272 NATURAL HISTORY OF THE CRUSTACEA. 



its period of moulting. Mr. Jonathan Couch says the additional 

 size which is gained at each period of exuviation is perfectly- 

 surprising, and it is wonderful to see the complete covering of 

 the animal cast oflF like a suit of old clothes, while it hides, 

 naked and soft, in a convenient hole, awaiting the growth of 

 its new crust. In fact, it is diflScult to believe that the great 

 soft animal ever inhabited the cast-oflf habitation which is lying 

 beside it, because the lobster looks, and reaUy is, so much 

 larger. The lobster, crab, etc., change their shells about every 

 six weeks during the first year of their age, every two months 

 during the second year, and then the changing of the shell 

 becomes less frequent, being reduced to four times a year. It 

 is supposed that this animal becomes reproductive at the age of 

 five years. In France the lobster-fishery is to some extent 

 " regulated." A close-time exists, and size is the one element 

 of capture that is most studied. All the small lobsters are 

 thrown back to the water. There is no difficulty in observing 

 the process of exuviation. A friend of mine had a crab which 

 moulted in a small crystal basin. I presume that at some 

 period in the life of the crab or lobster growth will cease, and 

 the annual moulting become unnecessary ; at any rate, I have 

 seen crabs and other crustaceans taken from an island in the 

 Firth of Forth which were covered with parasites evidently 

 two or three years old. 



To describe minutely the exuviation of a lobster, crab, or 

 shrimp, would in itself* form an interesting chapter of this work, 

 and it is only of late years that many points of the process 

 have been witnessed and for the first time described.- Not long 

 ago, for instance, it was doubtful whether or not the hermit- 

 crabs (Anomoura) shed their skin ; and, that fact being settled, 

 it became a question whether they shed the skin of their tail ! 

 There was a considerable amount of controversy on this delicate 

 point, tUl the " strange and unexpected discovery " was made 

 by Mr. Harper. That gentleman was fortunate enough to 

 catch a hermit-crab in the very act, and was able to secure the 

 caudal appendage which had just been thro-wn oS. Other 

 matters of controversy have been instituted in reference to the 

 gro-vrth of various members of the Crustacea; indeed, the young 

 of the crab in an early stage have before now been described 

 by naturalists as distinct species, so great is the metamorphosis 

 they undergo before they assume their final shape — ^just as the 

 sprat in good time changes in all probability to the herring. 



