3o6 Memoirs of the Indian Museum. [Vol. V, 



Alpheus paludicola is allied to A. euphrosyne', de Man, and A. microrhynchus, 

 de Man, and would find a place alongside these forms in the key which is supplied 

 in the Report on the ' Siboga ' Alpheidae. It agrees with these species and differs 

 from A. edwardsi, Aud., A. crassimanus, Heller, and other closely related forms in 

 the absence of a spine at the distal end of the infero-internal margin of the merus of 

 the first peraeopods. It resembles A. euphrosvne in having both margins of the palm 

 of the small chelipede of the male notched and A . microrhynchus in the diminutive 

 size of the rostrum and large size of the eggs. 



From A. euphrosyne the Chilka species may be distinguished by the much smaller 

 rostrum, the narrower antennal scale, the more slender form of the small chela of the 

 male (in A. euphrosyne it is only four times as long as broad), the different proportions 

 of the segments in the carpus of the second peraeopods and the larger eggs. The large 

 chela of A. euphrosyne has not been figured, but is apparently somewhat similar to 

 that of A. paludicola. De Man describes granulations at the base of the fixed finger 

 similar to those found in the Chilka species ; but he also notes the existence of granu- 

 lations on certain parts of the outer surface, and of these in A . paludicola there is no 

 trace. In A. euphrosyne, moreover, the large chela is more slender, about three 

 times as long as broad. 



In A. microrhynchus the rostrum, though small, is decidedly larger than in the 

 species from the Chilka Lake, there are no granulations on the large chela, the upper 

 and lower margins of the small chela of the male are not notched behind the fingers 

 and the proportional lengths of the carpal segments in the second legs are different. 



Specimens were semitransparent in life, the black gastric mass and the intestinal 

 canal being clearly visible through the carapace. The rostrum was brownish-red and 

 the antennular peduncles and outer margins of the antennal scales were tinged with 

 the same colour. At the hinder end of the carapace and of each of the abdominal 

 somites was a transverse band of brown pigment, sometimes tending to a bluish-green 

 shade laterally. The telson and uropods were as a rule dusky, often with a faint 

 speckling of red and not infrequently suffused with light blue. The inner surface of 

 the larger chela was reticulated proximally with dull brown. The base of the fingers 

 and the ridges on the palm were greenish or greenish-blue, the tips of the fingers 

 pink. The outer surface was pale. The small claw was feebly pigmented and the 

 other legs entirely transparent. 



Two individuals lived for about three months in a shallow dish, fresh water 

 being added occasionally to compensate for evaporation. They constructed only the 

 most rudimentary burrows, using the last three pairs of legs in excavation and their 

 pleopods in wafting away the mud. Whenever possible the burrows were dug under- 

 neath shells or pieces of weed ; they were entirely horizontal and never much longer 

 than the animal. The large chela was used as a lever in removing obstructions. 



Alpheus paludicola is common in the Chilka Lake; specimens were found at no 

 less than twenty-one different stations. It was found over an area extending from 



For references to these species see de Man, Decap. ' Sihoga' Exped., II, Alpheidae. p. 413. 



