117—30 CEANIA OP RUMINANTS PROM THE INDIAN TERTIARIES. 
The orbit is remarkable not only for its position so much below the median line 
of the forehead, but for its very small diameter and nearly circular form ; its longer 
diameter is only 2* 6 inches, and the difference between the two diameters is *2 inch. 
In Bos namadicus the longer diameter of the orbit is 3T inches, and the difference 
between the two is A inch. In the much smaller cranium of Bibos gaurus the 
longer diameter of the orbit measures 2’7 inches. Prom the occiput being placed far 
beneath the overhanging frontals the temporal fossae are shorter than in Bos nama- 
dicus. The ovate section of the horn-cores is undoubtedly a character of Bibos, but, 
as noticed above, some forms of Bos namadicus have the same form of horn-cores, 
and there can be no doubt as to the genus of that species. 
Pinally, I regard this cranium as presenting characters considerably divergent 
from those of the type forms of Bos, but not so divergent as to afford valid grounds 
for placing it in a distinct sub-genus, as we find approximations to those diverg- 
ing characters in other species of Oxen, which undoubtedly belong to that restricted 
genus. 
In addition to the above specimen, there are portions of two horn-cores in the 
Indian Museum which belong to the same species. These specimens also were 
collected by Mr. Theobald in the Siwaliks. 
The interval between the tips of the horn-cores of this species could not have 
been less than nine feet, and when covered by the horn-sheaths their span must have 
been at least ten feet. Taking the interval between the tips of the horn-cores as 
nine feet, this would be equal to ten times the breadth of the cranium between the 
superior border of the orbits. In Bos namadicus the interval between the most 
distant parts of the horn-cores (rather below the tips) is only equal to four and a half 
times the width of the cranium between the orbits. In the European Bos 
primigenius, the interval between the tips of the horn-cores is slightly more than 
three and a half times the width of the cranium between the orbits. The large horns 
of Bubalus arni, figured in Plate I7l of the “ Ossemens PosslLes,” have an interval of 
rather less than seven feet between their tips, equal to seven and a half times the 
width of the skull between the orbits ; the interval between the horn-cores alone 
would be at least a foot less than the above. Specimens of Bubalus arni, I am 
informed, have been found reaching to twelve feet between the tips of the horns, but 
these are very rare. As it is not improbable that other specimens of the present 
species were larger than this specimen, and as I have made a small estimate for the 
distance between the horn-tips, individuals of this species were probably quite as 
large as any described recent or fossil form. The circumference of the base of the 
horn-core is rather less than in Bubalus palccindicus. The present species will some- 
what interfere with Cuvier’s definitions of the distinctions between the form of the 
frontals in the genera Bos, Bubalus, and Bison. In the sixth volume of the 
“ Ossemens Eossiles ” (p. 220) he writes, — Le front du bocuf est plat et meme un 
peu concave; celui de V aurochs est bombe, quoi-qu'un peu moins que dans le bufjle.^' 
The present skull is of course distinguished from those of the Aurochs by the excess 
