CRUSTACEA. 217 



Mr. Warrington has observed it to take place every twelve 

 days in summer, in the common Prawn. Although the 

 moulting and increase of growth continues after the adult 

 state of the crustacean, yet it does not continue throughout 

 life ; and it is mentioned as a proof of this that Barnacles, 

 w^hose size proved them to be of several years' growth, have 

 been found on the thick and stony carapace of Lobsters and 

 Crabs, still living. 



"When the animal, becoming too large for its shell, is 

 about to moult, it leaves off feeding and retires to a safe 

 hole or corner, for security during the process. The crust 

 becomes loosened, the animal begins restlessly to rub its 

 limbs against each other, and twisting about the segments 

 of its body. Presently it will throw itself on its back, and 

 swell out its body so as to burst the membrane which unites 

 the carapace to the abdominal plates. Eaising the cara- 

 pace, it soon loosens it from its attachment. By slow and 

 apparently painful exertions, the legs, antennse, eyes, and 

 other members are disengaged, and the whole case is empty. 

 There are specimens of the common Lobster's cast shells 

 at the Zoological Society's Gardens, which are as perfect as 

 if the animal were still inhabiting them. 



