TEREDO. 13 



ful efforts of Government to extirpate it_, is still at its work 

 undermining British stabilities. In the little harbour of 

 Port Patrick it is now busy destroying the piles which sup- 

 port the pier. The tubes of this species, although seldom 

 seen in collections more than nine to twelve inches long, 

 are yet sometimes met with in the Irish piles as long as 

 two and a half feet. It is remarkable for the chambered 

 structure of its larger end, where the animal seems, after 

 completing its work, to have desired to come nearer the 

 opening, and for this purpose has removed a little at a 

 time, at each stage building behind it a wall to sustain the 

 body in its position. 



The gigantic shell named Se2:)faria by Lamarck, consist- 

 ing of a tube some six or seven feet long, belongs in all 

 probability to this genus. 



The boring or piercing of the wood is generally per- 

 formed in the direction of the grain, and proceeds pretty 

 evenly, until the borer becomes sensible of another tube 

 lying in his way, when he alters the direction of his work, 

 and thus carefully avoids invading his neighbour's territory. 

 Thus, in a piece of wood lying five or six years under water, 

 there may be hundreds of holes so close as to leave in some 

 places the thinnest possible space between them, and yet, 



