Exuviation of the Common Crab. 341 



21. Gymnogramma chrysophylla, ~\ 



22. Nephrodium molle, 



23. Adiantum cuneatum, J- natural size. 



24. Gymnogramma tartafea, 



25. Pteris serrulata. J 



III. — 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 exuviee 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 mora* 

 ing of August 1, it was found just then delivered from its covering. 



NO. iv. z 



