< JIAP. ix. J NATUKAL HISTORY OF THE CRUSTACEA. 391 



der a close inspection of their habits a most interesting study. 

 As has been stated, a good-sized lobster will yield about 

 20,000 eggs, and these re hatched, being so nearly ripe be- 

 fore they are abandoned by the mother, with great rapidity 

 it is said in forty-eight hours and grow quickly, although the 

 young lobster passes through many changes before it is fit to 

 be presented at table. During the early periods of growth it 

 casts its shell frequently. This wonderful provision for an in- 

 crease of size in the lobster has been minutely studied during 

 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 off 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 difficult to believe that the great 

 soft animal ever inhabited the cast-off habitation which is 

 lying beside it, because the lobster looks, and really 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 unneces- 

 sary ; 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 



