1 92 1.] Fauna of the Chilka Lake : Amphipoda. 537 



Quadrivisio bengalensis, Stebbing. 

 (Text-fig. 6.) 



Quadrivisio bengalensis Stebbing, 1907, p. 159, pi. 7. 

 Quadrivisio bengalensis Chevreux, 1913, p. 15, fig. 1. 



Localities : — 



Off Samal Island, 8-15 ft., 22-ix-i3. Many specimens, males and females, 



the largest about 12 mm. in length. 

 Off Barkul, 3-4 ft. Two specimens. 

 Off Satpara, 4-5 ft., i7-ix-i3. One specimen. 

 Ghiakhala Headland and neighbouring island. Four specimens. 

 Main Channel, W. of Satpara Island. Four specimens. 



Fig. 6. — Quadrivisio bengalensis. 

 a. First gnathopod of female. b. Second gnathopod of female. 



c. Telson. 



I have compared these specimens both with Stebbing' s description and with a 

 co- type of his species from Port Canning, and consider that they should be referred 

 to the same species although in one or two points they show slight differences. The 

 antennae differ very much in the two sexes, the peduncle of the lower one in 

 particular being greatly elongated in the adult males. The widely spaced pair of 

 denticles on the dorsal surface of the pleon segments are quite distinctly to be made 

 out in adult specimens from Chilka L,ake; in Stebbing' s specimens they are said to 

 be very small and difficult to observe. The main difference appears to be in the 

 telson, Stebbing' s figure is probably from a slightly abnormal specimen for it shows 

 the two halves distinctly unlike, the right being shorter and more rounded at the 

 end than the left half and with a different armature of setae. In specimens I have 

 examined both halves are alike (fig. 6c) and in general shape resemble the left half 

 of Stebbing' s figure, narrowing towards the extremity, but they bear fewer setae, 



