CANCER. ]47 



its* nakedness. The Cancer Bernhardus, feeling 

 its defenceless situation, and being in want of 

 a shell of its own, is obliged to put up with 

 any dead univalve it can meet with to its pur- 

 pose. From this circumstance it has obtained 

 the name of Hermit-crab, retiring within its 

 cell when at rest, but protruding the fore part 

 of its body when in motion, and in search of 

 its prey. 



The species of this numerous genus are not 

 entirely confined to the ocean ; some few are 

 found in lakes, and in rivers ; and there are also 

 terrestrial crabs, which live on the ground and 

 in the sand, where they dig holes which serve 

 them for a retreat. The Cancer Ruricola, or land- 

 crab, is a remarkable instance of the strong ef- 

 fect of instinct, which obliges them once a year 

 to leave their inland habitations, and seek the 

 sea-shore, for thepurpose of casting their spawn. 

 These crabs inhabit the tropical climates in 

 great abundance, and have their retreats in the 

 mountains. At the appointed time they descend 

 in immense bodies, and move towards the sea, 

 making a clattering with their claws, which 

 O 2 



