CHAPTER IX. 



VARIETIES OF OYSTERS. 



CLASS CONCHIFERA (CONTINUED). 



THE PECTINID^E GENUS PECTEN PECTEN PUSIO PECTEN VARIUS 

 -PECTEN OPERCULARIS PECTEN SEPTEMRADIATUS PECTEN 

 TIGRINUS PECTEN TESTAE PECTEN STRIATUS PECTEN SIMILIS 

 -PECTEN MAXIMUS HAMMER-HEADED OYSTER. 



Family III. PECTINID^E, Lamarck. 



BODY oval or oblong, compressed : ?nantle having 

 thick edges : cirri long and extensile : gills reflected : foot 

 developed. 



SHELL spade-shaped, usually inequivalve and inequi- 

 lateral : beaks small, straight, and pointed, with lateral 

 triangular processes like ears or wings : hinge toothless : 

 cartilage internal, placed in a cavity beneath the beaks and 

 strengthened by a narrow ligament on each side. 



The animal has a distinct foot, which is capable of 

 spinning a byssus, or bundle of horny threads, for attach- 

 ment to other bodies. It is also endued with a peculiar 

 power of locomotion. By a muscular action, analogous to 



