252—12 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
value, it may be provisionally referred to that genus with the name of R. grandi- 
scutata. 
The very large size of the type specimen indicates that B. grandisciitata con 
siderably exceeded in its dimensions any of the existing species, and its length may 
be roughly estimated as probably not less than seven feet. 
Group B. ARIINA. 
Characters. — Anterior and posterior nostrils approximated. 
Genus. ARIUS, Cuv. and Val.^ 
Characters. — Head osseous above ; superior cranial bones covered with a granulo- 
radiate sculpture; teeth on the palate fixed; upper jaw longer than the lower. 
The genus is divided into groups from the structure of the teeth. 
Distribution. — The genus is spread over the whole of tlie tropical regions, and 
comprises a very large number of species. From India and the adjacent countries 
twelve species are recorded by Dr. Day.^ 
I. Vomerine teeth are present.^ and form a continuous or slightly interrupted hand, 
more or less confluent with the 'palatine teeth. 
A. Teeth on the palate villiform. 
Arius, sp. a. 
{From the SiwaliJcs). 
History. — The specimen noticed below was obtained from the Siwalik Hills, and 
belongs to the Cautley collection of the British Museum ; it has not been hitherto 
described. 
Cranium. — The specimen represented in plate XXXVI. fig. 2 consists of the 
hinder part of the cranium of a very large siluroid, showing the basicranial axis, 
and a considerable portion of the bones of the upper part of the face. Nearly the 
whole of the supraoccipital {sup.) and a considerable portion of the adjacent lateral 
bones are preserved, as well as the hinder extremities of the frontals {fr.) ; and in order 
to exhibit the form of this part of the cranium when complete the specimen has been 
restored in outline from the corresponding portion of the cranium of the existing 
Arius latiscutatus of West Africa. 
Comparing the fossil with the cranium of the last-mentioned species, the resem- 
blance between the two is so close, that not only may it be said without doubt tliat 
the former belongs to the genus Arius, but that it belongs to the same group as the 
existing species. The cranium of the latter is described as rather broad and 
depressed, and coarsely granulated above ; the supraoccipital process is broader than 
long, subtriangular, with the lateral margins undulated, and with a median longitu- 
dinal ridge ; the fonticulus on the upper side of the head is very narrow, tapering 
behind, and extending to the base of the supraoccipital process. The largest 
skeleton in the British Museum measures fifty-two inches in length, and the fossil 
1 “Hist. Nat. d Poissons,” vol. XV. p. oo (IblO). 
2 “Fishes of India,” pp. 458-463 (1878). 
