126 POPULAR CONCHOLOGY. 



at once a union of elegance and beauty hardly 

 to be surpassed amongst tlie bivalves. They 

 are found in the Indian Ocean, the Mediter- 

 ranean, and on the American coasts. 



The fossil genus Podopsis of Lamarck, is 

 joined by Deshayes to Spondylus, and also some 

 species of Plagiostoma. 



Family 5. — Ostreidce* 



This family comprehends the oyster tribe, 

 and the genera forming it are usually affixed 

 by one valve to stones or rocks ; some of the 

 shells are foliaceous. — There are four genera. 



82. — Ostrea. — Shell inequivalve, irregular, 

 flattened ; substance foliaceous ; bosses distant, 

 and very unequal, that of the lower valve be- 

 coming very large with age, upper valve 

 smallest; no teeth. — Animal, no foot. — 53 spe- 

 cies recent, and 82 fossil. 



Oysters have been found in most parts of 

 the world in abundance, although none have as 

 yet been discovered in the polar regions : they 



* Les OstraceeSf Lamarck. 



