1921.] Fauna of the Chilka Lake : Amphipoda. 547 



the first gnathopod of the male and in both the first and second gnathopods of the 

 female is smaller and narrower than in the Indian Ocean specimens. This is shown 

 by Walker's figure of the first gnathopod of the male of H. brevipes and in those 

 which I now give of the first and second gnathopods of the female (figs. gd,e). In the 

 European specimens the setae on the hind margin of the propod form a rather dis- 

 tinct tuft near the middle, while in the Lake Chilka specimens they form a continuous 

 row from the base nearly to the palm ; this character is perhaps not constant, for 

 Stebbing describes H. prevostii as having the hind margin of gnathopod 1 of male 

 "with spinules from the base to a submedian spine." 



Again, in the European specimen the posterior margin of the basal joint of 

 peraeopods 3-5 is described by Stebbing as being smooth, whereas in the Lake Chilka 

 specimens it is distinctly, though not conspicuously, serrated (fig. 9/). I find, 

 however, that though the hind margin in the European specimens is on the whole 

 smooth, there are slight indications of serrations on some of the peraeopods. 



In the Lake Chilka specimens the palm of the second gnathopod of the male is 

 slightly convex, about the same as in the European specimens, though in the 

 Minikoi specimens, Walker describes it as being "almost straight." Another 

 diagnostic point, not mentioned, however, by Walker, is the presence or absence of 

 setae on the hind margin of the sixth joint of peraeopods 4 and 5. Stebbing des- 

 cribes H. prevostii as having a "group of setae and spine at middle of hind margin." 

 In the Lake Chilka specimens there is usually one rather fine seta and sometimes 

 more ; on the other hand in the European specimens that I have at my disposal, the 

 hind margin is quite free from setae and spines. 



The specimens from the Azores described under the name of Hyale prevostii by 

 Chevreux (1908, p. 7, pi. i, fig. 3) seem on the whole to be almost the same as the 

 Chilka Lake specimens. They agree in the points mentioned above for the gnatho- 

 poda and also fairly well in the characters specially mentioned by Chevreux in 

 connection with the antennae, the eyes and the rigid spine on the dactyl of the last 

 five peraeopoda. The eyes in the Chilka specimens are certainly large, especially in 

 the male, and irregularly oval or in some cases almost reniform ; the spine on the 

 dactyl of the peraeopoda is also present, but rather less marked than is shown in 

 Chevreux' s figure. The Chilka Lake specimens are, however, all smaller than those 

 from the Azores described by Chevreux, none of them being more than 7 mm. in 

 length, while Chevreux' s male specimens were as much as 11 mm. long. 



In one male specimen examined, the second antenna (figs, gb and c) on one 

 side was abnormal ; it had apparently been injured and was much shorter than its 

 fellow and had only seven joints in the flagellum and these somewhat irregular. 

 More striking, however, was an abnormal appendage at the upper distal end of the 

 penultimate joint of the peduncle. This looked at first almost like the accessory 

 flagellum of species in which such a flagellum occurs, but was apparently composed 

 of a single joint only, slightly wider towards the base than near the apex, the apex 

 being rounded, slightly enlarged and bearing two or three fine setae. The integu- 

 ment was chitinised like an ordinary joint of the flagellum, and the whole append- 



