60 BIVALVES. OSTREA. 



FAMILY 6. With an ear-shaped appendage in the interior of 



each valve. 

 Concamerata Chambered. 



DIVISION II. WITH THE TEETH OF THE HINGE IN A 



CURVED LINE. 



FAMILY 1. Subcordate. 



Campechensis Campeachy. ^Equilatera ^Equilateral. 

 A ngulosa Angular. 



FAMILY 2. Suborbicular, margins crenated or plaited. 

 Pectunculus Spotted. *Glycymeris Orbicular. 



Pectinata Comb. *Pilosa Downy. 



Decussata Decussated. Stellata Starred. 



Pallens Pale. Scripta Lettered. 



Undata Lettered. Nummaria Coin. 



FAMILY 3. Suborbicular, margin entire. 

 Multis-striata Many-striped. 



DIVISION III. WITH THE TEETH OF THE HINGE PRODUCED 



AND SHARPLY POINTED. 



*Nucleus Silvery. *Minuta Small. 



*Rostrata Beaked. *Tenuis Thin. 



OSTREA. OYSTER AND SCALLOP. 



Animal a Tethys : Shell bivalve, generally with unequal 

 valves, and slightly eared ; hinge without teeth, but fur- 

 nished with an ovate hollow, and mostly lateral transverse 

 grooves. 

 THERE are no less than eighty-eight species in this 



genus, which present considerable variety in beauty and 



form. 



