oct. — dec. 1857.] Pearl Oyster Fishery. 



105 



ence, are required, to ascertain the results of this practice in Cey- 

 lon. Dr. Gray, of the British Museum, has, I believe, by the ap- 

 plication of the same means, succeeded in producing Pearls in the 

 edible Mussel or Oyster of England. It may therefore be hoped 

 that I shall eventually succeed with the Pearl Oyster of Ceylon. 

 All that I can at present say, is, that they do not die under the 

 operation, and that they are still living, having also reformed new 

 byssuses. This is the only way the period required for the forma- 

 tion of good sized Pearls can be ascertained. There are some 

 other points in the natural habits of the Pearl Oyster, which I re- 

 serve for future Reports, as precipitate conclusions may mislead 

 the Government. 



X. Report on the Tamblegam Pearl Oyster Fishery. By 

 E. F. Kelaart, m. d. 



The Oyster found in the Tamblegam lake, and from which Pearls 

 are obtained, is the Placuna placenta, " Vitre Chinoise'' of some 

 French writers, and the " Window Oyster" of English travellers 

 in China — the shells, from their semi-transparency, being used for 

 windows. The Placuna belongs to the same family of Conchifer- 

 ous Molluscs as the edible Oysters of Europe and of this country. 

 It has no resemblance (except slightly in the animal structure), 

 to the shells of the Arripo Oyster (Meleagrina.) When full grown 

 the valves (shells) measure, at their broadest transverse diameter, 

 from 5 to 7 inches ; and their longest longitudinal diameter is about 

 the same ; some, half an inch more. They arrive at maturity soone r 

 than the Maleagrina margaritifera, and like the Aripo Pearl Oys- 

 ter, the young also have ova. I am not able from my own obser- 

 vation (having been only a few months engaged in these researches) 

 to say, in how many years this Oyster arrives at perfection. 



