SIWALIK RHIN OCEROTIDiE. 
23 
Upper milk-molars. — In figure 2 of plate III of this volume are drawn two 
upper molars of a rhinoceros, collected by Mr. Theobald in the Siwaliks, near the 
village of Asnot, in the Punjab. These teeth are implanted in a fragment of the left 
maxilla, which also shows the bases of the crowns of other teeth on either side of 
the two now remaining. Below the broken crown of the tooth on the right side of 
the figure, there is seen in the jaw the germ of another tooth, which would have 
replaced vertically the tooth above it. The presence of this germ-tooth in the jaw 
proves that the tooth above it, and all the teeth in advance of it, must belong to 
the milk -molar series ; consequently, the two figured teeth, as they are in advance 
of the tooth above the germ, and as they again had another tooth in advance of 
them, must be the second and third upper milk-molars of a rhinoceros, and it now 
only remains to consider to what species they belong. Of the three species of 
Siwalik rhinoceros besides the present, the milk-molars of R. palceindicus are known 
with tolerable certainty, and will be noticed below. Milk-molars of two other 
types are also known, and, as will be seen below, are referred with a fair amount of 
probability, respectively, to R. sivalensis and R. platyrhinus. There now only 
remains A. perimense, to which the specimens may be referred, and they have 
accordingly been provisionally so assigned. This identification is rendered the more 
probable for the following reasons ; firstly, the figured specimens come from a dis- 
trict of the Punjab where the remains of A. perimense are of extremely common 
occurrence ; secondly, they are of relatively large size, and, therefore, accord well 
with the permanent teeth of that species ; and, thirdly, they belong to the same 
species as two upper milk-molars from Burma, where only one species of fossil 
rhinoceros 1 is yet known to have existed. The latter teeth have already been figured 
in plate V, figure 4 of the first volume of this work, and were originally described 
on pages 45 and 46 as premolars, but not specifically determined. Subsequently, 
in the preface to the same volume (p. xiii), it was shown that these teeth 
were milk-molars, and that they might very probably belong to R. iravadicus. 
Since that species has been shown to be the same as Acerotherium perimense , 
the original inference with regard to the milk-molars would refer them to the 
latter species. 
Description. — Reverting to the specimens figured in this volume, we find that 
the second milk-molar ( left of figure) has been broken at its antero-external angle, 
but is otherwise complete ; while the third milk-molar is complete, though slightly 
obscured by matrix posteriorly. Both teeth are about half worn down. In the 
smaller tooth, the anterior ‘ collis ’ is smaller than the posterior ; the reverse being the 
case in the larger. The ‘ dorsum ’ of the smaller tooth shows that it carried, when 
complete, a single median and vertical ridge or ‘costa’ ; the corresponding surface of 
1 On page 16 of the first volume of this series, it is stated by Mr. Foote that there were probably three species of 
fossil Burmese rhinoceros, and in support of this he cites three specimens. The first of these are some upper premolars 
figured hy Clift, which correspond to the already described premolars of A. perimense. The second specimen is one of 
those- on which B. iravadicus was founded, which is now shown to be the same as A. perimense. The third is the jaw 
containing the two associated upper milk-molars noticed above, which also seem to belong - to the same species. 
