CONCHIFEKA OR BIVALVES. 



59 



is owing to the animal forming 

 its abode in wood which it meets 

 with in the sea, such as dead and 

 floating trees, piles, and even 

 ships : it is worm-shaped, and 

 about six inches long. In making 

 its excavations into the wood, 

 which it does by boring into the 

 substance in the direction of the 

 grain, each individual is careful 

 to avoid the tube formed by its 

 neighbour, and often a very thin 

 leaf alone of wood is left between ; it also, when 

 a knot occurs in its path, makes a turn to 

 avoid it. 



A great proof of the manner in which the 

 operations of this little animal may become 

 prejudicial to us was furnished some time ago 

 (1730) in Holland. In that country a consider- 

 able portion of the land and coast is below the 

 level of high water, and in order to prevent the 

 irruption of the sea, immense dikes have been 

 constructed along the shore, formed of large 

 masses of sand, and strengthened by large piles 

 driven into the ground : these piles were at- 



