The habits of the principal crustacea are now pretty well understood, and their mode of growth is so peculiar as to render 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 are hatched, being so nearly ripe before 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 increase 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 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.