1900.] A. Alcock — Carcinological Fauna of India. 309 



straight line with the postero-lateral borders. Front square-cut, straight, 

 prominent, entire, not well delimited from the supra-orbital angles, a 

 third the breadth of the carapace, or a little less. 



Upper border of orbit very sinuous and with a single faint short 

 suture line. The antennal flagellum, which is of good length, stands 

 loosely in the orbital hiatus. The anteimules fold transversely. 



Mouth and external maxillipeds as in Encraie. 



Chelipeds much stouter than the legs. The legs end in a slender 

 styliform dnctylus, and have one or many spines on the anterior bolder 

 of the merus. 



Tn both sexes the abdomen consists of seven separate segments, find 

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

 between the last pair of legs. 



Distribution : Andaman Sea. 



Key to the (Indian) species of Psopheticus. 



I. Carapace quite quadrilateral, the fronto-orbital border 

 being equal to the greatest breadth of the carapace : 

 meropodites of legs with nnmerous spines ... ... P. stridulans. 



II. Carapace subquadrilateral, the fronto-orbital border 

 being about three-fourths its greatest breadtli : mero- 

 podites of legs with a single spine ... .,. ... P. insignis. 



11. Psopheticus stridulans, Wood-Mason. 



Psopheticus stridulans, Wood-Mason, Illustrations of the Zoology of the Investi- 

 gator, Crustacea, pi. v, fig. 1. (1892) : Alcock, Ann. Mag. Nat. Hist., May 1894, 

 p. 402 ; and Investigator Deep-Sea Brachyura, p. 73. 



Carapace quite quadrilateral, three-fourths as long as broad, smooth 

 and polished, crossed transversely in its posterior half by a broad groove 

 which is continued obliquely across the pterygostomian regions to the 

 angles of the mouth. 



Owing to the large size of the eye and orbit, the extent of the fronto- 

 orbital border is equal to the greatest breadth of the carapace. 



A thin sharp prominent tooth at the outer orbital angle, and an 

 obliquely-prominent spine at the junction of the antero-lateral and 

 postero-lateral borders. 



The subocular and subhepatic regions are inflated, and together 

 form a granular eminence against which a strong spine on the upper 

 border of the arm can be brought to play, producing a sound. Hence 

 the names Psopheticus and stridulans. 



The major diameter of the reniform eye is between a sixth and a 

 seventh the breadth of the carapace; though the orbit does not conceal 

 the eye its edges are well and cleanly cut. 



