SIWALIK RHINOCEROTIDiE. 
53 
(p. 46), it was considered that it belonged to the premolar series, and it was hence 
concluded that it could not belong to R. platyrhinus , though it was shown that it 
presented the general characters of the true molars of that species. In the subse- 
quently issued preface to the first volume (p. xii), it was stated that this tooth was 
probably an anterior milk-molar of R. platyrhinus. A comparison of the figure 
with that of the teeth considered to be the milk- molars of that species will show 
that the single tooth agrees so closely with the second milk-molar that the two are 
doubtless homologous. The detached tooth is somewhat more produced antero-poste- 
riorly, but this cannot be considered as a character of more than individual value. 
Besides the last specimen, there is another specimen of a right upper milk-molar of 
a Siwalik rhinoceros in the Indian Museum, numbered S. 854 in Dr. Ealconer’s 
“ Catalogue of the Eossil Yertebrata of the Asiatic Society of Bengal.” This tooth 
agrees precisely with the third upper milk-molar (mm. 3) referred above to R. platy- 
rhinus , and must be the corresponding tooth of the opposite side. 
The dimensions of the four above-described milk-molars are as follows ; the 
dimensions of the casts of the British Museum specimens are given in the first 
column and those of the Indian Museum specimens in the second : — 
Length of second milk-molar . 1'7 . 1*6 
Width of „ „ „ . 1-4 1-4 
Length of third „ „ . 2‘0 1*94 
Width of „ „ „ . 2-0 1-91 
A comparison of these milk-molars with the corresponding teeth of the Euro- 
pean R. tichorhinus shows that the latter are distinguished by the presence of a dis- 
tinct ‘ pass 5 at the entrance to the ‘ median valley. 5 In this respect, therefore, the 
milk-molars of the two species agree with the true molars. 
Mandible . — The reasons for the provisional assignation of the mandible re- 
presented in figure 6 of plate LXXIY of the “ Eauna Antiqua Sivalensis ” under 
the name of R. sivalensis to the present species have already been given at length 
when treating of that species. 
The specimen as figured shows that the premolars extend up to the extremity 
of the part of the symphysis remaining, thereby giving the jaw very much the 
appearance of the mandibles of the African rhinoceroses. Erom the description of 
the plate, however, it may be inferred that the extremity of the symphysis has been 
broken off. Now, since we have already seen that the premaxillse of R. 'platyrhinus 
(in common with other Siwalik rhinoceroses) are well developed, I infer that the 
extremity of the mandible, when complete, was produced into a e spatula ’ beyond 
the premolars. Its original form was probably very like that of the mandible of 
the extinct European R. etruscus, 1 in which the anterior premolars are situated 
above the hinder part of the symphysis, and still have the spatulate portion in ad- 
vance of them. 
The specimen under consideration has lost the hinder portion of each ramus, 
1 “ Pal. Mem.,” Vol. II, pi. XXVII, fig. 3. 
o 
