12 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
If the skull be compared with that of one of any of the living species of rhinoceros* 
it is firstly remarkable for its gigantic size. The next point that strikes the observer 
is the great width and flatness of the fronto-parietal region, which forms a nearly 
smooth triangular surface, with its base below (pi. I, fig. 2). The great width of 
this surface in the neighbourhood of the occipital crest is especially notable. Some 
distance behind the orbit, there occurs on this surface a small median oval-shaped 
elevation, succeeded by a slight depression. It has occurred to me as just possible 
that this elevation may have carried a rudiment of a posterior horn. The profile 
is nearly straight as far as the fronto-nasal suture, where there occurs a sharp bend, 
the planes of the nasals and frontals forming an obtuse angle with each other. 
The portion of the nasals remaining shows that these bones are transversely arched 
their sides being situated almost at right angles to their upper surface : when com- 
plete they must have been short, straight, and pointed. They are perfectly smooth 
superiorly, showing no trace of the roughened and longitudinally-arched form so 
characteristic of the living forms of rhinoceros. The form and condition of these 
bones also shows that the animal had no trace of any anterior horn, and the 
species is accordingly referred to the genus Acerotherium , as defined above. The 
orbit is of great size, and the vertical thickness of the skull in the region of the 
orbit is also a noticeable point. There do not appear to be any other points calling 
for especial notice in the general form of the skull. Erom the obliteration of the 
sutures and the somewhat battered condition of the specimen, the relations of the 
component bones cannot be determined : this renders it impossible to say whether 
the bones surrounding the external auditory meatus corresponded to the type of 
B. indicus and B. javanicus , or to that of B. sumatrensis and the African rhino- 
ceroses. 
Dimensions of cranium. — In the following table, the dimensions of the figured 
cranium are given in the first column, while in the second are given such of the 
corresponding dimensions of the original skull of the European Acerotherium inci- 
sivum as occur in Kaup’s description; 1 the original dimensions were given by 
Kaup in millimetres, but have here been converted into inches and tenths for con- 
venience of comparison : — 
Length from occiput to tip of nasals 19'0 (broken) 19'6 
Height of occiput from base of foramen magnum to crest . . . 10 - 0 8*6 
Greatest width of occiput 12 - 0 
Breadth at postorbital process of frontals . . . . . 10*5 6'8 
Interval between anterior angle of orbit and auditory fissure . . 13‘2 9'5 
„ „ „ extremities of zygomae .... 12'5 
Vertical diameter of orbit 3'7 
Breadth of base of nasals 4 0 
Length of seven molars 14'6 lO’O 
Interval between inner surfaces of the first of the molar series . . 3‘0 3'3 
„ „ „ „ ,, last „ 4*4 3*3 
Long diameter of occipital condyle 3 - 2 
1 “ Ossements Fossiles d. Mus. d, Darmstadt,” pt. Ill, p. 36. Darmstadt, 1834. 
