182 BIVALVES. 



OSTREA Edulis. 



COMMON OYSTER. 



Specific Character. Shell more or less orbicu- 

 lar, inclining to oval, but subject to much vari- 

 ation in form and size, imbricated with scaly 

 laminae ; upper valve small and flattened, the 

 other convex ; inside pearly white, outside dull 

 brown. 



Oysters are generally found with their lower 

 valves fixed to rocks or loose stones, and fre- 

 quently to one another. Most of our rocky 

 coasts abound with these shells, but Essex and 

 Suffolk chiefly are celebrated for them. They 

 are dredged up by a kind of net, with an iron 

 scraper at the mouth, and are immediately 

 stowed in pits formed for the purpose in the 

 salt marshes, which are overflowed only at spring 

 tide, and from which sluices let the salt water 

 escape, retaining a depth of about eighteen feet. 

 The water being stagnant, in warm weather it 

 becomes green, and in a few days the oysters 

 acquire the same tinge ; they are then held in 

 great estimation in the market, but they do not 

 attain their greatest perfection under six or eight 

 weeks. 



Oysters are not considered fit for the table till 

 they are about a year and half old, and the fish- 

 ermen know their age by the increase in the size 

 of the distance which separate the circles of 

 laminae in the convex valve. When young 



