Productive Power of Shell-Fish—Varieties of the Crustacean Family—Study of the Minor Shell-Fishes—Demand for Shell-Fish—Lobsters—A Lobster Store-Pond Described—Natural History of the Lobster and other Crustacea—March of the Land-Crabs—Prawns and Shrimps, how they are caught and cured—Scottish Pearl-Fisheries—Account of the Scottish Pearl-Fishery—A Mussel-Farm—How to grow Bait. Shell-fish is the popular name bestowed by unscientific persons on the crustacea and mollusca, and no other designation could so well cover the multitudinous variety of forms which are embraced in these extensive divisions of the animal kingdom. Fanciful disquisitions on shell-fish and on marine zoology have been intruded on the public of late till they have become somewhat tiresome; but as our knowledge of the natural history of all kinds of sea animals, and particularly of oysters, lobsters, crabs, etc., is decidedly on the increase, there is yet room for all that I have to say on the subject of these dainties; and there are still unexplored wonders of animal life in the fathomless sea that deserve the deepest study. The economic and productive phases of our shell-fish fisheries have never yet, in my opinion, been sufficiently discussed, and when I state that the power of multiplication possessed by all kinds of crustacea and mollusca is even greater, if that be possible, than that possessed by finned fishes, it will be obvious that there is much in their natural history that must prove interesting even to the most general reader. Each oyster, as we have seen, gives birth to almost incredible quantities of young. Lobsters also have an amazing fecundity, and yield an immense number of eggs—each female producing from twelve to twenty thousand in a season; and the crab is likewise most prolific. I lately purchased a crab weighing within an ounce of two pounds, and it contained a mass of minute eggs equal in size to a man’s hand; these were so minute that a very small portion of them, picked off with the point of a pin, when placed on a bit of glass, and counted by the aid of a powerful microscope, numbered over sixty, each appearing of the size of a red currant, and not at all unlike that fruit: so far as I could guess the eggs were not nearly ripe. I also examined about the same time a quantity of shrimp eggs; and it is curious that, while there are the cock and hen lobster, I never saw any difference in the sex of the shrimps: all that I handled, amounting to hundreds, were females, and all of them were laden with spawn, the eggs being so minute as to resemble grains of the finest sand.