87 



The epipodites are small and do not ascend between the gill-plumes. 



The eggs are small and numerous. 



The species of this genus undoubtedly belong to the Xecton. Spence Bate 

 has described 15 species, which, it seems to me, may be reduced to 6 or 7. 



Key to the Indian species of Nematocarcinus. 



I. Rostrum about two-thirds tlie length of the rest of the carapace measured 

 in the middle line, and with its single ventral tooth placed some little 

 way behind the tip : — 



1. Rostrum with about 22 dorsal teeth ... ... ... N. tenuipes. 



2. Rostrum with from 7 to 9 dorsal teeth ... ... ... N. tennirostris. 



II. Rostrum a third or less the length of the rest of the carapace, and with its 



single ventral tooth placed at the tip: — 



1. In the 1st pair of thoracic legs the chela? and not more than a 



third of the carpus lie beyond the antennal scale : — 



i. Rostrum with about 15 small close-set dorsal teeth ... N. cursor. 



ii. Rostrum with about 9 dorsal teeth ... ... N. paucidentatus. 



2. In the 1st pair of legs the chelae and more than two-thirds of the 



carpus lie beyond the antennal scale : rostrum with about 20 



small close-set dorsal teeth ... ... ... N. gracilis. 



46. Nematocarcinus tenuipes, Spence Bate. 



Nematocarcinus tenuipes, Spence Bate, Challenger Crnat. Macrura, p. 812, pi. cxxxii. fig. 6 : Wood-Mason, 

 Ann. Mag. Nat. Hist., Feb. 1891, p. 197. 



? Nematocarcinus productus and intermedins, id. ib., pp. 810, 821, pi. cxxxii. figs. 5, 13. 



It is doubtful whether this species is distinct from N. ensifer S. I. Smith (Bull. Mus. Comp. Zool. X. 1882-83, 

 p. 77, pi. xiii. figs. 1-9 and in Rep. U. S. Fish. Comm. for 1882 (1884), p. 368, pi. vii. fig. 1 and for 1885 (1886), 

 pi. xvii. fig. 2, which occurs on both sides — American and European— of the North Atlantic, in the Mediterranean, 

 and off the Pacific coast of Central America. 



The rostrum is about two-thirds the length of the rest of the carapace 

 measured in the middle line, is continued nearly to the after limit of the gastric 

 region as a faint carina, and is gently ascendant : it is armed dorsally with about 

 22 teeth, most of which are articulated and the posterior 10 or 12 are close-set, 

 and ventrally with a single tooth placed not far from the tip. 



The gastric region is incompletely defined by fine grooves, the branchial 

 regions are defined dorsally by a fine low ridge, and there is a dimple in the 

 hepatic region. The post-antennular and branchiostegal spines are sharp, the 

 former being the larger. 



None of the abdominal terga are distinctly carinated, but the 3rd has its 

 posterior border strongly and subacutely produced in the middle line. The 6th 

 somite is twice as long as the 5th. The telson, including its strong terminal 

 spines, is as long as the exopodite of the caudal fan. 



Eyes reniform, of good size. The antennular peduncle reaches a little more 



