THE GBIBBLE. 113 



deeper tunnels than the preceding creature, though it is not so 

 rapidly destructive, owing to the direction of its burrows, which 

 are driven straight into the wood, and do not cause it to flake 

 off so quickly as is the case when the Chelura excavates it. 

 Still, it works very great harm to the submerged timber, boring 

 to a depth of two inches, and nearly always tunneling in a 

 straight line, unless forced to deviate by a nail, a knot, or simi- 

 lar obstacle. The Grribble is a very tiny creature, hardly larger 

 than a grain of rice, and yet, by -dint of swarming numbers, it is 

 able to consume the wooden piles on which certain piers and jet- 

 ties are supported ; and in the short space of three years these 

 destructive Crustacea have been known to eat away a thick fir 

 plank, and to reduce it to a mere honey-comb. Sometimes these 

 two wood-boring shrimps attack the same piece of wood, and, in 

 such cases, the mischief which they perpetrate is almost incredi- 

 ble, considering their small dimensions and the nature of the sub- 

 stance into which they bore. The common fresh-water shrimp, 

 so plentifiil in our brooks Und rivulets, is closely allied to the 

 Grribble, and will convey a very good idea of its appearance. In 

 some parts of our coasts the ravages of these animals are so de- 

 structive, that the substitution of iron or stone for wood has be- 

 come a necessity. 



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