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JOURNAL, R.A.S. (CEYLON). [VOL. XVI. 



have been fairly maintained during my time. No silting up 

 or upheaval in their neighbourhood can be detected by the 

 soundings, which have not decreased during the last seventy 

 years. Changes, however, are taking place on the shore in 

 that neighbourhood. The cliff opposite the " Doric " is 

 gradually washing away, and much of the island of Karaitivu 

 has disappeared since I first knew it. On the other hand, the 

 spit forming the western side of Dutch Bay has been extended 

 into the sea in a north-east direction about one mile during 

 the last forty years. 



Enemies of the Pearl Oyster and Currents. 



The enemies of the pearl oyster are no doubt many, as it 

 seems to be the nature of all animal life in the sea to prey 

 upon each other ; but the chief ones to be feared and 

 destroyed, if possible, are the various species offish that feed 

 on the bottom, and for that reason are commonly called rock 

 fish. These, with the exception of skate, are however only 

 destructive to the pearl oysters when they are young and 

 their shells tender, say up to the age of eighteen months or 

 two years, after which age the smaller kinds of rock fish, 

 which appear to be most numerous, do not do much harm. 



Generally speaking, when I have been at anchor on a bed of 

 young oysters the crew of the vessel have caught many rock 

 fish, the stomachs of which were found to contain many 

 fragments of the young oyster shells, thus proving the source 

 of their food. 



A bed of young oysters no doubt attracts these rock fish, 

 which appear to come on it in great swarms, and although 

 the young oysters are very numerous, and are generally very 

 thickly spread over large areas — I have counted as many as 40 

 attached to the fragment of an old oyster shell — yet their 

 enemies are numerous also, and are capable of causing much 

 destruction, often completely annihilating the whole bed, 

 leaving not a vestige behind when I visit the bank a year 

 later ; so that if some means could be devised of destroying 

 or keeping these rock fish away from a bank of young oysters 



