ables it to grip the columella, or upper part of the inside of the shell that it occupies, thus keeping itself snugly in place. As the crab increases in size by growth, it has to change its home for one more roomy; and this leads to some remarkable exhibitions of its instincts. The sight, which we have often beheld, is one of exciting interest. Watch, now, if you please. Here is a fat little hermit-crab, whose domicile, like a strait-jacket, has become decidedly uncomfortable, and he is somewhat distracted about it. He is out a house-hunting—that is a literal fact. See, he has found an empty shell. It is not so handsome as the one he now occupies, but it is a little larger. Look, how he almost lifts it up among his ten feet, every one of which is an interested inspector, as each must bear its part in sustaining the establishment. Now he rolls it round and round, all over and over, delicately manipulating its sculpture occasionally; he is not only testing its specific gravity like a philosopher, but also seems to have an eye to appearances. Now comes the most essential, the inspection of the interior. Will it fit? That is the chief consideration. He inserts his longest finger, and thoroughly probes the whole matter. One more trial—and now it seems that the antennæ, or feelers, enter into the consultation. And what an amount of feeling deliberation does this step involve! Well, the thing appears to be satisfactory. It is evidently decided that the new house will answer. And now comes the most trying time of all—for "moving" is a trying time. But Pagurus is actuated by considerations that fall not to the lot of migratory mortals of the bipedal sort. His accountability is of the ten-talent order. With his eyes he surveys the entire situation. What! Yes, it is so! He has moved, and settled, and has got the house "all to-rights." The whole thing was done in the twinkling of an eye. It vacates the old house, whisks its tail round, and enters the new one backward, as if shot into it from a gun. In fact, unless watching intently, the whole movement will elude the eye, like a trick of legerdemain. And the cause is not far to seek. If that soft, nude, defenceless body were exposed but for an instant, it might become the prey of some darting fish.
These hermit-crabs are highly pugnacious. We once took a pair of them that we suspected of being anxious to change their houses. They were put in a vessel of sea-water, and, full in sight of them, was placed an empty winkle-shell, which we supposed was of the right size. How they did fight for it! It was a battle for life. One succumbed, at last, and died. The survivor coolly surveyed his victim, and then surveyed the new premises. After this, he promptly entered into possession; and then, pitiful to relate, he fell-to eating his defunct comrade. Oh, the cannibal!
The cut (Fig. 4) given of a hermit-crab shows actinea, or zoöphite, upon the shell. These are sometimes called sea-anemones, and animal flowers, on account of their being real animals, with a flower-like form.
The class Crustacea, which embraces the creatures of whom we
