice and B. giganteum are 
compared vdth those of the corresponding new tooth : — 
New tooth. D. giganteum. D, pentapotami<B, 
Length of tooth . . . . 
3'9 
3-5 
2-35 
Width of first ridge . . . , 
2-5 
2-6 
1-8 
Ditto of second ditto 
25 
2-6 
1-8 
Ditto of third ditto 
2-4 
2'2 
1-7 
Thickness of enamel .... 
0-25 
0-19 
OTl 
These differences in size and 
form make it 
clear that the 
new 
tooth cannot 
belong to B. pentapotamicB. In 
the lower jaw 
of Binotherium indicum described 
by Dr. Palconer from Perim Island,^ the crowns of the molars have unfortunately 
all been broken off, and we eannot therefore compare the form of the first lower 
molar of that specimen with the Sind tooth. The bases of the molars, however, 
remain in the Perim Island jaw, and the dimensions of the first true molar, as given 
by Dr. Palconer,^ are as follows : Length 4 inches, width behind 2’8 inches. Now, 
we have already seen that the Sind tooth is slightly broken, and that therefore its 
length, where complete, must have been almost exactly equal to the Perim Island 
tooth ; the latter, however, is rather the wider of the two. As the Sind tooth 
* Palseontolo^ical Memoirs, loc, cit. 
- Ihid, p. 407. 
