XII. NOTE ON THE OCCURRENCE IN THE 



RIVER GANGES OF THE AMPHIPOD, 



AM PE LI SC A PUSILLA SARS. 



By Dr. Chas. Chilton, Canterbury College^ New Zealand. 



Some time ago I received from Dr. N. Annandale a tube con- 

 taining some Amphipods collected in the river Ganges at Buxar, 

 about 600 miles from the mouth, by T. Southwell, Esq. These 

 were sent for comparison with the Amphipods from the Chilka 

 Lake Survey which I was then examining. The specimens from 

 Buxar proved to be /I ;;z/)e//sca piisilla Sars, a species which was 

 also represented by many specimens from several localities in 

 the Chilka Lake. This species was originally described by Sars ' from 

 the seas off the coast of Norwa}' at depths from 180 to 370 metres. 

 These northern specimens had the eyes imperfectly developed, 

 without any trace of the corneal lenses. In 1910 Stebbing* with 

 some hesitation referred to this species a single specimen oljtained 

 by the " Thetis " off Wata Mooli on the east coast of Australia, but 

 stated that in this specimen the corneal lenses appeared to be 

 present. They are also present in the specimens both from the Chilka 

 Lake and from Buxar, but from the very close resemblance in all 

 other respects of the specimens, both male and female, to the 

 descriptions and figures given by Sars, I feel quite confident that 

 they are rightly referred to Ampelisca pusilla. The imperfection 

 in the eyes of the northern specimens is probably to be associated 

 with their occurrence at considerable depths in the ocean. In the 

 specimens from Buxar the eyes in most of the specimens were 

 distinctly red, though they had been for a considerable time in 

 spirit, in some the whole ej^e with its two corneal lenses being red, 

 in others the red colour being somewhat patchy. 



As I have stated in my report on the Chilka Lake Amphipoda * 

 I think Ampelisca chevreuxi Walker from Ceylon should be con- 

 sidered as a synonym of A mpelisca pusilla. 



So far as I am aware, the numerous species of Ampelisca 

 have hitherto been recorded from marine localities only, and the 

 occurrence of this species in fresh water in the river Ganges seems 

 therefore worth}^ of a special note. In the Chilka Lake it occurs at 

 several localities at some of which the water is probably brackish or 

 perhaps quite fresh at certain seasons of the year. 



• Crustacea of Norway, I, Amphipoda, p. 181, pi. 63, fig. 2. 



2 Amphipoda of "Thetis" Expedition, Australian Museum Mem. IV, 

 P- 576. 



3 Mem. Ind. Mus. V {in t lie press). 



