250 TRIONYCHID ®. 
Trionyx gangeticus, part., Gray, Cat. Sh. Rept. i. p. 66 (1855), and 
Suppl. p. 97 (1870); Theob. Proc. As. Soc. Beng. 1875, p. 171, and 
Cat. Rept. Brit. Ind. p. 28 (1876). 
sewaare, Gray, Ann. § Mag. N. H. (4) x. p. 836 (1872), and 
Proc, Zool. Soc. 1873, p. 50, figs.; Theob. Proc. As. Soc. Beng. 
1875, p. 172, and Cat. Rept. Brit. Ind. p. 29. 
bellii, Gray, Ul, cc. pp. 887 & 51. 
Nilssonia formosa, part., Gray, Proc. Zool. Soc. 1873, pp. 45 & 46, 
figs. 
Trionyx buchanani, Theob. Proc. As. Soc. Beng. 1874, p. 78. 
? Trionyx nigricans, Anders. Ann. § Mag. N. H. (4) xvi. p. 284 
(1875). 
Costal plates eight pairs, the last well developed and in contact 
throughout on the median line; two neurals between the first pair 
of costals; plates coarsely pitted and vermiculate. Epiplastra nar- 
rowly separated from each other in front of the entoplastron, which 
forms an obtuse or a straight angle; plastral callosities very large, 
hyo-hypoplastral, xiphiplastral, and in old specimens entroplastral. 
Dorsal skin of young with longitudinal ridges of small tubercles. 
Head moderate ; snout (on the skull) a little longer than the dia- 
meter of the orbit ; interorbital region, in the adult, as broad as 
the nasal fossa ; postorbital arch somewhat more than half the dia- 
meter of the orbit in the adult ; mandible without strongly raised 
inner edge or longitudinal symphysial ridge ; the diameter of the 
mandible at the symphysis exceeds the diameter of the orbit. Olive- 
brown above and beneath; head, neck, limbs, and border of shell 
light-dotted ; head with large yellow spots, viz. across the snout, 
behind the orbit, at the angle of the mouth, on the tympanic region 
and on the chin; these spots become indistinct in the adult, the 
head of which is more or less closely spotted or vermiculated with 
black; dorsal disk in the young with dark marblings and four or 
six very large ocelli. 
Length of dorsal disk 40 centim. 
Ganges. 
a, Ad., skel. Calcutta. 
b-c, df, Yg., spir. Ganges. 
g. Yg., skull. Ganges. W. Theobald, Esq. [ P.]. 
h. Her., skull & shell. Bengal. W. Theobald, Esq. pf 
7. Yo., skull & carapace. India. Dr. Falconer [P.]. 
k. Yg., spir. P 
i. Ad., skull. —? 
5. Trionyx formosus. 
Trionyx formosus, Gray, Proc. Zool. Soc. 1869, p. 217, pl. xv. fig. 1, 
and Suppl. Cat. Sh. Rept. i. p. 99 (1870) ; Theob. Cat. Rept. Brit. 
Ind. p. 31 (1876). 
jeudi, part., Gray, Suppl. p. 98. 
—— peguensis, Gray, Suppl. p. 99; Theob. Proc, As. Soc, Beng. 1875, 
p. 176, and Cat. Rept. Brit. Ind. p. 31; Anders. Zool. Res. 
Yunnan, p. 786, pls. Ixx.—Ixxiii. (1879). 
Nilssonia formosa, Gray, Ann. § Mag. N. H. (4) x. p. 333 (1872). 
