ORDER UNIMUSCULOSA. 69 



into use among ladies, who employ it in making pin- 

 cushions and other articles of fancy-work ; there are 

 about sixty recent, and thirty fossil species. 



Ihe power of locomotion appears to be very con- 

 siderable in some species of the Peciens; it is said the 

 animal can raise il&elf up in the water, and even reach 

 the surface, by moving the two valves of its shell ; but 

 this is a iact not quite established, as but little is known 

 of its habits. It is sometimes used as an article of food; 

 but to reader it tolerably palatable it requires cooking. 



In some countries, the shells of the larger species are 

 used by the poorer classes instead of plates. In Paris, 

 the restaurateurs employ them for the same purpose 

 when serving up a certain preparation of mushrooms; 

 in England, they are employed in cooking scalloped 

 oysters, and the shell is consequently known as the 

 Scallop Shell. 



The Pearl Oyster, {Meleagrina margaritifera.) 



The animal of this shell, although popularly called an 

 oyster, is very different in structure, bearing greater 

 resemblance, in some parts of its formation, to the mus- 

 sel, particularly in possessing a byssus^ or beard ; it is 

 the shell in which the famous oriental pearls are found. 

 There are but two known species of the IMeleagrina, 

 which are chietly fouud in the Persian Gulf, and at 

 Ceylon, or in some of the seas of Australasia. 



The cause of the formation of pearl in the shells of 

 this and other inhabitants of the water, has been the 

 occasion of considerable dispute, but it is now pretty- 

 well ascertained. 



The inner portion of the shell of the Meleagrina is 



