Mediterranean also in water of 20 — 30 and off" the west coast of the Indian peninsula in 

 water of 28 fathoms. 



Key to the known species of the genus Acgcon (Risso) Guér.-Ménev. '). 



a x Second lateral carina of the carapace interrupted anteriorly by 



a well-defined hepatic groove; lateral parts of i st and 2 nd 



abdominal somites irregularly lobed, without sharp longitu- 



dinal kcels continuous with those 011 the carapace. 



b x Two or three tubercles, forming an oblique transverse row, 



between the median and first lateral carinae. 



Supra-marginal carina of carapace serrate, abdominal pleura 



subacute , cataphracta (Olivi) 



(G. Olivi, Zoologia adriatica, 1792, p. 50, pi. 3, fig. 1. — Th. R. R. Steb- 

 BING, South African Crustacea, Cape Town, 1900, p. 50 (ubi synon.) 



ó 2 Surface between the carinae of the carapace smooth, without 



tubercles. 



c x Supra-marginal carina of the carapace smooth. 



rf x Antepenultimate thoracic sternum in the adult male and 



in the adult female smooth, in the male the two postenor 



thoracic sterna sharply carinated, in the female also 



smooth. 



Second peraeopods not different in the two sexes, reaching 



in both but a little beyond the carpal articulation of the 



hand of the anterior pair pennata (Bate) 



d t The three last thoracic sterna in the male sharply carinated, 



in the female the carination of the antepenultimate 



sternum is distinct, but that of the last two is obsolescent. 



Second peraeopods in the adult male and in the young as 



long as in the typical A. pennata (Bate), in the adult 



female almost as long as the anterior pair . . . pennata (Bate), var. affinis Alcock 



(A. ALCOCK, A descript. Catal. Indian Deep-Sea Crust, Calcutta 1901, p. 1 1 8.) 



c„ Supra-marginal carina of the carapace serrate. 



d x Median carina of the carapace with S — 10 teeth or serrations. 



e x Abdominal pleura with truncated tips. 



f x On either side of the middle line of the 2 nJ abdominal 



somite there is a broad sinuous ridge, that extends 



obliquely throughout the length of the somite. 



Rostrum not cleft at tip propcnsalata (Bate) 



(C. Spence Bate, Report Challenger Macrura, 1888, p. 496, PI. XC, 

 figs. 2, 3; PI. LXXXVI, fig. 5.) 



1) Kor drawing up this key use has chiefly been made of the Synopsis of the Indian species in Mr. Stanley KEMP's paper, in: 

 Records Indian Museum, Vol. XII, Part VIII, Calcutta 1916, p. 375. 



