CRANIA OR RUMINANTS RROM THE INDIAN TERTIARIES. 17—104 
crest forms an unbroken regular curve ; its summit does not extend upwards to 
the middle of the base of the horn-cores, and consequently the supra-cristal portion 
of the occiput is of considerable height ; moreover, the latter portion projects 
backwards so as to overhang the plane of the infra-cristal portion of the occiput, 
and the plane of the whole occiput is consequently concave from above downwards. 
The ligamentum nuchse seems to have been inserted on a fiat smTace and not to a 
tubercle ; the paroccipital processes are broad and rounded, and the surface for the 
digastric muscle is narrow. The interval between the external angles of the occi- 
pital condyles is only slightly less than the interval between the inferior border of 
the foramen magnum and the occipital crest, the same interval is greater than half 
the width of the occiput measured through the foramen magnum, and is equal to 
two-thirds of the length of the interval between the extremities of the temporal 
fossse ; finally, the intercornual crest is often arcuated. 
The cranium of Bos namacUcm therefore difiiers from the cranium of Bos 
primigenius in the following points : the short premaxillse, which do not reach the 
nasals; the low position of the occipital crest relatively to the horn-cores, the 
arcuated intercornual ridge, the intrusion of the temporal fossae on to the occiput, 
the concave plane of the latter, and the regular curve of the occipital crest ; in 
almost all these points, in which the cranium of Bos namadicus differs from that of 
Bos primigenius, it approaches to the crania of the genus Bibos. 
The peculiar forward curve of the horn-cores of this species, as is well shorni 
in the profile view, presents considerable resemblance to the curve of the horn- cores 
of the yak j this, however, cannot be taken as of any importance in showing kinship 
between the two animals, as the forms of the crania of the two are so entirely 
different. 
We have now to consider in what manner the cranium of the present species 
differs from those of the two Indian species of Bibos. If we refer to the table of 
frontal measurements given below, it will be found that the antero-posterior 
diameter of the forehead of this species exceeds the transverse diameter by one and 
a half inches, whereas in the forehead of Bibos the transverse diameter is the longer 
of the two. 
In typical crania of this species the transverse section of the horn-core is either 
circular or approximately circular ; and the horn-cores are placed on the highest 
ridge of the skull, which is situated immediately above the proper occipital surface ; 
the base of the horn-core is separated by a long interval from the orbit ; and the skull 
between these two points is considerably contracted in width. The length of the 
frontal portion of the cranium considerably exceeds that of the facial portion, while 
the orbits are salient and placed on a level with the frontals, and the nasals are long 
and widest at their infra-orbital angle. 
On the other hand, in the genus Bibos the horns of the males are laterally 
compressed, and their uppermost border is concave (the same border of the horn- 
cores of B. namadicus being convex close to the skull) : the bases of the horn-cores 
