Sea-anemones have been compared to garden asters, and indeed the resemblance is not slight. The living tentacles of the one might almost be taken for a rough copy of the thick petals of the other. In general form sea-anemones are round soft disc-like bodies, surrounded or trimmed by a border of fleshy tentacles, and mounted on a thick fleshy stalk or cylinder, which is usually either fastened to a rock or buried in the sand. They vary in size between half-an-inch and more than a foot in diameter. A splendid specimen, to be found in the Pacific, is fourteen inches across the disc. These creatures are not without a limited power of moving from place to place; though, in the case of most “attached” anemones, movement is extremely slow. A few kinds do not attach themselves at all, but rove freely through ocean-waters, after the fashion of their cousins the jelly-fishes. One particular species, which seems to approve of change of scene, and yet not to love exertion, has hit upon a clever dodge. When quite young it fixes itself upon the shell of a certain kind of crab; and as it grows larger, it gradually covers the whole back of the crab. Where the crab goes, the anemone goes; when the crab rests, the anemone rests. Oddly enough, the crab does not appear to object to his burden. This is no mere accidental comradeship, seen only in rare cases; for that special description of crab is never seen without its friend the anemone perched confidingly upon its back; and that special description of anemone is never seen without its friend the crab for a steed. A sea-anemone, like a coral-polyp, has a mouth and a stomach. But unlike the coral-polyp, it has the mouth and stomach for its own use, not merely in trust for the benefit of the whole community. When the pretty flower-like creature wishes to open itself out, it takes in a quantity of salt water. When it wishes to shut itself up, it spurts the water out, drawing its tentacles close. Both mouth and stomach are elastic; and it is able to swallow animals that are very little smaller than itself. Sometimes it gulps up greedily a whole crab or bivalve, digesting the soft animal parts, and getting rid of the useless shell as easily as it gets rid of water, when about to close. Soft and mild and helpless as a sea-anemone may seem, it is really far from being defenceless. Within that plump body, around the mouth, in the skin, about the tentacles, and along the slender hanging white cords, lie concealed thousands, even millions, of weapons. Each weapon is a very fine and delicate thread of hollow make, curled tightly up in a minute cell, ready for use. When a sea-anemone desires to injure or to kill, either in defence or in attack, it darts out a number of these little “lassos” as they are called.