82 THE OYSTER. 



sary to throw a dredge overboard anywhere in the 

 oyster area, and to drag it along the bottom for a short 

 distance in order to bring it up full, is totally errone- 

 ous. Such a condition of things is quite within the 

 reach of the cultivator, but it never exists under natural 

 influences alone. In this country, as well as in Europe, 

 the oysters are restricted to particular spots called 

 " banks," or " beds/' or " rocks," which are as well 

 defined and almost as sharply limited as the tracts 

 of woodland in a farming country they are so well 

 marked that they may be laid down on a chart, or they 

 may be staked out with buoys; and even in the best 

 dredging grounds they occupy such an inconsiderable 

 part of the bottom that no one would have much 

 chance of finding oysters by promiscuous dredging, in 

 ignorance of their location. Although the young are 

 distributed every year by the tides and currents over 

 all parts of the bottom, the dredge seldom brings up 

 even a single oyster outside the limits of the beds, 

 under natural conditions. 



\f The restriction of the oysters to certain points does 

 not depend on the supply of food, for this is every- 

 where abundant, nor to any great degree upon the 

 character of the water. It is almost entirely due to the 

 nature of the bottom. 



The full-grown oyster is able to live and flourish in 

 soft mud so long as it is not buried too deeply for the 

 open edge of the shell to reach above the mud and 

 draw a constant supply of water to its gills; but the 

 oyster embryo would be ingulfed and smothered at 



