242—2 INDIAN TERTIARY AND POST-TERTIARY VERTEBRATA. 
evidence of the physical conditions of those regions in the pliocene epoch. 
Infra-Siwalik fishes. — The fishes of the infra-Siwalik marine rocks of the Punjab 
and Kach are known merely by two specimens described in the sequel ; while a 
glimpse of the fish-life of the tertiaries of the more southern regions is afforded by a 
third specimen. The brief literature referring to these specimens is quoted in the 
sequel. 
Subclass I. PAL.dEICHTHYES. 
Okder. CHONDROPTERYGII. Suborder. PLAOIOSTOMATA. 
Section I. SELACHOIDEI. 
Family I. GABCHABIIBuE. 
Genus. CARCHARIAS, Linn.^ 
Characters. — Teeth flat and triangular, with either smooth or serrated edges. 
Distribution. — The genus is represented by between thirty and forty existing 
species,^ which are inhabitants of tlie tropical and (more rarely) temperate seas ; and 
it is probable that some of the fossil forms described under the names of Corax and 
Hemipristis are not generically separable. Carcharias gangeticus, which is found from 
India to Japan, ascends tidal rivers to distances considerably above the influence of 
the tides,® and is also found in inland lakes in the Fiji Islands'* — the latter habitat 
being of especial interest in relation to the specimens from the Siwaliks. 
Carcharias, sp. 
(From the Siwaliks.J 
History. — The specimens noticed below are described for the first time. 
Teeth. — The four teeth represented in plate XXXV. figs. 12-15 are selected from 
numerous specimens collected by Mr. Theobald in the Siwaliks of the Punjab; 
figs. 12, 13 being from the upper, and 14, 15 from the lower jaw. The upper teeth 
show strongly-marked serrations, and agree very closely with those of Carcharias 
glaucus^ and C. gangeticus ; the notch on the anterior border being very slight, as in 
the latter species. The lower teeth exhibit much less clearly-marked serrations, but 
the presence of such serrations indicates that they belong to the same group as that 
containing the two above-mentioned species. In their narrower bases both the lower 
teeth differ from those of C. glaucus and C. gangeticus : the specimen represented in 
fig. 15 is probably one of those situated close to the mandibular symphysis. 
Affinities. — It is probable that the specimens are insufficient for specific deter- 
mination ; and all that can be safely said of them is that they indicate a form allied to 
the two species mentioned above. The occurrence of this form in the Siwaliks of the 
1 “ Syst. Nat.” ed. 12. vol. I. p. 400 (1766). 
2 Thirty-five species are enumerated in Gunther’s “ Catalogue of Fishes,” vol. VIII. pp. 358-375 (1870). 
- 3 Day “ Fishes of India,” p. 715 (1878). 4 Gunther ” Study of Fishes,” p. 205 (1880). 
5 Compare the figure in Gunther’s “ Study of Fishes,” p. 317. fig. 112 (1880). 
6 Gunther ” Catalogue of Fishes,” vol VIII. pp. 363-364 (1870). 
