INTRODUCTION. 5 



Antiquarian Society,* that he could never understand how 

 " that broad flat surface inside each claw could be got rid 

 of without injury to the new claw ; however, by attentively 

 watching the process in several instances/'' he continues, 

 " I observed that in the act of drawing out the new claw, the 

 edge is cut through by these flat horny plates, the divided 

 parts immediately closing again, and speedily becoming so 

 adherent as to preclude their being re-opened." He has 

 also observed another fact, and it is this, that when " Crabs 

 cast off their claws and get new ones, the process can take 

 place only in the joint which is nearest the body ; if any 

 other be injured, they bleed to death; but if the nearest 

 joint be removed, there is little blood lost, and over the 

 wound a thin film forms, in the middle of which is a 

 tubercle. The common opinion among naturalists ap- 

 pears to be, that the new claw immediately begins to form, 

 and at the next casting of the shell it is perfected, though 

 it be small; but this is incorrect; when the old claw is 

 separated, the scar immediately forms, and remains till 

 the creature casts its shell. After the shell is cast, the 

 tubercle in the centre of the scar suddenly enlarges; and 

 under it may be discovered a small claw doubled on itself 



* Nov. 1855, reported in ' Zoologist,' p. 4972. 



