1900,] A. Alcock — Carcinological Fauna of India. 403 



ii. Inner angle of the wrist produced to form a 

 long spine : a patch of hair on the outer 

 surface of the hand of the male, near the 



finger cleft P. onyx. 



2. Teeth of the antero-lateral border not salient, in- 

 conspicuous : regions of the carapace not, or hardly, 

 indicated : — 



i; A subterminal patch of bristles on the outer 



surface of the fixed finger of the female P. andamanica. 



ii. Fingers of female nude P. pusilla. 



II. Carapace decidedly broader than long : front little pro- 

 minent and decidedly sinuous : the antennules fold nearly 

 transversely P. barbata. 



90. Ptychognathus dentata, de Man. 



Ptychognathus dentatus, de Man, in Weber's Zool. Ergebn. Niederl. Ost-Ind. II. 

 1892, p. 318, pi. xviii. fig. 9. 



Carapace inappreciably broader than long, flat but not particularly 

 depressed, its regions quite distinct, as also are the cervical and bran- 

 chial groves and a pair of post-frontal tubercles : on the posterior part 

 of each epibranchial region, obliquely parallel with the postero-lateral 

 borders, is a fine ridge. 



Front prominent, laminar, nearly straight, its extent is two-fifths 

 the greatest breadth of the carapace. 



Antero-lateral borders of the carapace cut into three sharp salient 

 teeth, of which the first is much the largest, and the third much the 

 smallest. 



Upper border of the orbit very sinuous. The antennules fold very 

 obliquely. Anterior border of the buccal cavern not granular, but 

 having a median horizontal tooth. 



Exognath oval, with a smooth and strongly convex surface : its 

 greatest breadth in the male is more than twice that of the ischiognath, 

 but in the female is only a little more than that of the ischiognath. 



Chelipeds of the male more than L§ times the length of the cara- 

 pace, smooth : inner angle of the wrist acute, but not spiniform : palm 

 higher than long, inflated at the postero-inferior angle, and having a 

 tussock of hairs in the middle of its inner surface: dactylus more than 

 twice the length of the upper border of the palm, longer slenderer and 

 less strongly toothed than the fixed finger : both fingers though hollowed 

 at the tip are sharp-pointed. In the female the chelipeds are about as 

 long as the carapace ; the inner angle of the wrist is spiniform ; the 

 palm is not swollen and is nude, and its outer surface is traversed, near 

 the lower border, by a fine raised line which extends nearly to the tip 

 of the. fixed finger. -._.,_-_... 



