302 A. Alcock — Qarcinological Fauna of India. [No. 3, 



the carapace is very much broader, and its antero-lateral borders are 

 much more arched, the frouto-orbital border being relatively much 

 less extensive ; (2) the supra-orbital angles are almost merged in the 

 front, and the median notch of the front is almost obsolete ; and (3) 

 the orbital hiatus is not stopped up by any process of the basal 

 antenna- joint. 



Carapace deepish, subquadri lateral, usually much broader than 

 long, smooth and with little or no distinction of regions, convex fore 

 and aft, very slightly so from side to side. 



The extent of the fronto-orbital border is much less than two- 

 thirds the greatest breadth of the carapace, and the antero-lateral 

 borders, which are toothed, are well arched. Front square-cut nnd 

 straight, faintly notched or longitudinally grooved in the middle line, 

 not very distinctly demarcated from the supra-orbital angles, from a 

 third to a fourth, or less, the width of the carapace. 



The upper border of the orbit is sinuous and may, or may not, 

 be marked 'by a single faint suture line. The basal antenna joint is 

 short and the antennal flagellum stands loosely in the open orbital 

 hiatus. The antennules fold transversely. 



Buccal cavern, palate, and external maxillipeds as in Eucrate. 



Chelipeds subequal, much more massive and sometimes, in the 

 adult, much longer than the legs. 



Legs slender, unarmed ; in the last pair the propodite and dactylus 

 are compressed and decidedly broadened for swimming. 



In both sexes all seven abdominal segments are distinct, and in the 

 male the third segment covers the whole width of the sternum between 

 the bases of the last pair of legs. 



Distribution: Indo-Pacific (Indian, Japanese, Californian). 



I exclude from the genus Carcinojplax those species, e.g., setosa and 

 integra, which have the edge of the front turned down and arched : 

 these it seems to me are better associated with Litochira. 



Key to the Indian species of the genus Carcinoplax. 



I. The long diameter of the orbit is nearly three-fourths 

 the width of the inter-orbital space : a spine or tooth at 

 the outer angle of the wrist. Chelipeds in the adult 



male very much longer than the legs C. longimanus. 



II. The long diameter of the orbit is about half the width 

 of the inter-orbital space : no spine or tooth at the 

 outer angle of the wrist. Chelipeds rather shorter than 

 the legs ... .,. , ,, C. longipes. 



