Exuviation of the Common Crab. 341 
21. Gymnogramma chrysophylla, ^ 
22. Nephrodium molle, 
23. Adiantum cuneatum, [-natural size. 
24. Gymnogramma tartarea, 
25. Pteris serrulata, J 
111. Observations on the process of Exuviation in the Common 
Crab {Cancer pagurus, Linn.) By JONATHAN COUCH, F. L. S. 
IN a former paper, inserted in the Magazine of Zoology and Bo- 
tany for August, (p. 170,) it is shewn that the manner in which the 
lobster disengages itself from its shell is different from that of the 
prawn and river crayfish. I will now proceed to describe so much 
as I have been able to observe, of the manner in which the same 
natural process is effected in the common crab, Cancer pagurus, 
Linn, and Leach ; and which will be found to differ from what has been 
witnessed in any of the (Brachiouri) long-tailed species, thus ren- 
dering it probable that great diversity may exist in the remaining 
families of the great order of Crustaceans ; in none of which have 
any of the particulars been hitherto observed. 
It is necessary, however, to premise, that I do not know how much 
of novelty my account may be found to possess ; the only work on 
the subject that is within my reach being Dr M. Edwards's recent 
and hitherto unfinished History of the Crustaceans, already referred 
to. This author makes a slight reference to some papers by Mr 
Collinson, in the Philosophical Transactions, on the exuviation of 
the common crab ; but, being unprovided with these works, I can 
only conclude concerning them, that they do not contain anything 
to supersede my remarks, since otherwise this learned naturalist 
would not have failed to have extracted their substance ; and I am 
confirmed in this opinion by the fact, that in some late works on 
physiology, of deservedly high reputation, what is given on this sub- 
ject is meagre and inaccurate. 
When about to throw off its exuviae the crab commonly retires to 
some secret place, in the near neighbourhood of rocks that will af- 
ford it shelter when unable to escape from danger, or defend itself 
from enemies. Its craving appetite seems also at this time to be 
suspended ; but the particular subject of my observation differed 
from others, in wandering into a crab-pot at this period, in search of 
food ; and being known by the fishermen to be what is called peel } 
that is, about to throw off its crust, it was transferred to the safe 
custody of the store-pot, on Saturday, July 30th, where, on the morn- 
ing of August 1, it was found just then delivered from its covering. 
NO. iv. z 
