THE BLACK-CLAWED CRAB. 343 



Sagacity Changing shells. 



though the hard-shelled crab, when he is on his 

 dut} r , advances boldly to meet the foe, and will 

 with difficulty quit the field, yet at other times 

 he shews great timidity, and is very expeditious 

 in effecting his escape ; if, however, he be often 

 interrupted, he will pretend death, like the spi- 

 der, and' watch an opportunity to sink himself 

 into the sand, keeping only his eyes above. In 

 the under part of the shell a crescent-formed 

 suture may be observed, which opens at the cast- 

 ing of the shell, and leaves a space sufficient for 

 drawing out the whole body; the thorax soon 

 after drops its breast-plate, and then the legs 

 quit their crustaceous coverings. The body is 

 now only enveloped in a soft skin, not unlike wet 

 parchment; and the animal is so helpless, as for 

 a while to be incapable of motion, but lies be- 

 tween the rocks till it has acquired sufficient 

 strength and hardness to bear the weight of its 

 body, and convey itself from place to place to 

 perform its usual functions. The old shell is left 

 in two divisions, one that covered the body, and 

 the other that inclosed the legs. Dr. Darwin 

 asserts that the stomach and intestines are also 

 cast with the skin, and that the first food the 

 animal takes after recovering its strength is the 

 old stomach. It sometimes happens that the 

 shell hardens prematurely, and fixes the animal 

 a prisoner in his crevice, for fishermen have 

 often found them thus immured. When crabs 

 are out of health they do not change their shells 



