60 BIV^ALVES. — OSTREA. 



Family 6, — JPlth an ear- shaped appendage in the interior of 



each valte. 



Concamerata — Chambered. 



Division II. — With the teeth of the hinge in a 



CURVED LINE. 



Family 1. — Subcordate. 

 Campechensis — Campeachy. ^quilatera — ^Equilateral. 



A ngulosa — Angular. 



Family 2. — Suborbicidar, margins crenated or plaited. 

 Pectunculus — Spotted. *Glycymeris — Orbicular. 



Pectinata — Covib. *Pilosa — Downy. 



Decussata — Dectissated. Stellata — Starred. 



Fallens — 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, hut 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. 



