73 



This genus is very little different from Carcinoplaa', Pilumnoplax, Litochira 

 etc. and perhaps ought rather to be regarded as a subgenus of Carcinoplax than as 

 an independent genus. All that separate it from Carcinoplax (e. g. C. hngt- 

 manus) are the perfectly square carapace, the less distinct endostomial ridges, 

 and the spiny merus joints and slender hairless dactyli of the legs. 



Psopheticus Sfridulans, Wood-Mason. 



Psox>liet'Cus stridulans, Wood-Mason, Illustrations of the Zoology of the Inveefcigator, Crnstacea, pi. v. fie- 1 

 fl892) : Alcock, Ann. Mag, Nat. Hist., May 1894, p. 402. 



Carapace three-fourths as long as broad, smooth and polished, crossed trans- 

 versely in its posterior half by a broad groove which is continued obliquely 

 across the pterygostomian regions to the angles of the mouth. 



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 gra- 

 nular 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 stri- 

 'dulans. 



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. 



The chelipeds in the adult male are a little more, in the adult female a little 

 less, than twice the length of the carapace, and are smooth and polished, as also 

 are the legs. The arm has a strong upstanding claw-like tooth near the middle 

 of its upper border, one or two spinUles near the far end of the outer border, 

 and a spinule near the far end of the inner border : the wrist has both the inner 

 and the outer angles spiniform. 



The third pair of legs, which are slightly the longest of the four, are rather 

 more than two-and-a-half times the length of the carapace. In all, the anterior 

 edge of the meropodites is armed with spines and the same edge of the carpo- 

 podites with spinules — these being least numerous and least distinct in the case 

 of the first pair. 



Colours in glycerine : chelipeds and legs rather dusky red ; carapace dusky 

 red behind the transverse groove — which forms a very sharply-defined red band 

 — livid red, or almost violet, in front of it; eyestalks almost purple, eyes 

 purplish-black. Eggs in life magenta. 



The carapace of the largest male is 15 millim. long and 20 millim. broad. 



Only known, so far, from the Andaman Sea : 2 males and a female from 

 173 fms., 2 males and a female (Types of the species and genus) from 188-220 

 fms., 7 females (3 with eggs) from 18-5 fms., a male and 4 females from 370-419 

 fms. 



