IÇ)I5-] Fauna of the Chilka Lake : Crustacea Decaftoda. 207 



Ebalia malefactrix. Scylla sen ata. 



Ocypoda macrocera. Clibanarius padavensis. 



Gelasimus annulipes. Clibanarius longitarsis. 



Pachygrapsus propinquus. Clibanarius olivaceus. 



Varuna litter ata. Diogenes avarus. 



Camptandrium sexdentatum. Urocaris indica. 



Sesarma batavicum. Periclimenes demani. 



Cardiosoma carnifex. Ogyrides striaticauda. 



Heteropanope indica. Alpheus malabaricus. 



Leipocten sordidulum. Penaeus carinatus. 



Penaeopsis dobsoni. 



M etasesarma rousseauxi, Sesarma quadratum and Neptunus sanguinolentus , com- 

 mon and characteristic species in the Madras backwaters, are absent from the Chilka 

 Lake. 



It is noteworthy that a considerable number of the species in the above list are 

 known only from Indian backwaters, whereas the majority of those common to the 

 Chilka Lake and the Gangetic delta are widely distributed forms. Ebalia malefactrix 

 and Ogyrides striaticauda have also been found in the Cochin backwaters on the south- 

 west coast of India. 



As far as the Decapods are concerned, therefore, the lake fauna shows a much 

 greater resemblance to that of the Madras backwaters than to that of the Gangetic 

 delta, and this fact is also illustrated by other groups of animals. 



Owing to the fact that our survey of the lake fauna was, in the main, restricted 

 to one year, our observations on the periods at which the different species breed are 

 unfortunately very incomplete; but in a few instances the evidence is interesting. 

 On the Indian coasts in February and March females of the great majority of littoral 

 marine Decapoda are to be found bearing eggs and, inasmuch as the water of the 

 lake is at this period almost at its maximum salinity, it would naturally be supposed 

 that species usually marine, or closely related to marine forms, would breed at this 

 season. In several instances, however, this is certainly not the case. 



Only of five species (all of them forms found in the outer channel, but absent 

 from the main area) were ovigerous females obtained solely in water as salt as that 

 of the Bay of Bengal (sp. gr. 1 0265). These are : — 



Dotilla pertinax. Ogyrides striaticauda. 



Diogenes avarus. Athanas dimorphus. 



Alpheus malabaricus. 



As far as our observations go, seven species breed in water that is strongly saline 

 or brackish, but were not found bearing eggs in fresh water. The names of these 

 species are as follows, the specific gravities of the water in which ovigerous females 

 were found being added in brackets: — 



