38— i INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
Tijincal crania . — The cranium is in the British Museum and is figured in 
plate LIX., figs. 1, la, lb of the 
“ F.A.S.,” and is also represented 
in the accompanying woodcut 
(fig. 1). It has lost the canines^ ; 
but shows the alveoli of three 
sub-equal incisors on either side. 
The cheek-teeth are much worn, 
ni. 1 being almost obliterated : 
the true molars are broader than 
long. An almost identical skull 
represented in figs. 2, 2a of the 
same plate shows the base of the 
canines, which are readily dis- 
tinguished from those of 11. 
amphihim by the much deeper 
channelling of their posterior 
surface.^ The same specimen 
shoAVS that pni. 1 , as in the existing 
species, was separated by a considerable interval from pm. 2. In both skulls m. 3 is 
placed a considerable distance in advance of the posterior border of the palate ; in 
the first s]3ecimen this tooth does not extend behind the posterior border of the 
anterior zygomatic root ; but it does so to a small extent in the second. Precisely 
similar dental characters are exhibited by tAVO other crania in the British Museum 
(Nos. 16,380 and 40,889): the dentition of the latter is in excellent preservation, 
and exhibits the large inner cingulum, Avhich appears characteristic of this form. 
According to Falconer and Cautley’s description, the type skull differs from H. 
amplnhius in the less jDrominent orbit ; the longer post-orbital portion ; the shorter 
and dee 2 Der jn'e-orbital constriction ; the more concave frontals ; the higher occpDital 
surface and crest ; the larger lachrymal ; the shorter diastema, and the more curved 
line of the cheek-teeth. The Avhole skull indicates an animal rather smaller than 
II. ampliibius. The dimensions of the tvqie S 2 )ecimcn are given in Falconer and 
Cautley’s memoir. 
Aberrant crania . — In plate LIX., figs. 3, 3a of the “ F.A.S.” there is figured the 
cranium of another SiAvalik hipjooiootanms in the British Museum, Avhich differs 
considerably from either of those described above : there is another jjrecisely 
similar specimen in the same collection (No. 17,469), in Avhich m. 3 is not fully 
jDi’otruded, and mnn 4 has not been shed. The figured sijecimen has lost the extremity 
of the muzzle, and a considerable jDortion of both zygomatic arches, but is otherwise 
fairly jDerfect. The Avhole of the four premolars are present ; and as m. 3 is fully 
ju'otruded the cranium evidently belonged to an adult individual. These two crania 
1 These are restored in the woodcut. 2 Compare “ F.A.S. pi. LXII. 
Fig. 1. Hippopotamtis sivalensis, F. and C.: a, palatal view of type 
cranium, with the teeth much worn, i; b, third right upper true 
molar in an early stage of wear, J ; c, upper view of anterior portion 
of mandibular symphysis, A. All the specimens are in the British 
Museum ; and came from the Siwaliks. 
