238 HALF AN, HOUR WITH CRUSTACEA. 



common edible crab of our fishmarkets. It was 

 evidently known to the ancient Komans by the 

 name of Carabus hence the common name, given 

 to the whole of the short-tailed crustaceans, of 

 " Crabs." It abounds off rocky coasts, and smaller 

 individuals are also seen burrowing in the sands, 

 where they will endeavour to evade notice by flat- 

 tening themselves, and trying to pass for pebbles 

 another instance of the great law of mimicry which 

 we find adopted so generally in the animal kingdom. 

 The crabs live on all kinds of animal garbage, and 

 so far are the scavengers of the deep. As is 

 generally known, both crabs and lobsters go through 

 a series of moultings, or casting off of the shell, 

 before the final and full-grown stage is arrived at. 

 The shell has not the power of being enlarged, like 

 that of the sea-urchins, and so no other resource is 

 left but to throw it off altogether, in order that a 

 new one may form which shall better fit the in- 

 creasing bulk of the animal parts. At certain times 

 of the year, this moulting takes place. The Eev. 

 J. Gr. Wood gives the following as shed by the 

 lobster, in addition to the external coat : 



" The footstalks of the eyes, 

 The external cornea of the eyesj* 

 The internal thoracic bones, 

 The membrane of the ear, 

 The membranous covering of the lungs, 

 The tendons of the claws, 

 The lining of the stomach, and 

 The stomachic teeth." 



