Carminhgical Fauna of Indin. 309 



straiglit line with the postei^o- lateral borders. Front square-cut, strai^'lit, 

 promineufc, entire, not well delimited from tlie supra-orbitil angles, a 

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



Uj)per border of orbit very sinuous and with a single faint short 

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

 loosely in the orbital hiatus. The antennules fold transversely. 



Mouth aud external maxillipeds as in Eiicraie. 



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

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

 of the merus. 



In both sexes the abdomen consists of seven separate segments, and 

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

 between the last pair of legs. 



Dutrihiitinn : Andaman iSea. 



Key to the (Indian) species of Psopheticus. 



T. Carapace quite quadrilateral, the fronto-orbital border 

 being equal to the greatest breadth of the carapace : 

 meropodites of legs with numerous spines ... ... P. striiliilcoi.'i. 



II. Carapace subqaadrilateral, the fronto-orbital border 

 being about three-fourths its greatest breadth : 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, Ana. Mag. Nat. Hist, May 1891, 

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



Carapace quite quadrilatei'ul, three-fourths as long as broad, smooth 

 and polished, crossed transversely in its postei-ior half by a broad groove 

 which is continued obliquely across the pterygostomian legions to the 

 angles of the mouth. 



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

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



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

 obliquely-pi'ominent spine at the junction of the antero-lateral aud 

 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 stridnhins. 



The major diameter of the leuiform ej'^e is between a sixth and a 

 seventli the breadth of the carapace; tliough the orbit does not conceal 

 the eye its edges are well and cleanly cut. 



651 



