14 
FAUNA OF THE INDIAN FLUVIATILE DEPOSITS. 
Ell. Sondaicus. 
Eh. Sumatranus. 
making sucli an estimate. Many other minor but well marked differences might 
be adduced, but the above seem sufficient. 
From nil. Sondaicus Bh. Bencanensis is separated by the character of its 
incisors, which are very good-sized in the former. In 
Sondaicus the guard is only very moderately developed 
in the premolars, while the teeth are much less high crowned and show relatively 
much shallower valleys and very tumid outer walls instead of nearly flat ones like 
those of Bh. Beccanensis. 
In Bh. Sumatranus we find large strong incisors, a very slight development 
of the guard in the premolars, and a totally different 
form of the auditory fossa of the squamosal bone, 
whereby to distinguish it specifically from the Deccan species. In Sumatranus, 
owing to the very great curvature of the post-glenoid process, the apex of the fossa 
lies far behind the opening of the meatus auditorius, whereas in Beccanensis it is 
very nearly vertically over it. The posterior edges of the mandible are deeply 
notched below the condyle in Sumatranus. The zygoma also is much stouter, more 
cmwed in the vertical plane, and shows a crescent-shaped excavation on its upper 
edge just behind the post-orbital angle — all characters absent from Bh. Beccanensis. 
The difference between Bh. Beccanensis and Bh. nasalis. Gray, consists in the 
possession by the latter species of good-sized incisors and 
a persistent first premolar. In nasalis the guard is but 
very slightly developed, and the rami are very much slighter than in Beccanensis. 
In Bh. Floiceri, Gray, the teeth are decidedly less tall-crowned than in Bh. 
Beccanensis. Premolar 1 is persistent instead of deci- 
duous, and the molar series is characterized by a very 
prominent development of the second costa ( ^ 2 ) of the outer wall. The zygoma 
also is much more arched laterally than in the Deccan species, which was a con- 
siderably larger animal than Bh. Moioeri. 
A comparison of Rh. Beccanensis with Bh. niger. Gray, shows that the latter 
has an extended mandibular symphysis, longer in 
proportion than that of the former, which terminates in 
a narrow incisive edge not furnished with teeth and not showing any signs of 
alveoli. Bh. Beccanensis shows several small cavities on the incisive border, sup- 
posed to be alveoli, from which the existence of rudimentary (though very likely 
deciduous) incisors must be inferred. The mandible of Bh. niger is much slighter, 
and the ascent of the ramus does not begin till well behind molar 3, whereas in Bh. 
Beccanensis it commences at the middle of the outer wall of molar 3. The ascending 
portion of the ramus of Bh. niger is also much slighter, and is incurved along the 
posterior edge below the condyle instead of straight as in Beccanensis. The 
zygoma shows a well marked lunate excavation on its upper edge not found in 
my new species. The meatus auditorius of Bh. niger is narrow and leans slightly 
forward, and is altogether unlike that of Bh. Beccanensis. 
Eh. nasalis. 
Rh. Floweri. 
Eh. niffer. 
