40 
INDIAN TERTIARY AND POST-TERTIARY YERTEBRATA. 
The specimen of the symphysis figured in the “Eauna Antiqua Sivalensis,” 
already referred to, is somewhat wider ; this additional width seems in great part 
due to pressure ; there are, however, analogous differences in the width of the sym- 
physis of the living species. 
Var. gajensis, Nobis. 
Specimens . — The next specimens for consideration are the hinder portion of a 
skull and the upper molar of a rhinoceros, obtained by Mr. Eedden in Sind from 
a group of rocks known as the Gaj beds (plate Y, fig. 7 ; plate YII, fig 1). The 
specimens in question are those on which rests the statement given in Mr. W. T. 
Blanford’s “Geology of Western Sind”, 1 that 11. sivalensis occurs in the Gaj 
beds, and is the only mammal found in them. The age of these beds is given in 
the same memoir as being probably miocene, with a possibility of being the upper 
part of that period. This fossil is accordingly in all probability from a lower horizon 
than any of the other mammals from Sind and the Siwaliks, and its specific deter- 
mination is therefore a matter of very considerable interest. In the course of the 
following description, there will be pointed out certain peculiarities in which the 
remains from the Gaj beds differ from the corresponding remains of type specimens 
of U. sivalensis ; but it will also be shown that in regard to the teeth there is a 
transition from the type Siwalik forms to the Gaj form, and I have, therefore, come 
to the conclusion that it will be best to consider, at all events provisionally, the Gaj 
fossil as a variety of U. sivalensis, for which I propose the name gajensis ; at the 
same time indicating the possibility of its specific distinctness. 
Skull . — The fragment of the skull unfortunately alone remaining consists of 
the hinder half only (pi. YII, fig 1) ; this, however, is fairly perfect. This skull 
was found in company with two molars, one of which is figured in plate Y, fig. 7, 
and was probably intact before it was extracted from its bed. The condition of 
the molars proves it to belong to an animal which had not attained its full dimen- 
sions. If the figure of the Gaj skull be compared with the corresponding part in 
the adult skulls of 11. sivalensis, figured by Messrs. Baker and Durand, 3 by Ealconer 
and Cautley, 3 and in this volume, it will be seen that the supra-occipital region 
in the former is not produced into such a high angular peak as in those specimens, 
while the Gaj skull is also of considerably smaller dimensions. We have, however, 
seen reason to believe that the latter belongs to an immature individual, and it is, 
therefore, not in a condition to afford well-marked specific characters. Seeing that 
in the large living unicorn Indian rhinoceros there is a very considerable difference 
n the relative development of the supra-occipital region according to age, 4 it is 
1 Mem. Geol. Surv. Ind., vol. XVII, p. 57. s loc . cit., pi. V, fig. 3. 3 ‘ F. A. S.’ pi. LXXIII, fig. 2a. 
4 The non-development of the occipital region at an early age is well exhibited in a young skull of It. indicus 
figured by Dr. Gray (“ Hand-list of Edentate, Thick-skinned, and Ruminant Mammals in the British Museum,” 
pi. XIV). A good figure of an adult skull is given in De Blain ville’s- “ Osteographie.” 
