152 Memoirs of the Indian Museum. [Voi,. V, 



corner of the basal joint more produced. The distal part of the outer margin of the 

 basal joint is armed with numerous long plumose setae in the position indicated by 

 the notches in Hansen's figure and as depicted by Nakazawa. 



The antennal scale, which reaches to the distal end of the antennular peduncle, 

 is as figured by Hansen, but the basal joint from which both the scale and antennal 

 peduncle spring, is armed with three strong spines at the inner corner, at the base 

 of the peduncle. These spines are not indicated by either Hansen or Nakazawa. 

 The antennal peduncle is very short, not as long as the basal joint of the antennular 

 peduncle. The Indian examples reach a length of 12 mm. 



The natural colouration of this species is described as follows : — Transparent, 

 with a large lateral patch of very pale mauve on each abdominal segment. Brood- 

 pouch tinged with yellow. Two blood-red spots on the telson, one at the base 

 and one near the apex. Eyes pale glaucous green. 



Rhopalophthalmus egregius occurs abundantly all over the Chilka Lake, especially 

 on a muddy bottom and among the weed Halophila ovata. It has, however, also been 

 taken on clean sandy ground. Although taken at Barkuda Id. within a few yards of 

 the shore, it was usually captured out in the lake in water from 4 to 12 ft. deep. It 

 was never observed close in to the rocks or in very shallow water, and in this respect 

 its habits differ markedly from those of Macropsis orientalis and Potamomysis 

 assimilis. Apparently it lives mainly at some distance below the surface, perhaps 

 only a few inches above the bottom. The species is gregarious. 



Sub-family GASTROSACCINAE , Norman. 



Genus GASTROSACCUS, Norman. 



Gastrosaccus muticus, sp. nov. 



Locality. — Outer parts of Chilka Lake, Orissa, E. coast of India. 



Description. — Very closely allied to Gastrosaccus spinifer, Goes. 



Dorsal posterior median emarginate border of the carapace with a fringe of from 

 six to nine slender filaments. 



Fifth segment of the pleon without a dorsal spine-like projection. 



Antennules with three or four short strong spines on the outer edge of the second 

 joint; a single similar spine on the outer edge of the third joint about one-quarter 

 of the length of the joint from the distal end. 



Antennal scale reaching to the distal end of the second joint of the antennular 

 peduncle and slightly shorter than its own peduncle ; slightly less than four times as 

 long as broad, outer margin terminating in a strong spine beyond which the apex of 

 the scale is not produced. 



Telson less than three times as long as broad at its base, with about fourteen 

 spines on its outer margin , only the terminal spines conspicuously larger than any 

 of the remainder and equal in length to one-eighth of the length of the telson ; telson 

 cleft for one-sixth of its length. 



Inner uropods equal in length to the telson plus its terminal spines, with four 



