197—16 
SIWALIK AND NAEBADA PEOBOSCIDIA. 
question but that they belong to distinct species. In the following table the 
corresponding dimensions of the two specimens are compared together : — 
Z). pentapotamiee. B. sindiense. 
Length of second molar 2'4 2 3 
Width of ditto 2’15 1’55 
Length of third molar 2’9 2-5 
Width of ditto 2'25 1’9 
Depth of jaw at second molar 5 3 3'1 
Ditto at third molar S'S 3‘3 
Width of jaw at second molar 3'4 2'9 
Ditto at third molar 41 3’5 
The great difference in the shape of the two jaws will be gathered from a 
perusal of the foregoing table. The lower jaw of D. jpentapotamice is laterally 
compressed, though, as before said, to a somewhat less extent than that of some other 
species, and its vertical diameter is consequently very much greater than its trans- 
verse diameter. In D. sindiense, on the other hand, the lower jaw is nearly cylin- 
drical, and at the last true molar the transverse diameter is greater than the vertical 
diameter. Whereas the lower jaw of penta'potamicB on its outer side descends 
vertically down from the teeth, that of D. sindiense is expanded into a distinct ledge 
below the roots of the molars. 
It is unfortunate that the molars of J). sindiense are in such a battered con- 
dition, so as to preclude any exact comparison with those of D. pentapotamiee, but 
the differences in the size and form of the two jaws are amply sufficient to afford 
grounds of specific distinction. In its cylindrical form, indeed, the lower jaw of 
Dinotherium sindiense seems to differ from the jaws of all other known species 
of the genus : from its sub-circular cross-section and generally slender form, I think 
it not improbable that this species of Dinotherium was unprovided with a long 
deflected symphysis and mandibular incisors. In all other species of Dinotherium 
the mandible is laterally compressed to offer more resistance to the enormous 
weight of the symphysis and tusks, and in all Mastodons with a long heavy symphysis 
and mandibular tusks {M, angustidens, M. longirostris, M. pandionis), the rami of 
the mandible are similarly compressed. If this suggestion should turn out to be 
true, it may be necessary to form a new genus for D. sindiense. In its sub-cylin- 
drical mandible this species shows affinity to the Mastodons with short mandibular 
symphyses. 
Family II—FLFFMAFTIDM. 
Prohosciuia in which there are never more than three teeth in use at the same 
time, and in which the number of ridges in the second true molar is either equal to, 
or greater than, the number in the preceding tooth, 
