402 Memoirs of the Indian Museum. [Voi,. V, 1916.] 



vided with four corneal lenses, one on each side and a pair, partially fused in the 

 middle. The third and fourth leg-bearing somites are quite distinct and there may 

 be a pair of spines on the last abdominal somite on either side of the telson. 



The telson (text-fig. 5 A) is longer than in the female and is totally different in 

 form. The upper surface is flattened and U-shaped in outline and posteriorly slopes 

 sharply downwards to a long drawn-out apex resembling a large spine. There are 

 two setae on either side at the base of this spine, but there is no trace of the pair of 

 terminal spinules found in the female. 



The ultimate peduncular segment of the antennule is enlarged and bears sensory 

 setae. As in P. longipes both inner and outer flagella are composed of four segments. 

 The terminal segment of the antennal peduncle is provided with eleven transverse 

 rows of setae. 



The third maxillipedes (text-fig. 5 b) have a well-formed exopod and the basal 

 segments of the first four legs are greatly expanded and their exopods very strongly 

 developed. 



The pleopods on the first and second abdominal segments are illustrated in text- 

 fig s - 5 e , /• O n the third and fourth segments (text-fig. 5^) they are replaced by 

 two pairs of long setae, on the fifth by a pair of backwardly directed teeth, each 

 bearing a small setae behind the apex. On the sixth there is a single pair of setae. 



The uropods (text-fig. 5 g) are more slender than those of the female, but do not 

 differ markedly in structure. 



I,arge females of P.culicoides reach a total length of about 4 mm.; males are a 

 trifle smaller, rarely exceeding 3 J mm. 



The species differs conspicuously from all others of the" same genus in the pre- 

 sence of only a single oblique ridge on the carapace. 



Living females in their form and movements bore a curious resemblance to pu- 

 pae of mosquitoes. Both sexes were of a pale brown colour. 



We obtained females in abundance in all parts of the main area of the lake in 

 nets drawn over the surface of the mud at depths of from 6 to 12 ft. Males were 

 found in company with the females, but were much scarcer. A few females were 

 found at the inner end of the outer channel in September in water that was almost 

 or quite fresh. Earlier in the year, when the water in this locality was as salt as 

 that of the sea in the vicinity of the lake, we failed to find any specimens. The 

 species is evidently a permanent inhabitant of the main area of the lake, living in 

 water that varies in specific gravity from 1/000 to i'OT.5. 



The three species of the genus hitherto known are recorded from Japan, the Gulf 

 of Manaar, the Sulu Archipelago and the Gulf of Siam. 



