THE CRAT-FISH. 191 



the greatest proficient in Chinese mechanical puzzles 

 may well be posed at this greater puzzle. One is 

 tempted to ask, too, remembering the beautiful arrange- 

 ment provided for the growth of the shell in the Sea 

 Urchin, why something similar was not devised to assist 

 the Crab ; why one creature should enjoy the protection 

 of its house of defence at so little trouble, the walls 

 gradually widening as his wants increase ; while an- 

 other has, every returning season, either to burst, or by 

 violent muscular efforts, to flay itself alive, and then 

 wait, defenceless and naked, till a new coat grows on its 

 back. I suppose happiness is equally distributed, and 

 that what would be death to one animal may be sport 

 to another ! Possibly the extraordinary efforts made 

 by the Crab or Lobster, in throwing off their shells, may 

 be attended with pleasurable sensations. 



The process of moulting has been observed by the 

 celebrated naturalist Reaumur in the fresh- water Cray- 

 fish (Astacus fluviatilis), and most probably that of other 

 kinds is effected in a similar manner. In the autumn 

 the Cray-fish retires into a hole, where it remains for 

 some time without food. While thus stationary, the 

 old shell becomes gradually loosened, and a new and 

 soft cuticle is formed beneath it. The Cray-fish is now 

 greatly excited, and by violent efforts seeks to free its 

 new skin from the old shell, which it is about to cast 

 away. When this has been done, the difficulty remains 

 of escaping from its trammels. Its limbs are so per- 

 fectly encased in armour, that, at first sight, it seems im- 

 possible to escape from the confinement without break- 

 ing the shell to pieces. But the Cray-fish has no such 



