3i6 Memoirs of the Indian Museum. [Vol. V, 



More recently the ( Investigator ' found the species in large numbers in the Mergui 

 Archipelago (lat. n°58 , 20 ,/ to I2°48' N. ; long o^iô'io" to 98°26'3o" E.) at depths 

 varying from 8 to 24 fms. During the present year I found a number of specimens, 

 mostly on a muddy bottom, at Port Blair in the Andamans in from 1 to 10 fms. and 

 in 1913 obtained a few examples in shallow water among weeds at Kilakarai in the 

 Ramnad District at the northern end of the Gulf of Manaar. 



The species has hitherto been recorded only from the Red Sea. 



Tribe PENAEIDEA. 

 Family PENAEIDAE. 



Five species belonging to this family occur in the Chilka Lake. Four of them 

 are abundant and are caught in large numbers by the Uriya fishermen in special 

 traps, which will be described in a subsequent paper in this volume. The trap depends 

 for its efficacy on the habits of the prawns, which travel at night along the shore in very 

 shallow water. If they meet with any obstruction they make their way along it and 

 are thus, by means of training fences, easily led into an enclosure surrounded by 

 traps, into the apertures of which they apparently force themselves on the approach 

 of daylight. On Barnikuda I. there is a factory in which Penaeid prawns are 

 dried for export, the greater part of the supply finding its ultimate destination in 

 Burma. 



The little knowledge we at present possess of the prawn fisheries in the Gangetic 

 delta tends to show that there is an annual migration of Penaeidae to the sea. This 

 migration takes place in the winter months and apparently coincides with the begin- 

 ning of the breeding season. 1 In the Chilka Lake we found no clear evidence of 

 migrations ; three at least of the species are found throughout the year, but it is toler- 

 ably certain that none of them breed in the lake. The shallow waters of the main 

 area with the dense beds of weed that exist in many parts would seem to afford an 

 admirable nursery for young Penaeids. In such localities, however, we failed to 

 find them : all the young specimens in our collection were obtained in the outer chan- 

 nel. It is only to adolescent prawns that the main area of the lake is attractive ; 

 early post-larval stages are seemingly unable to withstand the changes in salinity, 

 while the fact that no very large specimens were obtained (though individuals with 

 well-developed secondary sexual characters are not uncommon) tends to show that 

 after they have returned to the sea for breeding purposes they do not again re-enter 

 the lake. 



Thanks to Alcock' s memoir on the Indian prawns of the Penaeus group, the 

 characters of most of the Indian species are now well known ; but more recent work 

 has unfortunately made necessary a number of changes in the nomenclature that he 

 adopted. 



1 On the British coasts somewhat similar migrations are known in the case of Pandalus montagui 

 [v. Kemp, Fisheries, Ireland, Sei. Invest, for 1908, p. 87 (1910)]. 



