86 MADRAS FISHERIES BULLETIN [VOL. XVI, 



and after trying various places found a small bed of the living 

 animal and brought ashore a considerable number. The majority 

 of them were fairly well grown and approaching maturity. The 

 size of six typical individuals averaged 15% centimetres in 

 diameter, being almost perfectly circular in outline. 



The men also reported large numbers of dead shells which, 

 however, probably belong to past generations. 



Placuna lives well out of water for some time if kept in a cool 

 situation, a property due to the faculty this shell-fish possesses of 

 closing the valves tightly at all points round the margin, after the 

 fashion of the edible oyster. In this particular case, several 

 individuals which I put on one side for this experiment were found 

 alive and vigorous thirty hours later, in spite of being drained of 

 water and the temperature as high as 96° F. in the shade. 



In Ceylon a fishery of this shell was frequently leased by 

 Government with considerable profit during the past century, the 

 locality being an extensive shallow muddy bay on the north-east 

 coast, close to the harbour of Trincomali. 



In Tuticorin I could glean no information as to whether a fishery 

 had ever been held in the neighbourhood ; in view of the presence 

 of living individuals and of the great piles of embedded shells 

 along the sea-shore it might prove to be of advantage to Govern- 

 ment if further search were made in suitable localities — back- 

 waters, shallow estuaries, etc. — along the coast of the Madras 

 Presidency with a view to locate any beds sufficiently large to 

 provide a fishery and to ascertain also if pearls be sufficiently 

 numerous to make such a fishery profitable. I notice that Mr. 

 Edgar Thurston* records Placuna from Pulicat lake and Bucking- 

 ham canal. The former of these has, I understand, an area far 

 exceeding that of Tampalakam Bay and should, therefore, receive 

 special attention.! 



The weather had now improved temporarily and it was decided 

 to spend two more days upon the banks, in order if possible to 

 provide me with an opportunity to make a diving descent upon 

 the Tolayiram Par, a matter which I considered to be of great 

 importance. 



* " Notes on the Pearl and Chank Fisheries and Marine Fauna of the Gulf of 

 Manaar," Madras, 1890, page 27. 



f Subsequent examination showed that these localities are not Sufficiently open to the 

 sea to support large beds. The occasional individuals found occur only adjacent to the 

 seaward openings or " ' ars." 



