I 9 2I.] 



Fauna of the Chilka Lake : Amphipoda. 



539 



In the short antennae (figs, ya, b) thickened in the males, and in the gnathopods 

 (figs, yc, d) and other appendages they seem to agree very closely with Dana's 

 species as described by Stebbing in 1906, and they certainly correspond with other 

 specimens in my collection from Tonga which I had also referred to this species. 

 Among the Chilka Lake 

 specimens there were only 

 a few males and probably 

 not more than one quite 

 fully developed ; the second 

 gnathopod of the largest 

 and presumably the oldest 

 one is represented in figure 

 yd and shows two low 

 convex spinulose processes 

 as described by Dana, 

 though these are both 

 about the same breadth. 

 Stebbing in his figure of a 

 male of 0. pickeringii 

 from the Hawaiian Islands 

 shows the processes on the 

 palm more separated and 

 more pronounced, with the 

 finger thickened about the 

 middle, but as he points 

 out, in younger specimens 

 the inner margin of the 

 finger is smoothly concave. 

 Later on I had occasion 

 to examine and mount 

 some specimens sent to me 

 from Cold Spring Harbor, 

 U.S.A. as 0. agilis S. I. 

 Smith, a species which 

 Stebbing unites with 0. 

 platensis, and I was struck 

 by the resemblance of them 

 to the Chilka Lake speci- 

 mens. After careful comparison I can find no difference between the Cold Spring 

 Harbor and the Chilka Lake specimens except in the character of the palm of 

 the second gnathopod in the adult male and I therefore feel pretty confident that 

 the Chilka specimens should be referred to 0. platensis and that the two species 

 0. platensis and 0. pickeringii will have to be combined. After coming to this 



Fig. 7. — Orchestia platensis, male. 



a. First antenna. c. First gnathopod. 



b. Second antenna. 



d. Second gnathopod. 



