1914-] S. Kemp : Notes on Crustacea Decapoda. 



99 



Third maxillipede with exopod. No arthrobranchs at base of 

 peraeopods ; epipods present on at least first three pairs. Carpus 

 of second peraeopods composed of three segments. 



Nearly all the species of this genus stand in need of re-defini- 

 tion. They are for the most part based on the character of the 

 rostrum which, in this genus, is subject to even greater variation 

 than in Spirontocaris or Hippolvte. 



The three species known from the Indian coasts may be 

 separated thus : — 



I. Dactyli of last three pairs of peraeopods with con- 

 spicuous spines on margin. 



A. Form very slender, basal segment of antennular 



peduncle three times as long as wide, antennal scale 

 more than six times as long as wide; legs short, 

 second pair not reaching to end of eyes ... ... L. pygnineus. 



B. Form stouter, basal segment of antennular peduncle 



twice as long as wide, antennal scale not more than 

 four and a half times as long as wide (less in 

 adults) ; legs longer, second pair reaching beyond 

 end of antennular peduncle ... L. mucronatus. 



II. Dactyli of last three pairs of peraeopods simple 



claws, without spines on margin ... ... L. nnoplonyx. 



I have seen no specimens of the very curious Laireutes ceylon- 

 ensis described by Pearson from the Ceylon pearl banks.* The 

 species differs from all other members of the genus with which 

 I am acquainted in the peculiar spinulation of the carapace and 

 antennal scale and in the armature of the dactyli of the last three 

 peraeopods. In many respects it appears to be allied to Nobili's 

 Laireutes paronae which is here regarded as the type of a new 

 genus^ Gelastocaris. 



Latrcutes pygmaeus, Nobili. 

 Plate II, figs. 7, S ; Plate III, figs. 1-7. 



1904. Latreutes pygmaeus, Nobili, Bull. Mus. d'hist. Nat., Paris, p. 230. 

 iQoO. Latreutes pygmaeus, Nobili, Bull. sci. France Belg., XL, p! ^^-j . 



pi. iii, figs, 4, a-h. 

 iQof). JMti'futes pygmaeus, Nobili, Ann. Sci. nat. Zool. (9), IV, p. 41. 



lyarge series of specimens obtained at Kilakarai and Pambaii 

 in S. India may undoubtedly be referred to[ithis species, which 

 is a very close ally of the Atlantic L. ensifer. 



Nobili's account may be supplemented as follows : — 



The small dorsal spine on the carapace behind the orbit 

 is movable, as in L. ensifer, and not fixed as in certain other 

 species of the genus. The rostrum is sometimes wholly unarmed, 

 but more usually bears from i to 3 dorsal teeth and i to 3 

 ventral teeth, all situated in the distal third. The apex ma}- be 

 acute or bluntly rounded (pi. II, figs. 7, 8 ; pi. Ill, figs. 1-3). 



Close to the cornea on the inner and superior aspect of the 

 stalk the eye bears a small conical process similar to that described 

 by Nobili in allied species. 



' Ceylon Pearl Oyster Rep., IV, p. 81, pi. ii, figs. 7, 7 a — e. 



