16. G@EOEMYDA.—CHAIBASSIA, 139 
3. Geoemyda depressa. 
Geoemyda depressa, Anders. Ann. § Mag. N. H. (4) xvi. p. 284 
(1875), and Zool. Res. Yunnan, p. 721, pls. lv., lvi., & Ixxv. B. 
figs. 1-5 (1879). 
arakana, Theob. Cat. Rept. Brit. Ind. p. vii (1876). 
Shell much depressed, the depression increasing from before back- 
wards, the shell being somewhat expanded across the inguinal 
region ; only the posterior border serrated; second vertebral about 
as long as broad, narrower than the costals; nuchal longer than 
broad. Plastral shields as in G. spinosa and G. grandis. Carapace 
light brown ; plastron and lower surface of marginals yellow, the 
plastral shields with a few broad black rays ; the interval between 
the axillary and inguinal notches black. Head leaden, neck pale 
yellowish brown; limbs of the latter colour, with the large scales 
dark, almost black. 
Length of carapace 24 centim. 
Aracan. 
a. 9, shell. Aracan. W. Theobald, Esq. [E.]. 
b. 2, shell. Aracan. R. Lydekker, Esq. [E. }. 
The following genus requires further investigation :— 
CHAIBASSIA. 
Chaibassia, Theobald, Cat. Rept. Brit. Ind. p. 6 (1876); Anders. 
Zool, Res. Yunnan, pp. 718, 720 (1879). 
Characters of Geoemyda, but the hypoplastron is usually attached 
to the carapace by ligament *, and a bony temporal arch is present. 
Feet not webbed. (Anderson.) 
North-eastern India. 
1. Chaibassia tricarinata. 
Geoemyda tricarinata, Blyth, Journ. As. Soc. Beng. xxiv. p. 714 (1856); 
Jerdon, Proc. As. Soc, Beng. 1870, p. 69; Gray, Suppl. Cat. Sh. 
Rept. i. p. 26 (1870). 
Chaibassia tricarinata, part., Theod. 1. ¢. 
tricarinata, Anders. l. c. p. 718. 
Carapace elongately oval, relatively highly arched, with three flat 
and obtuse ridges. A rather elongate nuchal shield. Plastron 
notched posteriorly. Hind foot rather club-shaped; claws large, 
hooked, and sharp; the two outer fore-claws small. Carapace dark 
reddish brown, the three ridges yellow; plastron pale yellow. 
Length of carapace 14 centim. 
Chaibassa, Bengal. 
* This character has been pointed out by Anderson, whose definition of the 
genus is, however, not very clear, especially owing to some lapsus in his de- 
scription of the disposition of the “ hyposternal process ” abutting ‘‘ against the 
first costal and third marginal.” But as far as I can gather we have here a 
structure similar to that of the fossil Ptychogaster, one of the differences between 
the two genera being that the hypoplastra are more narrowed in the latter, and 
movable upon a transverse hinge. 
