60 



CEYLON PEARL OYSTER REPORT. 



Around such hard patches the bottom is all sand, in some parts coarse, in others 

 finer, and varying in constitution from almost pure quartz to a neritic deposit formed 

 mainly of the shells of Foraminifera {OvUtolites, Heterostegina, Alveolina, &c). On 

 the sand fewer oysters are found, but they cannot be said to be absent, especially in 

 the neighbourhood of a "paar" (or hard patch). When present they are generally 



Fig. 10. Our two divers on the 

 " Serendib." 



Fig. 11. Young pearl oysters, about six months old, 

 attached to a dead Madrepore Coral. 



united in clumps of several fastened together by their byssus threads or attached by 

 si niie hard object such as a Nullipore nodule, a dead shell or a fragment of coral. 

 In some cases two or three large oysters (about 3 years old) will form a centre upon 

 which a great many young ones (about 6 months old) are fastened (fig. 12). In 

 some places there is undoubtedly overcrowding, the larger oysters being completely 

 surrounded with masses of young piled so closely as to smother some and probably 

 interfere with the growth of all. This is a precisely similar case to that of the 

 overcrowding found in European mussel beds, where the advantage of thinning out 

 and transplanting is well known. 



We got the divers to construct for us, after several dives to verify the details, a 

 model on the deck of the " Serendib" showing the distribution of oysters on the rock 

 and sand at the bottom. Fig. 12 is from a diagrammatic drawing (in bird's-eye-view) 

 showing what they produced.* 



Although oysters lying on the sand may manage to survive for a time, especially if 



* These and our other conclusions in regard to the configuration and constitution of the paars and the 

 distribution of the pearl oysters were verified later on by Mr. Hornell when, at the fishery in the 

 spring of 1903, a European diving costume being available, he was enabled to make a personal inspection 

 of the bottom. 



