30 

 Synopsis of the Indian species of the subgenus Aristaeus. 



I. Integument pubescent : tbe pleurobranchite in advance of somite 



XIV are distinct filaments ... ... ... ... A. virilis. 



II. Integument glabrous : tbe pleurobrancbire in advance of somite 



XIV are reduced to mere papilla? ... ... ... A. semidentatus. 



11. AristceUS Virilis, Spence Bate. 



Hemipeneus virilis, Spence Bate, Challenger Crustacea Macrura, p. 303, pi. xliv. fig. 4, c? . 

 Hemipeneus tomentosus, Spence Bate, torn, cit., p. 307, pi. xlix. figs. 2, 3, pi. 1. J . 

 Aristseus virilis, Wood-Mason, Ann. Mag. Nat. Hist., Oct. 1891, p. 279. 



Pubescent. Free portion of the rostrum, in the female, three-quarters of 

 the length of the rest of the carapace measured in the mid-dorsal line, upcurved, 

 and reaching far beyond the antennular peduncle and the antennal scale ; in the 

 male only about two-fifths the length of the rest of the carapace, nearly straight, 

 and barely reaching the end of the 2nd point of the antennular peduncle : its 

 carina is lost on the gastric region. The orbital (post-antennular) and post- 

 antennal (branchiostegal) spines are small, especially the former. The cervical 

 groove and the post-orbital crest that runs towards it are indistinct. 



The 6th abdominal somite is more than half as long again as the 5th. 

 Telson much shorter than the endopodite of the caudal swimmeret, armed on 

 either side with 4 spinules. 



Eyes globular, wider than their stalks. The outer flagellum of the anten- 

 nules is from two-thirds (female) to four-fifths (male) the length of the basal 

 joint of the peduncle, the inner flagellum is longer than the whole body : in the 

 male alone there is a curious bend and twist of the base of the inner flagellum. 



The antennal scale is very large, in the male alone its tip is curiously 

 thickened. 



External maxillipeds in the male the same length as, in the female slightly 

 shorter than the first pair of legs : in the male alone the antero-external angle 

 of the propodite is prolonged beyond the articulation of the dactylus, the 

 prolongation being capped with a bunch of hairs. 



The 5th pair of legs, which are the longest, reach about half a dactylus 

 beyond the tip of the antennal scales : the 4th pair are but little shorter. 



The exopodites of the 1st pair of abdominal appendages are a little more 

 than half the entire length of the abdomen (telson excluded). 



The " thelycum," when not concealed beneath a plug of coagulated secre- 

 tion, consists of a nearly vertical triangular or pentagonal plate, lying between 

 the 4th pair of thoracic legs. 



The " andricum" of the 1st pair of abdominal appendages consists of a pair 

 of sub-triangular feebly-interlocking plates, the thickened outer border of which 

 is free and independent in its distal third. 



