SECTION V. Crabs, Lobsters, and other Marine Animals.

We now enter upon a description of a class of animal which naturalists call Crustacea, because they are crustaceous-that is, they have a crust, or hard covering; the term comes from the Latin crusta, which properly means a piece of ice. But all animals which have a hard coat, or covering, are not crustaceous, only those whose cases are divided into many portions, having numerous joints, which fitting loosely together, allow of a free movement in the inmates, or wearers, as they may be called; and of their growth to a certain extent. Those creatures which have shells composed of one, two, or more pieces, in which they live as in a kind of

house, are called testaceous, from the Latin testa, a shell; of these we shall have to speak presently. The covering of the crustacean is more like a suit of clothes, or armour, fitting not only to the body, but also to the limbs, as we see in the crab, the lobster, and the shrimp, as well as in the wood-louse, and several other small animals which are generaly called insects, and considered as such by those unacquainted with their peculiarities of structure.

These Crustacea were included by the great naturalist Linnæus in his apterous, or wingless order of insects; but later naturalists have altered this arrangement, and placed them by themselves in a class, which has many divisions. One grand distinction between insects and the marine crustacean, is that the former breathe through lungs, and the latter through gills, the difference of which has been already explained; their different modes of life render this necessary. There are, it is true, aquatic or water insects, but these carry down with them the air necessary to their existence, as a diver draws in a long breath, and so inflates his lungs, before he descends; the reservoir of the water spider is a little air bubble, like a diving bell. Another important difference which may be noticed in

the economy of the Crustacea, is that, long after it has attained what may be considered its perfect shape, it continues to increase in bulk; this the true insect never does, it undergoes great changes of form, and also of size; but when once it has attained its highest stage of development it grows no more, but, after a short season, dies. Not so the crab and the lobster; we see the members of one species of all sizes, and equally perfect in form, so that the largest might be taken for the smallest magnified. But how, it may be asked, about the clothes or armour of the crustacean? Does this grow with the body, and so always fit to a nicety? No; it gives or stretches to a certain extent, and then has to be got rid of, and this is the most curious point in the history of the animal.

Every year, at a certain season, the shelly or horny covering becomes soft, so that by the swelling of the parts enclosed, the seams open, and the animal is enabled, after some effort, to cast it off, as one would an old garment. Away it goes-head-piece and body-mail, boots and armlets, even the jaws and hard cuticle, or skin, in which the teeth are set-away it all goes, and the poor naked animal is weak and

defenceless, but not for long; before the old shell was cast off, preparations had been making for the new one; a membrane had begun to form over the whole of the parts which the shell covered, and this, when exposed to the air, rapidly thickened and hardened, and at the same time, by the pressure of the parts within, expanding so as to form a case much larger than the one rejected. Naturalists have calculated that the annual increase in size is about one-fifth. After a certain time the crustacean attains its full growth, and then there is no more reproduction of its covering, unless it should happen to lose a claw or other limb, in which case there is a fresh growth from the stump of the old one. Frequently this renewed portion does not become so large as that which it replaces, so that crustaceans are often seen with disproportionate members; these we must look upon as cripples, which have had their limbs torn off in desperate encounters with other tyrants of the deep, for these are mostly fierce and voracious creatures, or in struggles to escape from the net or line of the fisherman.

No one who has looked into the shallow tide pools, or the ditches of the salt marshes, or the holes and water-channels of the sand on the

shore, can have failed to notice the little sidling CRABS, some no bigger than a sixpence, that, if one attempts to catch them, scurry away at a prodigious rate, and hide under some friendly stone, or bunch of sea-weed. Cancer pagurus is the name given by naturalists to the common edible-that is, eatable-Crab of our shores; it is the most familiar example of the Cancer, or Crab family, which has many members, differing greatly in appearance and habits. This species sometimes attains a very large size, weighing several pounds; it is found chiefly in deep waters, at some distance from the shore, and is captured by sinking buckets, or nets, baited with putrid flesh or other animal matter; into the mouth of these it crawls, tempted by the odour of the bait, and is unable to extricate itself. The small edible Crab called Carcinus manas is the nimble little animal to which we have already alluded; it derives it first or generic name probably from the Latin for flesh, which is carnus. All the crabs are flesh-eating animals, and highly as they are prized as table delicacies, they are by no means nice in their feeding; they, as well as the lobsters and shrimps, are sometimes called Sea-scavengers. The French call this small species, which is as