SIWALIK RHINOCEROTIDAJ. 
11 
the species It. planidens and IU iravadicus must be removed from the list of Siwalik 
mammals. 
In figure 1 of plate XL of volume II of the second series of the “ Transactions 
of the Geological Society,” two teeth of the upper molar series of a rhinoceros were 
figured, without being specifically named, by the late Mr. Clift. These teeth belong 
to the present species, as was noticed in the first volume. 
This completes the list of previous notices of the species, and I, therefore, 
now proceed to describe the new specimens forming the subject of the present 
memoir. 
Cranium. — The cranium, of which two views are given on plate I of this volume, 
was obtained in the year 1878 by Mr. Theobald from the Siwaliks of the Punjab, 
and is the specimen referred to in the passage of the Xllth volume of the “ Records” 
already quoted. Before proceeding to describe the specimen, it will be well to 
mention the grounds on which it is identified with Acerotherium perimense of 
Palconer and Cautley. 1 The figured cranium contains a series of seven molar 
teeth, all much worn down, and thereby showing that the cranium belonged to a 
fully adult individual. These teeth being so much worn down and partly concealed 
by closely adhering matrix, are not calculated to afford a satisfactory figure, and 
accordingly the left upper molar series of a rhinoceros containing precisely similar, 
though less worn, teeth has been lithographed (pi. II) in order to illustrate the 
dentition of this species. In the figured series of molars, if the second tooth 
from the left, being the second premolar, be compared with the perfect upper 
premolar of Acerotherium perimense figured by Palconer and Cautley, 2 the 
two will be found to be identical in general characters, the only difference 
being that the c cingulum 5 is crenulated in the one specimen and simple in the 
other ; this, however, will subsequently be shown to be a variable character. On the 
similarity of these two teeth depends the identification of all the specimens treated 
of in this volume with Acerotherium perimense of Palconer and Cautley. This 
identification also fixes the serial position of Palconer’s specimen, which had hitherto 
been uncertain. Dismissing for a time the dentition, we may revert to the con- 
sideration and description of the cranium. The specimen is more perfect than is 
usually the case with the larger Siwalik fossils, but has still sustained considerable 
injuries. It lacks the extremity of the nasals and of the maxillae ; while the pre- 
maxillae are, of course, likewise wanting. Both zygomae have been broken away 
near their origin, and the processes of the squamosal region of the lower aspect 
have also disappeared. The teeth are a good deal battered, and the ridges bounding 
the temporal fossae have also suffered. Pressure has, moreover, somewhat interfered 
with the original symmetry of the skull, as is shown in figure 2. As before said, the 
teeth indicate that the cranium belonged to an aged animal — an inference confirmed 
by the total obliteration of all the cranial sutures. 
1 Here and subsequently I allude to tbe species as an Acerotherium. 
3 F. A. S., pi. LXXV, fig 15. In tbe description of this plate tbe number of this specimen is given wrongly as 
fig. 14. 
