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 
* N-ov. 1855, reported in e Zoologist/ p. 4972. 
