38 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
nislied witli a lower jaw totally unlike that of the latter species, and nearly resem- 
bling the jaws of the bicorn living African or pleistocene European species. Again, 
no known unicorn species, either recent or fossil, has a mandible unprovided with in- 
cisors, like the one referred by Ealconer and Cautley to the unicorn R. sivalensis. 
Hence there is a very strong presumption indeed that the Siwalik lower jaw without 
incisors belonged to a bicorned species, while to R. sivalensis there belonged one of 
the two forms of tusked lower jaws referred by Ealconer and Cautley to the other two 
Siwalik species. This inference is supported by the fact that in the Punjab none of 
the numerous mandibles of fossil rhinoceroses collected by Mr. Theobald belong to 
the form referred to R. sivalensis, 1 while nearly all the upper molars (except 
those of Acerotherium ) belong to R. sivalensis, and none to R. platyrhinus. Ealconer’s 
determination would, therefore, drive us into the double dilemma of, firstly, referring 
to a species closely allied to the Javan rhinoceros, a form of jaw nearly resembling 
that of a bicorn species; and, secondly, of finding no lower jaws of a species in a 
district where its upper jaws and skulls are of comparatively common occurrence. I 
therefore conclude that Ealconer and Cautley’s determination of the lower jaw of 
R. sivalensis is probably incorrect. 
Erom this it will be clear that one of the forms of mandible referred by Ealconer 
and Cautley respectively to R. palceindieus and R. platyrhinus will probably 
belong to R. sivalensis. Now of these two, I find that the one referred to R.palce- 
indicus approaches most nearly in general form to the mandible of R. javanicus, and 
that this one appears to be the most common in the Punjab where R. sivalensis is 
the prevailing species. It is true, indeed, that in the presence of median incisors the 
mandible referred by Ealconer and Cautley to R. platyrhinus agrees more closely with 
the mandible of R. javanicus, but its general form is different, and it is by no means 
certain that small median incisors may not have been developed in the jaw I have 
provisionally assigned to R. sivalensis, and have been shed at an early period. 
There now comes the question as to which of the two remaining lower 
jaws should be assigned respectively to R. platyrhinus and R. palceindieus . The 
former species, as has been already stated, is a bicorn form, and, as will be shown 
subsequently, has upper molars formed on the complex Indian type. Now, the only 
species of rhinoceroses known to me, which are bicorn, and furnished with perma- 
nent lower incisors, are R. sumatrensis (?—R. lasiotis ) and R. schleiermacheri, 
and these have upper molars of the simple or Sumatran type. No bicorn species 
with teeth of the Indian type ever have permanent outer incisors, 2 though 
some species without incisors have molar teeth of the Sumatran or intermediate 
type ; e.g., R. bicornis, R. etruscus, R. leptorhinus (Owen), R. megarhinus, R. pachy- 
gnathus, R. tichorhinus. Einally, as already said, there is no known instance of an 
1 Although these specimens, with one exception, do not show the symphysis, many of them show the whole of the 
premolar dentition, which, in the form referred hy F. and C. to E, sivalensis, is placed directly on the symphysis ; the 
specimens therefore indicate a form with a produced symphysis. 
* According to M. Gaudry. \loc. cit. p. 52), E. pachygnathus and E. lejotorhinus sometimes develope very minute 
inenr incisors. 
