INTRODUCTION. xvii 



mit of being penetrated by their beaks or talons, they as- 

 cend with them in their beaks to a considerable height, 

 and then let them fall suddenly on some rough or craggy 

 place, which breaks the shells, and the fish becomes an 

 easy victim. 



Crabs and other crustaceous animals, are known to 

 make serious attacks on the testaceous orders. The lar- 

 ger sort of crabs are able by their great strength to open 

 the valves of most shells by main force; but those of 

 smaller dimensions make their inroads in a different man- 

 ner: the Pea-crab, in particular, is very destructive to 

 Bivalves, and especially muscles; it enters their shells 

 whenever it has the opportunity of finding them open, 

 and there remains preying upon the fish, till it has en- 

 tirely consumed it; at which period the shell opens, the 

 crab takes his departure, and proceeds to make similar 

 depredations elsewhere. 



Another species, called the Hermit-crab, is also sup-r 

 posed to be implicated in similar offensive operations a- 

 mong Univalves, for it is frequently found housed in the 

 vacant habitation of some Buccinum or Whelk, and is 

 therefore suspected of having previously devoured the a- 

 nimal, and afterwards to have secured itself a retreat in 

 the empty shell. 



Shellfish, however, are not only exposed to the vora- 

 city of other animals, but they frequently are assailed by, 

 and fall victims to each other. The Serpulae, Pholades, 

 and Anomiae, are celebrated for affixing themselves to, and 

 perforating other shells, in which they bore a small cir- 

 cular hole or aperture, that affords them access to the ani- 

 mal, which they feed upon and finally destroy. 



Shell-fish, though they are the universal prey of ani- 

 mals, birds, and fish, yet, in their turn, have some op- 

 c 



