154 Memoirs of the Indian Museum. [Voi<. V, 



(3) The fewer spines on the inner margin of the inner uropods, four as against 

 nine to eleven in G. spinifer L . 



(4) In having four spines on the outer edge of the second joint of the antennular 

 peduncle instead of three as in G. spinifer. 



(5) In its smaller size, 7 mm., as against 20 mm. 



(6) In the vastly different form of the exopod of the third pleopods of the male. 

 The third pleopod of the male of G. spinifer has never been figured, but I find by 

 examination of British specimens that it agrees closely with the same appendage in 

 G. sanctus as figured by Sars (1877). 



In the possession of a fringe of slender filaments on the central posterior dorsal 

 margin of the carapace, G. muticus is at once distinguished from all other described 

 species of the genus except G. spinifer and the following new form. 



In life the species is described as being not very translucent, with a large brown 

 spot at the base of the lower antenna and another, posterior to the first, near the 

 hinder end of the carapace. Each of these dark spots was connected with a pale yel- 

 lowish one situated above it. There were two small black spots on each side of the 

 brood-pouch, consisting of single dendritic chromatophores. On the posterior margin 

 of each of the abdominal segments there was a brown dendritic chromatophore on 

 either side, connected with its fellow on the opposite side by a yellow line. The last 

 abdominal segment bore a brown transverse bar at its posterior extremity. The 

 telson was tipped with mingled brown and yellow. The tip of the antennal scale was 

 brown. The eggs were quite colourless. 



G. muticus occurs mainly in the outer channel of the Chilka Lake, but was also 

 taken near Nalbano in the main area. It was invariably found either on a sandy bottom 

 or on one in which the mud was mixed with a considerable amount of sand. Although 

 considerable numbers of specimens were sometimes taken in a single haul of the 

 Q-net, the species is perhaps less markedly gregarious than the others found in the 

 lake. 



The type specimens are preserved in the Indian Museum and are numbered 

 8664/10 in the Museum register. 



Since this paper went to press, I have received specimens of this species from 

 Madras, where they were collected by Dr. Annandale in the Ennur backwater, in 

 water of specific gravity varying from i - ooo to 1*0045 (corrected). The species was 

 apparently quite abundant in this locality. 



Since this paper left my hands, I have received further material of this species 

 from the Chilka Lake, and its examination necessitates the following additional notes. 

 The material altogether comprised 24 males and 46 females. A point of perhaps 

 minor importance is that the number of spines on the outer margin of the second 

 joint of the antennular peduncle is not invariably four. Quite a number of the 

 specimens in this additional material have only three spines in this position. The 

 main interest centres in the form of the exopod of the third pleopods of the male. 



1 There is apparently some variation in this character. 



