96 
lleconh of the Geological Snrveg of India. 
[voL. XI. 
In the present notice I shall only refer to certain upper teeth of H. planidens, 
which are far more perfect than the specimens of njiper molars described at 
page 23 of “Molar Teeth and Other Remains of Mammalia,”and upon the 
evidence of which the species was founded; and also to a portion of the lower 
jaw of the same species. The new specimens incontestably prove the distinctness 
of the species. 
Of the two specimens of upper molars which I have selected for notice here, 
one is the penultimate tooth, and the other the last tooth, of the right side. 
Both teeth are quite complete and in a middle state of wear; they are of such 
a size that by this character alone they might be well distinguished from H. 
sivalensis, which is the only one of the Siwalik species of Bhinoceros with which 
they have any affinity. 
Both of the original specimens on which the species was founded lacked the 
external surface of the crown, the form of which has been therefore hitherto 
unknown. In the present specimens wo find that the dorsum or external sur¬ 
face is produced into a bold buttress at its antero-external angle, and that the 
rest of that surface is nearly flat; the presence of this buttress alone is sufficient 
to distingnish these teeth from those of B. platyrhm'us. 
The other characters of the penultimate tooth are similar to those of the 
previously-acquired specimens, and need no further notice here. The last tooth, 
allowing of course for its different form, agrees in general characters with the 
previous specimen; it is readily distinguished from the corresjDonding tooth of 
B. sivalensis by its vastly superior size, and by having a very wfide cingulum 
surrounding the outer and inner sides of the anterior collis, and which is con¬ 
tinued into the median valley to form a low and wide tubercle at the entrance, of 
which there is no representative in the coi'responding tooth of B. sivalensis; 
the tooth has a small crochet and a large antecrochet. 
The dimensions of these two teeth are compared below with the same 
dimensions of the coiTcsponding teeth of Bhinoceros sivalensis :— 
Fenuliimate molar. 
Length of anterior surface 
It. plant. 
In. 
. 3-20 
R. siva. 
In. 
2-70 
„ of internal surface 
. 2-45 
1-82 
„ of posterior surface 
. 2'60 
2-34 
„ of external surface 
. 3-40 
2-50 
Height of crown 
. 2'22 
2-10 
Last molar. 
Length of anterior surface 
. 320 
2'30 
„ of internal surface 
. 2-95 
1-90 
„ of posterior surface 
. 3-20 
2-35 
Height of crown 
. 305 
1-75 
The difference in size is, therefore, so great that from this alone there would 
be no doubt as to the specific distinctness of B. jjlanidons, which indeed seems 
to have been next in size to the largest specimens of B. platyrlimus, the largest 
of any species of Bhinoceros with which I am acquainted; the dorsum of the 
penultimate molar measuring upwards of four inches in length. 
‘ Palffiontologia Indica, Ser. X, Vol. I, pt. 2. 
