41 



carapace and are hardly stouter than the legs. Except in respect of the fingers 

 they have much the same form as, though slenderer proportions than, those of 

 Stenorhynchus, but the arm is much more strongly and elegantly curved : the arm 

 and wrist are moderately inflated, the former joint, like the ischium, having its 

 lower edge more or less granulate : the palm is compressed, with the edges den- 

 ticulate : the fingers are strongly compressed, and have the cutting edges accu- 

 rately and completely apposable throughout, being almost imperceptibly denti- 

 culate near the tips only. 



In the female the chelipeds have the same general form as in the male, but 

 differ in being much slenderer and in having the lower edge of the ischium and 

 merus strongly spinate. 



The legs are slender and filiform, about one-fourth of their length being 

 contributed by the filamentous dactylus : those of the second pair are the longest, 

 being about four times the length of the carapace, rostrum included, and more 

 than two-and-a-half times the length of the chelipeds. 



In both sexes the first segment of the sternum is modified to assist in repro- 

 duction, being sharply compressed and produced in a vertical direction down- 

 wards : in the male, the carina so formed is notched in the middle line so as to 

 form, with the tip of the abdomen, a sort of tunnel for the enormously deve- 

 loped first pair of abdominal legs : in the female it is either notched or entire 

 and forms a high front wall to the brood-pouch, and the openings of the oviducts 

 are pushed forwards so as to lie immediately behind it. 



The length of the average adult female carapace is 8'5 millim., the breadth 

 7 millim. The adult male is a little smaller and has the anterior pair of abdo- 

 minal legs enormously developed. 



Numerous males and egg-laden females have been taken, in the Andaman 

 Sea 185 to 375 fms., and off the Malabar coast, 360 and 406 fms. 



The eggs are few in number and are singularly large, being over a milli- 

 metre in diameter. 



Physachceus tonsor, Alcock. 



Physachxus tonsor, Alcock, J. A. S. B., Vol. LXIV. pt. 2, 1895, p. 176, pi. iii. fig. 3: 111. Zool. R. I. M. S. 

 Investigator, Crust, pi. xviii. figs 2, 2a. 



The female, which is the only sex represented in the collection, differs from 

 the female of Physachseus ctenurus in the following particulars : — 



(1) the gastric region of the carapace, instead of a single large spine, has 

 several smooth tubercles ; and the large spine behind the cardiac region is 

 coarser, and is recurved instead of procurved : the post-ocular constriction is 

 less marked : 



