AMPHIPODA. 



By Chas. Chilton. 



INTRODUCTION. 



The number of species of Amphipoda collected from Chilka Lake is not great, 

 comprising only seventeen (17) species, but the collection is nevertheless of very 

 considerable importance and interest. Most of the species were gathered at many 

 different localities and often in very great numbers. They are nearly all of small 

 size and in several cases the task of sorting them out and of distinguishing allied 

 species was somewhat laborious. Most of the specimens have been referred to species 

 already known, but I have had to establish three new species. A considerable amount 

 of additional information is also given with regard to species previously described. 



Several questions of interest arise with regard to the distribution of the species. 

 Thus Ampelisca pusilla Sars, which was originally described from deep waters in 

 Arctic Seas, is found in great abundance in the Lake. It also occurs in the river 

 Ganges at Buxar about six hundred miles from the mouth and had previously been 

 recorded from the east coast of Australia by Stebbing. The Indian specimens differ 

 from the Arctic in having corneal lenses present, but in all other respects agree very 

 closely with the Arctic forms. 



Quadrivisio bengalensis Stebbing, originally described from Port Canning, Lower 

 Bengal, evidently occurs in great abundance in some parts of the lake. It is found 

 also in the island of Zanzibar, East Africa, and Dr. Annandale has sent me specimens 

 from four different localities in the Talé Sap, Siam. 



Grandidierella megnae (Giles) seems hardly distinguishable from G. maha/alensis 

 Coutière from Madagascar. The original specimen from which Dr. Giles described 

 the species was taken at Megna Shoals, Bay of Bengal. In this species there appear 

 to be two forms of the male, differing from one another in the characters of the first 

 gnathopod. An allied form which agrees with most of the characters of Grandidi- 

 erella megnae except in the second gnathopods, is described below as a new species, 

 G. gilesi sp. nov. 



Melita inaequistylis (Dana) is a very widely distributed species occurring in India, 

 South Africa, New Zealand, etc. 



Perhaps the most striking example as regards the geographical distribution of 

 the Chilka Lake Amphipoda is the species Paracalliope fiuviatilis (G. M. Thomson). 

 This species was described many years ago from New Zealand, where it is the common 

 form occurring in nearly all freshwater streams, though it is also found in brackish 

 waters and sometimes in water that is perfectly salt. It is evidently abundant in 



