298 



Records of the Indian Museum. 



[Vol. XIIL 



In the first peraeopods (text fig. la) the carpus is compara- 

 tively slender, from 2*2 to 2-5 times as long as its greatest breadth ; 

 rarely in young specimens the proportion falls as low as i-8. The 

 chela is about a third longer than the carpus and its length is usual- 

 ly about one-third the width of the palm. The carpus of the 

 second pair (text fig. 16) is from 6"o to yi times as long as broad. 

 The dactylus of the third peraeopods (text-figs, ic, d) is long and 

 slender; the propodus is only from 2"-i to 2"5 times its length. 

 Excluding the spines its length is from 37 to 4"5 times its breadth. 

 The dactylar spines vary in number from 19 to 22, very rarely 

 18. In the fifth peraeopods (text figs, le, /) the propodus is also 

 from 21 to 2 "5 times as long as the dact3dus ; the latter segment 

 bears from 43 to 69 spinules, excluding which it is from 4-2 to 4-8 

 times as long as broad. 



In the male the propodus of the third and fourth peraeopods 

 is a little dilated towards the distal end and the terminal third of 



Fici. I. — I'di-afya compressa ( de Haap). 



a. First peraeopod. d. Dactylus of third peraeopod. 



/). Second peraeopod. e. Fifth peraeopod. 



c. Third peraeopod of male. /. Dactylus of fifth peraeopod. 



the posterior margin is armed with numerous close-set spines (text- 

 fig, ic). In the specimens I have seen these sexual modifications 

 are much less conspicuous than in the larger individuals belonging 

 to the subsp improvisa. 



None of the specimens examined bear eggs ; the largest is 23 

 mm. in total length, 



De Haan's figure of this species is unusuall}^ poor, but except 

 for the fact that the carpus of the second legs is stated to be in- 

 distinctly annulate, the description agrees very well with the speci- 

 mens I have examined. According to de Haan there are 20 to 

 24 teeth on the upper border of the rostrum. 



The typical form of P. compressa is represented in the Indian 

 Museum by a great number of specimens collected by Dr. Annan- 

 dale in Komatsu Lake near the eastern shore of Lake Biwa and 

 from the Ogura and Yodo ponds near Kyoto : there are also a few 

 examples from L. Biwa itself. All specimens from localities situ- 



