94 HOMKS WITHOUT HANDS. 



Although very small, it is terribly destructive, and does no 

 small damage to wooden piles driven into the bed of the sea. It is 

 furnished with a peculiar rasping instrument, by means of which 

 it is enabled to scrape away the wood and form a little bnn-ow, 

 in which it resides, and which supplies it with nourishment as 

 well as with a residence. The tunnels which it makes are mostly 

 driven in an oblique direction ; so that when a large number of 

 these creatures have been at work upon a piece of timber, the 

 effect of their united labours is to loosen a flake of variable 

 dimensions. As long as the weather is calm, the loosened flake 

 keeps its position ; but no sooner does a tempest arise, than the 

 flake is washed away, and a new surface is exposed to the action 

 of the Chelura. 



When the Cheltira is placed on dry land, it is able to leap 

 nearly as well as the sand-hopper, and performs the feat in a 

 similar manner. 



This is not the only wood-boring crustacean with which our 

 coasts are pestered ; for the Gkibble (Limnoria terebrans) makes 

 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 tunnelling in a straight 

 line, unless forced to deviate by a nail, a knot, ot similar obstacle. 

 The Gribble 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 jetties 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 honeycomb. Sometimes these two wood-boring shrimps 

 attack the same piece of wood, and, in such cases, the mischief 

 which they perpetrate is almost incredible, considering their 

 small dimensions and the nature of the substance into which 

 they bore. The common fresh-water shrimp, so plentiful in our 

 brooks and rivulets, is closely allied to the Gribble, and will 

 convey a very good idea of its appearance. In some parts of our 

 coasts the ravages of these animals are so destructive, that the 

 substitution of iron or stone for wood has become a necessity. 



