SIWALIK AND NARBADA PROBOSCIDIA. 
9—190 
Prom a perusal of this table, it will be at once evident that the great difference 
in the matter of size alone, would be a sufficient distinction between DinotJierium 
pentapotami<E and D. itidicum., even if there were not differences in the form of the 
teeth themselves, which I shall point out when I come to the description of those 
of the latter species. The jaw of is less compressed than that of 
D. indicum ; if the jaw of the latter at the second premolar had the proportions of the 
former at the first true molar, it would have a width of 6T inches in place of only 5T 
inches, which is its real width. The less elliptical cross-section of the jaw of J). 
pentapotamicB is a character in which it approaches typical Mastodons. The specimens 
are too imcomplete to admit of any more elaborate comparison of the form of the jaw. 
With regard to D. giganteum, there is a closer resemblance in the matter of size 
between it and D. pentapotamics ; indeed, if we compare together the larger teeth 
of the latter, and the smaller teeth of the former, we might possibly find specimens 
which showed extremely little difference in the matter of size. This, however, 
would obviously be an unfair method of comparison, since we ought to compare 
together the large teeth of one species with the large teeth of the other, and mce versa. 
If such a comparison be made, it will always be found that the teeth of D. gigantetim 
are considerably larger than those of D. pentapotamice. Burther, the last lower true 
molar of the latter species has a much larger hind talon than the corresponding 
tooth of the larger European species, and there seems to be generally a greater 
teirdency to a development of the longitudinal bridge in the lovv^er molars of the former 
than in those of the latter sj)ecies. In my previous notice of the molars of the same 
species, I have pointed out certain distinctive characters of the upper molars, among 
the most important of which, is the complete blocking of the lower portion of the 
outer extremity of the transverse valley in the second upper true molar, a character 
which causes the structure of that tooth to approach to that of a premolar. These 
combined differences, together with those which I shall immediately show to occur 
in the form of the last upper premolar, confirm the conclusions previously arrived 
at, as to the specific distinctness of Dinotherium pentapotamice. 
It may be not out of place to notice that in teeth which are constructed on such 
an exceedingly simple plan as are those of Dinotherium, the variations in form 
which they are capable of undergoing must of necessity be extremely small, and 
there is consequently in most cases very great difficulty in deciding the specific 
identity or distinctness of isolated teeth, as has been remarkably illustrated in the 
case of the European forms of the genus. Any constant point of difference in the 
teeth, however small, must, I think, in consequence of this small amount of possible 
variation, always be regarded as of specific value. 
Last upper premolar . — The last tooth of the present species, which calls for 
notice here, is the specimen represented in fig. 3 of Plate XXXI, which is the last 
upper premolar of the left side, and which has not previously been described. The 
preceding or penultimate upper premolar of the right side has already been figured 
in Plate IX, fig. 1, of an earlier fasciculus of this volume.^ 
* “Molar Tc-etli and Other Ecinains of Mammalia." 
