88 Drs. Kelaart and Mobius on the Natural History of 



and in places so shallow that it must be exposed for three or 

 four hours daily to the sun and other atmospheric influences." 



Taking all these circumstances into account, there seems to 

 be every foundation for the hope expressed by our author, that 

 the Pearl Oysters may be successfully transferred from their 

 native beds, and made to colonize other parts of the sea. His 

 experiments, indeed, appear to be conclusive upon this point. 

 He says : — 



"I have successfully established a colony of Pearl Oysters 

 near Fort Frederick, in the open sea, at various depths; and 

 have also oysters which have been living for several months in 

 wooden boxes, finger-glasses, glass globes, chatties, and large 

 canoes, sunk in the sea. Some were thrown into the sea, after 

 being removed from the inner harbour and kept in my house in 

 chatties and tubs for two and thi'ee days. The byssus of most 

 of them had been broken and torn from the rock. These they 

 have cast off", and are now living attached to each other, and to 

 pieces of coral, and to rocks, exposed to all the influences of the 

 sea." 



Of the general habits of the Pearl Oyster Dr. Kelaart speaks 

 as follows : — 



" The whole occupation of the Oyster, when fixed to a spot, 

 appears to be, keeping its valves open and admitting food to its 

 mouth. For several hours the valves remain open, they then 

 close for a few minutes, or for an hour or two, then open again. 

 At night, the valves remain generally open till towards daylight, 

 when they close, and remain so till the sun shines brightly over 

 the horizon. It is during the early part of the night, or soon 

 after sunset, that they exercise, when required, their locomotive 

 powers. I have watched the oysters in aquaria for nearly a 

 whole night ; and they appear to be then active in moving and 

 attaching themselves to new localities. During the day 1 have 

 only seen on one occasion an oyster form a new byssus. This 

 nocturnal habit is, doubtless, an instinctive precaution ; for 

 should oysters move during the day, they are more likely to 

 become the food of fishes and other animals which prey upon 

 them. Their movements are instinctive, and guided by the 

 sense of touch. Darkness suits them better than daylight, of 

 the difference of which they are very sensitive." 



The Tamhlegam Pearl Oyster. 



It is well known that, besides the true Pearl Oyster, many 

 other species of Mollusca produce perfect pearls, some of which 

 possess considerable lustre. Amongst these is the Common Oyster 

 [Ostrea edulis, L.), which sometimes contains good pearls, as in 



