BIVALVES.—OSTREA. 57 
OSTREA.— Oyster, SCALLOP, OR PECTEN. 
DESCRIPTION OF PLATE XIV. 
Di. I. —Fam. 1. Fig. 2. O. ziczac. 
Fam. 4. Fig. 1. O. pleuronectes. 
Drv. Il.— Fam. 1. Fig. 4. O. varia. 
Fam. 2. Fig. 6. O. obsoleta. 
Dr. 1V.— Fam. 2. Fig. 5. O. folium. 
Dw. V. == Fig. 3. O. isognomon. 
Shell bivalve, generally with unequal valves, and slightly eared ; 
hinge without teeth, but furnished with an ovate hollow, and usu- 
ally with lateral transverse grooves. 
THERE are no less than eighty-eight species in this 
genus, which present considerable variety in beauty and 
form. 
The Ostreze are divided into several classes: the 
first and second (which are the most important) com- 
prise the mmumerable varieties of escallops or scallop 
shells, and are distinguished from each other by the 
proportion of their ears. The first is, for the most part, 
composed of very elegant species; their form is usually 
regular, and their surface is adorned with elevated 
divergent ribs, varying in number from five to forty, 
which proceed from the tip of the beaks to the extre- 
mity of the margins, there terminating in a scalloped 
outline. 
The Scallops are usually equivalve, but a few, as the 
O. ziczac, O. jacobea, and others of the same family, 
have invariably the upper valve flat, and the lower 
convex. 
It is remarkable, that in many of the Scallops the colors 
