105—18 CRANIA OR RUMINANTS RROM THE INDIAN TERTIARIES. 
and the orbits are closely approximated ; the cranium of Bibos gaurus is hut slightly 
contracted in width between these two points, while that of Bibos frontalis is not 
contracted at all in the same place ; the orbits of the former species are non-salient, 
while those of the latter are considerably depressed below the plane of the f rentals. 
The nasals of both species are wider at their free distal extremities than at their 
infra-orbital angles, while those of Bibos frontalis are fm’ther distinguished by their 
extreme shortness : finally, the length of the facial portion of the cranium in both 
species is equal to that of the frontal portion. 
If now we compare together the occipital surfaces of the three crania, we shall 
find still more striking and marked differences between that of Bos namadicus and 
those of Bibos. Eigures of the occiput of Bos namadicus are given in the present 
memoir {Blate XVI, figs. 1, 3) ; and figures of the same region of the crania of 
Bibos gaurus and Bibos frontalis will be found in Mr. Hodgson’s paper on the 
genera of Indian cattle.’ 
Turning firstly to the occiput of Bibos frontalis, we find this surface of the 
skull divided into two distinct portions ; interiorly there is the proper occipital or 
infra-cristal smfface roughened for muscular attachments ; and superiorly the smooth 
parieto-frontal or supra-cristal surface situated between the bases of the horn-cores. 
At the junction of these surfaces the occiput is deeply indented from either side 
by the temporal fossae — so deeply that the intervening surface of the parietals is 
but very slightly, if at aU, wider than the interval between the external angles of 
the occipital condyles. These temporal fossae are wide, and a portion of their inner 
termination on the occipital surface is situated above the summit of the occipital 
crest ; while the latter is placed below the lower border of the base of the horn-cores. 
The interval between the external angles of the occipital condyles is precisely 
equal to that between the lower border of the foramen magnum and the summit of 
the occipital crest, and is equal to one-half the width of the widest part of the 
occipital smfface ; and, as stated above, is very nearly equal to the interval between 
the temporal fossae. Below the summit of the occipital crest there is a large shield- 
like protuberance for the attachment of the ligamentum nuchae. The intercornual 
ridge is wide and straight. 
The occiput of Bibos gaurus agrees in form and comparative measurements with 
that of the last species, with the exception that the intercornual ridge is produced 
forwards between the horns in a high arch, so that the vertical height of the sujjra- 
cristal portion of the occiput is greater than that of the infra-cristal portion. 
On the other hand, the occiput of Bos namadicus has a totally different form 
from either of the above. The temporal fossae make but very small indentations on 
to the occiput, and consequently this surface is not so distinctly divided into two 
portions. The indentations of the temporal fossae being so small, the summit of the 
occipital crest is placed considerably above them, and extends upwards bevond 
^ Journal of the Asiatic Society of Bengal, Vol. X, p. 470. 
