30 



Synopsi* of tlir fudian species of the mbgewiu Aristaws. 



I. Integamont pubescent: the pleurobrauchiro in advance of somite 



XIV are distinct filaments ... ... ... ... A. tirilii. 



II. Integument glabrous : the pleurobranchia: in advance of somite 



XIV are reduced to mero papilhe ... ... ... .1. nemidantahu. 



11. AristteUS Virills, Spence Bate. 



Hemipeneus virilis, Spenco Bate, Challenger Crustacea Mncrurn, p. 303, pi. xliv. fig. 4, <f . 

 Hemipeneus tomentoeux, Spence Hate, torn, cit., p. 307, pi. xlix. figs. 2, 3, pi. I. ? . 

 Arista-it* tirilix, Wood-Mnson, Ann. Mug. Nnt. Hint., 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 ba- a I 

 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 maxillipcds 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 flu- dactylus, the 

 prolongation being capped with a bunch of hairs. 



The 5th pair of legs, which are the longest, roach 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 pent atonal plate, lying bet ween 

 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 bonier of \vhich 

 is free and independent in its distal third. 



