SIWALIK RHINOCEROTUm 
13 
Comparison with A. incisimm.-— From the foregoing table of measurements 
it will be apparent that the cranium of A. perimense is of considerably larger size 
than that of A. incisimm, and that the two crania differ in the relative inclination 
of the molar series. For the purpose of making a better comparison with Kaup’s 
figure of the skull of the latter species, 1 a reduced and restored figure of the skull 
of the Indian species is given in figure 1 of plate IX. On comparing these two 
figures, it will be observed that there is a very considerable difference in the profiles 
of the two skulls. The nasals of the Indian specimen are much thicker at the 
base, and, as far as can be inferred from the portion remaining, shorter and more 
wedge-shaped laterally, than those of the European form. The orbit in the former 
is more closely approximated to the median plane of the frontals than in the latter, 
and there is consequently a greater depth from the dental border of the orbit to 
the teeth. The temporal fossa is wider and shorter in the Indian than in the Euro- 
pean form, in consequence of which the distance from the anterior border of the 
orbit to the occipital crest is proportionately greater in the latter. Other minor 
differences might be indicated, but the above-mentioned, taken together with the 
great difference in the form of the teeth, which will be subsequently described, 
show that the two forms are markedly distinct. 
Other European species. — There is still considerable doubt how many species 
of fossil European rhinoceroses should be referred to the genus Acerotherium. 
The late Professor J. E. Brandt, in his synopsis of the living and fossil species of 
rhinoceroses and their allies, 2 only admits two European species, in addition to 
A. incisimm , which are provisionally referred to the same genus. Of one of 
these, — A. golctfussi, — the cranium is, I believe, still unknown; while of the other, 
A. minutum, the cranium has been figured by Kaup, 3 and, under the name of 
Rhinoceros pleuroceros, by Duvernoy. 4 The latter figure shows that the skull is of 
much smaller size than our Indian specimen, and that the nasals are much longer, 
more highly arched, and not impossibly bore a very minute anterior horn. There 
appears to be some doubt whether Rhinoceros aurelianensis (Nouel of the Euro- 
pean miocene should not be referred to Acerotherium : Professor Gaudry, 5 however, 
thinks it was probably furnished w r ith a small horn. 6 The nasals are more developed, 
and the profile of the skull less concave than in A . perimense. According to 
M. H. Eilhol, 7 Acerotherium ( Rhinoceros ) lemanense and 4. croizeti are charac- 
terised by a peculiarity in the molars, w r hich* will be alluded to below : the 
latter is further distinguished from the present species by its greatly inferior’ 
dimensions. 
1 Loc. cit , pi. X, fig 2. 4 “ Mem. d. l’Akad. Imp. d. Sci. d. S. Pet.,” Ser. 7, Vol. XXVI, pt. IV. 
3 “ Beitrage zur naher Kennt. d. urwelt. Sauget.,” 1854, pt. 1, pi. VIII. 
4 “Arch. d. Mus. d’Hist. Nat.,” Vol. VII, pi. I, fig. 2a. 
* “ Les Enchainements da Monde Animal, etc.” p. 18, fig. 39. 
6 Professor Cope (loc. cit., p*229) refers this species to the group Ceratorhinus : it is very difficult to see on what 
grounds this determination is made. 
7 “Ann. d. Sci. Geol.,” Vol. XI, pp. 78-79. 
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