202 OYSTERS, AND ALL ABOUT THEM. 



extended, of strata, more or less thick and horizontal, in 

 which the shells are still in the position they originally 

 occupied, and almost without any admixture of foreign 

 bodies. Even the bivalves, which live vertically sunk in 

 sand or mud, must also form sorts of strata, because the 

 individuals newly born are deposited by the parents above 

 themselves, so that, sinking in the mud in proportion as 

 they enlarge in bulk, they depress their parents and the 

 oysters below them in succession, so as to remove them 

 sufficiently from the surface of the soil, to prevent their 

 receiving any water, the consequence of which is death. 

 Then their shells, vertical while the animal was living, 

 begin to incline by degrees, become horizontal, are filled 

 with the substance in which they are sunk, resist the pres- 

 sure of the accumulated strata, so as sometimes to remain 

 perfectly entire, or, if not so, they are broken and crushed, 

 and disposed in beds more or less free from every other 

 shell, or even from any other foreign body, (z') 



The sea-board of Georgia, one of the most southern of 

 the United States of North America, cannot fail to arrest the 

 attention of the observant traveller, and excite his admira- 

 tion of what may be truly termed a natural phenomena on 

 extensive scale, in the formation of its oyster-banks. 



The land from the sea, for about the space of from 

 twelve to eighteen miles, is completely alluvial, and in 

 general consists of uncultivated marsh lands, through 

 which an iron rod might be thrust to the distance of 

 eighteen or twenty feet. A great number of large creeks 

 and rivers are found meandering through these marshes, 

 and, owing to the sinuosities, invariably resulting from 

 running water, the bends of these rivers would, in a short 



(/) " Adventures of an Oyster," pp. 64-5. 



