On any muddy stretch of beach, when the tide is out, you may see numbers and numbers of little twisted casts, just like those which you may find on the lawn in the garden on any warm damp morning. These are made by Lug Worms, or “logs,” as the fishermen generally call them, and they really consist of sand which the worm has swallowed during the last three or four hours. For lug worms burrow by swallowing mouthful after mouthful of sand, until they can swallow no more. They eat their way down into the sand, in fact, just as earth-worms eat their way down into the ground. And when their bodies are quite filled with sand, they come up to the entrances of their burrows and pour it out in the little twisty coils which everybody who has walked on the shore knows so well by sight. If you take a spade and dig down into the muddy sand you can find these worms in great numbers. They are just about as big as earth-worms, and are of all sorts of colours, some being brown, and some dark green, and some purple, and some crimson. But on each side of the body they always have thirteen pairs of bright scarlet tufts. These are the little gills by means of which they breathe, and if you put them under a microscope they look just like tiny bushes with brilliant red leaves. You would think, perhaps, that when a lug worm bores its way through the loose sand, the sides of its burrow would fall in behind it as fast as it passed along. But from the surface of its body it pours out a thin, sticky liquid which binds the sand together, and forms a kind of lining to the burrow, like the brickwork of a railway tunnel. The burrow is generally about two feet deep, and the worm always lives in it with its head downwards. The worm itself, when fully grown, is from six to ten inches long. PLATE XXXIV THE NEMERTES (1) This is quite one of the most curious creatures to be found on the sea-shore. It hides under large stones at the bottom of the pools, and looks rather like a tangled boot-lace. But it is really a kind of leech-like worm, and the wonderful thing about it is that it can stretch its body out to almost any length, just as if it were made of elastic. It always does this in catching its prey, which it seizes by means of its sucker-like mouth, which has a kind of beak inside it. Then it “plays” its victim just as an angler “plays” a fish, sometimes stretching its body out to a length of fifteen or twenty feet, then drawing it in again to a length of three or four, and so on over and over again, until its prisoner is quite exhausted, when it proceeds to devour it. PLATE XXXIV THE NEREIS (2)