OF CONCHOLOGY. 59 



dicular furrowed line, as in the spe- 

 cies of Perna. The first family is 

 again subdivided into three sections: 

 fvalves sequilateral, and ears equal ; 

 'hears unequal, and having one of them 

 generally ciliated with spires within; 

 t1 t^alves gibbous on one side. 



Habitation. The Ostrea have only 

 been found in the ocean ; some lurk 

 in the sand in large beds, others ad- 

 here to rocks, and some to trees on 

 the shores of the West Indies, &c. 



The Ostrea might with great pro- 

 priety be divided into two species, 

 scallops and oysters, as those sections 

 are very dissimilar. 



The French Naturalists have formed 

 this genus into seven : Ostrea, Pec- 

 ten, Malleus, Perna, Lima, Pedum, 

 and Gryphus. 



In Turton's Linne 137 species are 

 described ; nine species are found in 

 the British seas. 



