CANCER PAGURUS. 377 
nerally placed at the end of pedicles- 
legs six, eight, or ten, besides two 
arms, terminating in cJielce, or claws. 
Lucy, These arms are, I suppose, 
what we call the large pinching claws r 
Mother, Yes ; in the cancer pagurus, 
or common crab, they are very powerful ; 
and it exerts them with such force and 
obstinacy, as to allow the arm to be some- 
times torn off rather than loose its hold. 
Crabs live many years, and annually 
change their shells ; previously to that 
operation they retire into the sand, and 
remain there till the new shell is hard 
enough to afford protection. In that 
soft state, however, they fall a prey to 
many other creatures, and numbers are 
destroyed by fishermen, who use them as 
bait. 
hucy. But how can fishermen find 
them, when hidden in the sand ? 
Mother, A considerable number usu- 
ally' retire together; and as they are weak 
and defenceless while soft, they place a 
hard-shelled crab as a sentinel. Though 
