UMBO 



HINGE AXIS 



WIDTH 



Figure 19. — Several generations of oysters, C virginica, 

 growing vertically on muddy bottom of Altaniaha 

 Sound, Ga. Notice the very long and narrow beak of 

 the lowermost shell. 



Figure 20. — Diagram showing the correct method of 

 measuring the height, length, and width of oyster shells. 



for instance, in any part of the coast where 

 oysters grow singly on hard bottom and are not 

 crowded. As a matter of fact, in past years 

 "Blue Points" sold in retail stores actually were 

 taken from the Chesapeake Bay and North 

 Carolina. This is also true for "Cotuits" and 

 other popular brands. 



That the shape of oysters cannot be associated 

 with any particular geographical location is best 

 shown by the fact that all the kinds represented 

 in trade, including long and narrow "coon" 

 oysters which are regarded as being typical for 

 the tidal areas of the South Atlantic States, are 

 found in various bays and estuaries of Cape 

 Cod, Mass. The only shell character that 

 appears to be associated with the geographical 

 distribution of the species is the pigmentation 

 of the interior surfaces of the valves. In North 

 Atlantic oysters the inner surface is unpigmented 

 or very lightly pigmented (outside of the place 

 of attachment of the adductor muscle), while 

 in South Atlantic and Gulf oysters the dark 

 brown or reddish pigmentaton of the valves is 

 more pronounced. 



DIMENSIONS 



Oysters {C. virginica) of marketable size usually 

 measure from 10 to 15 cm. (4 to G inches) in height; 

 depending on the place of origin an oyster of this 

 size may be 3, 4, or 5 years old. 



As a rule, oysters do not stop growing after 

 reaching certain proportions but continue to 

 increase in all directions and, consequently, may 

 attain considerable size. Such old and very large 

 oysters are usually found on grounds undisturbed 

 by commercial fishing. The largest oyster in my 

 collection was found in the vicinity of Boothbay 

 Harbor, Maine. Its dimensions were as follows: 



20 



FISH AND WILDLIFE SERVICE 



