6 HISTORY OF BIUTJSH CRUSTACEA. 



beneath the membrane of the scar ; this remains in a soft 

 state until the Crab again casts its shell, when the new 

 claw is set at liberty, is straightened out, and becomes hard 

 and calcareous like other parts of the body ; so that a claw, 

 instead of being renewed and perfected at once, or at the 

 first casting of the shell, is not so in reality until the shell 

 has been cast the second time." Were a similar process to 

 take place before the eyes of any one on a creature as bulky, 

 sav, as a buffalo, no flight of the imagination could conceive 

 of anything more marvellous ; and yet it is a common occur- 

 rence, one of the works of Him whose ways and name are 

 Wonderful. 



TVom the observations of the late Sir John Dalyell, pub- 

 lished in the Report of the British Association for 1851, 

 we may state that Crustacea begin to throw off their shells 

 even in the embryo state in which they first appear after 

 having left the e^g. After every change they assume more 

 and more of their perfect form. While the Crab is young, 

 and growing rapidly, frequent exuviations occur at brief in- 

 tervals, from three to five in the course of a year. Just 

 before the change the animal almost ceases to feed, and 

 becomes rather inactive ; when the process has commenced 

 it is effected in the course of a few hours, body and limbs 



