OSTRACEA. MOLLUSCA. OSTREA. 135 



rounded ribs, the depressed spaces being similarly rounded, and 

 about equal to the ribs in width ; loosely wrinkled concentrically 

 by fine lines of growth. Usual color a dusky or blackish horn- 

 color, with alternately darker and lighter zones. Ears two thirds 

 of the length of the shell, nearly equal, and crossed with small, 

 radiating ridges ; notch in the convex valve deep, and forming an 

 acute angle, or narrow slit. Interior shining, grooved to corre- 

 spond with the exterior ribs, the intervening spaces flat ; color 

 white, generally tinged with purple-brown about the hinge, and 

 around the margin, sometimes altogether of that color. Liga- 

 mentary pit small and shallow. Length 2f inches, height 2J in- 

 ches, breadth I inch. 



The scoUop-she.il is found abundantly about the extremity of 

 Cape Cod, though it does not extend far along its inner shore. 

 It is common along all its outer shore, at Nantucket, Martha's 

 Vineyard, &c., and, according to Mr. Say, is one of the most 

 common shells along the shores of New Jersey. 



It is subject to great variation in coloring. The flatter valve is often 

 white, and always of a lighter color than the other valve. Sometimes 

 both valves are white, orange, ochreous, reddish, or purplish, and 

 sometimes they are zoned or mottled with two or more of these colors. 

 In consequence of which they are very pleasing to the eye, and are 

 extensively employed in the manufacture of card-racks, pincush- 

 ions, &c. 



FAMILY OSTRACEA, LAM. 



Shell irregular, foliated, sometimes paper-like ; ligament internal or partly 

 internal. 



GENUS OSTREA, LIN. 



Shell very irregular, inequivalve, the larger one adhering, the 

 smaller moving forwards as the shell advances in age, and leaving 

 a lengthening groove for the ligament exposed along the beak of 

 the adhering valve. 



The Oyster varies in surface and shape so much, according to 

 the position in which it lies during growth, that it is not only im- 

 possible to give any description which shall delineate the various 



