16. GEOESIYDA. CHA.IBASSIA. 139 



3. Geoemyda depressa. 



Geoemyda depressa, Anders. Ann. ^- Mar/. N. 11. (4) xvi. p. 284 

 (1875), and Zool. licfi. Yunnan, p. 721, pis. Iv., hi., A: Ixxv. ii. 

 tigs. 1-5 (1879). 



arakana, Theoh. Cat. Rcpt. Brit. Ind. p. vii (187G). 



Shell mucli depressed, the depression increasing from before back- 

 wards, the bliell being somewhat expanded across the inguinal 

 region ; onlj- the posterior border serrated; second vertebral al)Out 

 as long as broad, narrower than the costals ; nuchal longer than 

 broad. Plastral shields as in G. sjihiosa and G, grandis. Carai)aco 

 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. $ , shell. Aracan. W. Theobald, Esq. [E.]. 



b. 5, shell. Aracan. R. Lydekker, Esq. [E.]. 



The following genus requires further investigation : — 



CHAIBASSIA. 



Chaibassia, Theobald, Cat. liept. Brit. Ind. p. 6 (187G) ; Anders. 

 Zool. lies. 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. 

 Peet not webbed. {Anderson.) 



North-eastern India. 



1. Chaibassia tricarinata. 



Geoemyda tricarinata,5(;/;;/<,t7bM?-«. As. Soc. Beng. xxiv. p. 714(18oG); 



Jerdon, Proc. As. Soc. Beng. 1870, p. 69 ; Gray, Suppl. Cat. 8h. 



Bept. i. p. 26 (1870). 

 Chaibassia tricarinata, part., Theoh. I. c. 

 tricarinata, Anders. I. 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 11 centim. 



Chaibassa, Bengal. 



* This character has beeu 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 " hyposterual 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 Pff/chogaster, one of the differences between 

 the two genera being that the hypopkstra are more narrowed in the latter, and 

 moyable upon a transverse hinge. 



