178 BIVALVES. 



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 shells 

 happen to be taken, they are always rejected and 

 cast back into the sea. Great Britain has for 

 many ages been noted for its oysters, which in 

 former times were sent as a peculiar delicacy to 

 the epicures of Rome. 



OSTREA Malleus* 



HAMMER OYSTER. 



Specific character. Shell flexuous, elongated 

 at the base, often produced into two lobes giving 

 it somewhat the form of a hammer, from whence 

 it derives its name; outside imbricated with 



* Plate IX. figure 8. 



