INTEODUCTIOX. 5 



their beaks, they ascend with them to a considerable 

 lieight, and then let them fall suddenly on some rough 

 or craggy place, by which means the shells are broken, 

 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, especially to 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- 

 posed to be implicated in similar offensive operations 

 among 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 

 animal, aud afterwards to have secured itself a retreat in 

 the empty shell. 



Shell-fish, however, are not only exposed to the vora- 



• Mr. INIawe states in his Travels in Brazil, that he saw a spot 

 of bare granite, not more than one hundred yards square, covered 

 with an immense number of mutilated shells ; the whole neigh- 

 bourhood was rich in wood and verdure, and the sea at least five 

 miles distant. On enquiry he was informed, that large flocks of 

 birds repaired every evening to this place with shells left by the 

 tide, which they let fall on the rod;, in order to obtain their con- 

 tents. 



