272 Memoirs of the Indian Museum. [Voi,. V, 



grey. A broad and well defined pale streak extends along the dorsal surface of the 

 merus, ischium and palm and is especially distinct on the last segment. The other 

 legs are pale, slightly darker on the dactylus and at the distal end of the propodus. 



Adults of both sexes of this species were found not uncommonly in. the Chilka 

 Ivake in the months of September and November, when the water was fresh or very 

 slightly brackish. During the former month they were obtained in abundance at 

 Barkul, where they are trapped in large numbers by the fishermen. Specimens were 

 also found off Nalbano, near Barnikuda I., and in the vicinity of Arupatna in the 

 outer channel. In the last locality they were found on the banks among submerged 

 roots of screw-pines. The females found at this season of the year were bearing eggs. 



No adults of either sex were found at any other time of the year; but young 

 individuals were frequently met with in February and March round the rocks at 

 the foot of Ganta Sua, at Chiriya I. and at Barkul Point, in water of moderate 

 salinity (sp. gr. 1 009 — i*oii), and in the latter month were abundant at Satpara in 

 water as salt as that of the Bay of Bengal near the lake (sp gr. 1-0265). 



We are convinced that in this species — and the facts already brought forward in 

 reference to P. malcolmsoni tend to show that the same is the case with it also — the 

 prawns, when they have attained a certain size, leave the lake and, during the mon- 

 soon, resort to the flooded rice-fields and other bodies of fresh water to which ingress 

 is easy. In the freshwater season, probably that of the following year, they return 

 to the lake when the eggs of the females are ripe. At this period, in the case of 

 Palaemon rudis, adult males accompany the females, whereas in P. malcolmsoni it is 

 apparently only the latter sex that visits the lake at the breeding season. In the 

 last species impregnation of the ova probably takes place outside the lake before the 

 annual migration of the females has begun. 



Palaemon rudis is known from E. Africa, Mozambique, Madagascar and Ceylon. 

 The species is not uncommon in the vicinit}^ of Calcutta and is recorded by Henderson 

 and Matthai from Coconada and Madras. 



Palaemon scabriculus, Heller. 



1910. Palaemon scabriculus, Henderson and Matthai, Rec. Ind. Mus., V, p. 296, pi xvii, figs, ya-c, 

 pi. xviii, figs. ya-p. 



To this species I refer two specimens caught by fishermen near Rambha at the 

 south end of the lake. One of them, in which there is a marked inequality in the 

 second pair of legs, is, I believe, a young male; the appendix masculina, however, 

 is not developed and the large chelipedes only bear scanty hairs in place of the dense 

 felted coating found in adults. The other individual is a female. 



In the female the rostrum bears twelve teeth above and two beneath and 

 reaches a little beyond the end of the antennular peduncle. In the male there are 

 thirteen dorsal teeth and two ventral, the blade reaching only to the end of the 

 peduncle. The four proximal dorsal teeth, in both cases, are situated on the cara- 

 pace behind the orbit. 



