SIWALIK CROCODILIA, LACERTILIA, AND OPHIDIA. 
15—223 
much more sudden fall in advance of the orbits towards the rostrum. In adult 
crania of the existing species the width of the bar dividing the supratemporal fossae 
is about one-fifth the interorbital width/ whereas in the present specimen the former 
diameter is nearly equal to one-half the latter. On the palatal aspect the specimen 
apparently agrees very closely with G. gangeticus. 
That the specimen under consideration is specifically distinct from the existing 
gharial there can be no reasonable doubt ; and since it accords well in relative size 
with the cranial rostrum described above, and also in the sudden descent in advance 
of the orbits, there is a great probability that it belongs to the same species. 
Unfortunately, however, the hinder part of the cranium of G. leptodus^ is unknown, 
and it might, therefore, be inferred that the present specimen belongs to that species ; 
the rostrum of the latter differs, however, so widely from G. gangeticus that it is 
probable that the hinder part of the cranium would likewise differ more widely from 
that of the latter than the present specimen does : still the specific reference of the 
latter must be regarded as provisional. 
Undetermined mandibular symphysis. — In plate XXXI. fig. 4 there is represented 
from the oral aspect the extremity of the mandibular symphysis of a gharial from 
the Siwaliks of Perim Island which may possibly belong to a small individual of the 
present species. The free extremity is unfortunately imperfect, but the direction of 
the anterior alveolus showed that this contained the first tooth. This being 
determined it is evident that the specimen differs from G, gangeticus by the absence 
of any lateral expansion at the second tooth. Unfortunately neither of the pre- 
ceding specimens show the extremity of the rostrum, but it is not improbable that 
this may have lacked the expansion characteristic of the existing species. That the 
present specimen does not belong to the next species is tolerably evident from the 
absence of a great upward curvature of the extremity which would be necessary to 
make it correspond with the cranial rostrum represented in plate XXXI. fig. 2. 
Specific distinctness and affinity. — Taking the rostrum alone, the marked difference 
in the contour of the facial profile indicates pretty clearly the specific distinctness of 
the form to which it belonged from G. gangeticus : to that form it is proposed to 
apply the name G. hysudricus, as the type specimen was obtained in the neighbour- 
hood of the Satlej valley. If the hinder part of the cranium belong to the same 
species, the distinction from G. gangeticus is more strongly emphasized. If again the 
extremity of the mandibular symphysis from Perim Island be likewise specifically 
identical, the species will differ from the existing gharial by the absence of the 
lateral expansion at the termination of the rostrum. 
Distribution. — The type specimen and the hinder portion of the cranium were 
obtained from the typical Siwalik Hills ; if the extremity of the mandibular 
symphysis belong to the same species its range must be extended to Perim Island. 
No traces of this form have been obtained from the lower Siwaliks of Sind. 
1 The width of the parietal bar between the temporal fossae becomes relatively wider in younger crania, till in a cranium 
of only eight inches in length it is equal to half the interorbital width. 2 Yide infrd. 
