oct.— dec. 1857.] The Pearl Oyster of Ceylon. 



91 



I have carefully examined Oysters of all ages, and have no- 

 ted the structure of the shell, and of the animal within it : which 

 will form the subject of illustration in a future Report. In this, I 

 shall briefly describe the animal ; as it is of the greatest importance, 

 that a correct knowledge be first obtained of the animal structure, 

 before a physiological account of its habits can be properly un- 

 derstood. 



Meleagrina margaritifera, Lamarck. Mytilus margaritiferus, Linn. 

 Pearl Oyster, Eng. Avicula radiata, Leac/t. 



Pintadine mere perle, Fr. „ margaritifera, Sowerby. 



Mutu Cliipi. Tam. & Syng. „ meleagrina, Blalnville. 



Conchologists have long agreed, that Lamarck was right in sepa- 

 rating the " Pearl Oyster ," par excellence, from the old genus Avi- 

 cula, of which there are several species in Ceylon, some producing 

 valueless pearls of a dusky blue and blackish colour. The only de- 

 scription of the Pearl Oyster of Ceylon I have access to, is La- 

 marck's, in his " Histoire Naturelle des animaux sans Vertebres," 

 and that, too, is only of the shell. 



" Meleagrina, testa subquadrata, superne rotnndata,fusco virenie. 

 Albo radiata, lamellis per series longitadinalis imbricatis, superioribus 

 tnajoribus." — Lamarck, vol. 7, p. 107. 



The Ceylon shell is a variety of that above described. The 

 white radiating lines are alternated with rays of a red or black co- 

 lour. Doctor Templeton made it appear, that the Ceylon variety 

 corresponded with Leach's description of his Avicula radiata. I am 

 more inclined to believe, that they are only accidental or occasional 

 varieties. The shell however, appears to attain a larger size in Ame- 

 rica, and in the Persian Gulph, than in the Seas of Ceylon. In the 

 largest Ceylon shells, the red or black radiating lines become obso- 

 lete. If they are permanent varieties, they are both found in Cey- 

 lon. I have a faint recollection of having seen both varieties on the 

 Pearl banks of Arripo. 1 had also a small perfectly white Pearl 

 Oyster ; this may be an Albino specimen or Lamarck's Meleagrina 

 albina. M. testa albida, irradiata, obsolete squamosa; aiiriculis 

 duabus semper distinctis, originally found on the coasts of New Hol- 

 land and Van Diemen's Land. 



