OSTREA OYSTER, SCALLOP, 179 



Genus OSTREA.* (PZwraZ, Ostrecs.) 



OYSTER, SCALLOP, OR PECTEN. 



Generic Character. Shell bivalve, generally 

 inequi valve, inequilateral, more or less eared ; 

 hinge without teeth, having an ovate sinus, in 

 which is fixed an elastic cartilage, and generally 

 lateral transverse grooves. 



OBSERVATIONS ON THE SHELL AND ITS 

 INHABITANT. 



This genus contains shells very different in 

 their general appearance, but united by the 

 peculiarity in the hinge, which is toothless, and 

 has an elastic cartilage inserted into a sinus. It 

 may be divided into two families, the Pecten or 

 Scallop, and the Oyster,* which are separated 

 by very marked distinctions. 



The Pecten is of a regular orbicular form, 

 and eared ; its surface is adorned with diver- 

 gent ribs, which proceed from the apices to 

 the circumference, where they terminate in a 

 scalloped margin. The shells of this division 

 usually display brilliant colours. 



The second division contains the species more 

 or less resembling the common oyster; these 



* Plate IX. figures 7, 8: 

 N 2 



