SIWALIK REINOCEEOTIDJE. 
19 
f combing-plate’ and of a third or ‘accessory fossette’ on the well worn crown. 
The ‘cingulum’ is more developed in the premolars than in the true molars; while 
the reverse of this arrangement prevails with regard to the c buttress ’ and the 
c crochet.’ Although, as already said, agreeing in general plan with those of the 
Sumatran and Javan rhinoceros, the molars of the Perim species are at once broadly 
distinguished by the presence of the large ‘ cingulum.’ 
Comparisons with molar series of other species of Siwalik rhinoceros . — Although 
the cranium of the present species at once distinguishes it from the crania of all 
the other species of Siwalik rhinoceros, it may he well to point out how the teeth 
may he distinguished, as they are the remains most frequently met with in the 
fossil condition. Now that the two so-called species, B. planiclens and JR. ira- 
vadicus, are shown to be indentical with the present species, there only remains 
JR. platyrliinus, B. palceindicus , and JR. sivalensis for comparison. The upper molars 
of the first of these species 1 are formed on the type of JR. indicus , — that is, they 
have no external buttress, hut a * comhing-plate ’ and ‘ accessory fossette ’ on the 
■worn crown, and are, therefore, totally unlike those of the present species. The 
upper molars of JR. palceindicus 2, have a much less developed ‘buttress’ at the 
antero-external angle, a larger ‘ crochet ’ extending across the ‘ median valley,’ so 
as not unfrequently to cut off a third or ‘accessory fossette’ on the much- worn 
crown: the ‘cingulum’ and tubercle at the entrance of the ‘median valley’ so 
characteristic of the present species, are in general practically absent in JR. palce- 
indicus. The upper molar series of JR. sivalensis 3 approaches nearer in general 
plan of structure to that of the Perim hornless rhinoceros ; hut the teeth are at 
once distinguished by the absence of any trace of a * cingulum’ on the inner sur- 
face, or of any tubercle at the entrance to the ‘ median valley.’ The ‘crochet’ of 
the premolars, as will he noticed below, is, moreover, much more developed in 
JR. sivalensis. 
Resemblance to R. deccanensis. — In describing the second upper premolar 
subsequently referred to Acerotlierium perimense from Sind, hut which I was then 
unable to refer to that species, in the first volume of this series, 4 1 commented 
upon the resemblance which it presented to the premolars of Rhinoceros dec- 
canensis of Mr. Poote, 5 and consequently inferred that the latter species showed 
indications of affinity with the older forms of the family, — a very noticeable fact 
in a pleistocene species. The subsequently-acquired specimens have fully borne 
out the resemblance between the molars of the two forms. If the figures of the 
upper premolars given by Mr. Poote he compared with- those of A. perimense 
given in this volume, it will be apparent that there is a most marked resemblance 
between them. 6 The common features are the large ‘ cingulum,’ and the approxi- 
1 Infra, pi. VIII. 2 PL VI; fig. 1. F. A. S., pi. LXX, fig. 1. 3 Supra, Vol. I, pi. V, fig. 5. 
4 Pp. 44 — 5. 8 Supra, Vol, I, p. I, et. seq., pi. I. 
6 In Mr. Foote’s specimen the first premolar is wanting, and therefore the first three teeth in that figure cor- 
respond to the second, third, and fourth teeth in m3" figure. 
