47 
PART 1.] Lt/cleJcJcer : Further Notices of Siwalik Mammalia. 
jection, having no resemblance to the broad and curved bones which occur in 
the other species. The transverse diameter of the base of these bones in the 
new cranium is only 3'3 inches, whereas in the smaller crania of B. sivalensis 
and B. palceindious it is 5 and about 4-8 inches respectively, and in the largo 
B. platijrMnus is upwards of 6’5 inches. Again, the base of the nasals in the 
new cranium is perfectly smooth even on the upper surface, shewing that 
there was no nasal horn, such as exists in the other species; the frontals are 
also perfectly smooth, and shew no signs of having ever carried a horn. 
The cranium, therefore, is truly that of an Aoerotlierium, and as such quite 
distinct from the other Siwalik species of Rhinoceros. 
Together with this cranium, Mr. Theobald has sent the less worn upper 
dentition of another individual of the same species, which is in a better state for 
comparison than the more worn dentition of the cranium. The antepenultimate 
upper premolar in both these specimens agrees exactly with the corresponding 
tooth represented in fig. 15 of plate 75 of the “ Fauna Antiqua Sivalensis,” 
which is the type of A. perimense ; the true molars in Mr. Theobald’s specimens 
also agree with the fragmentary molars of the same species represented on the 
same plate; the new cranium may, therefore, be .safely referred to A. perimense. 
This being so, the complete dentition of this species now enables me to cor¬ 
rect a very serious error into which I had fallen, and through which I had been 
led to form a new species of Siwalik Rhinoceros, (B. planidens), though working 
with imperfect materials. 
If we turn to figures 7 and 8 of the second part of the tenth series of the 
“ Palseontologia Indica,” it will be found that I figured two imperfect upper 
molars of a Rhinoceros, wRich I considered to be different from the corresponding 
teeth of any other species, and which I accordingly referred to a new species 
under the name of B. planidens. Subsequently several complete upper molars, 
and a considerable portion of a mandible, together with an upper incisor, all of 
large size, were obtained by Mr. Theobald, and were referred to under the same 
specific name at page 96 of the last volume of the “ Records.” 
Row, the true molars in Mr. Theobald’s two latest specimens agree precisely 
with the above-mentioned upper molars, and clearly belong to the same species. 
It is therefore clear that the new species B. planidens must be merged in 
A. perimense. 
In figure 5 of Plate VI of the same volume of the “ Palseontologia Indica” 
I figured two teeth of A. perimense, which I considered to be the last premolar 
and the first true molar, because, as will be seen by the figure, the second of 
these two teeth is the most worn. Considering this latter tooth to be a true 
molar, it was apparent that the true molar referred to B. planulens could not 
belong to A. perimense. A comparison of the two teeth in que.stion with the 
dentition of Mr. Theobald’s specimens show's, however, that these teeth are really 
the first and second premolars, and that their relative rate of wear must be an 
abnormality I may add that I ought to have known that these two teeth must 
