We ran on into the study, where we found the Elf feeling under the bookcases and tables, looking everywhere for the lost guests. We never saw the others again. But we took the one the Imp had caught back to the pond, and, as we put it in, made a vow not to keep newts again. They are the most escapable things we have ever tried to keep. Besides, they look jollier in the pond, and are probably very much happier. As the Elf said, "We should try to think how we should like it if other things collected us." It certainly would not be pleasant to be bottled up in muddy water for the little newts to see. It is far best to leave them alone, and, when we want to see them, to come quietly over the common to the edge of the pond, when we may easily see half-a-dozen water-dragons run out from the soft mud, and swim, with quick, hasty flaps of their tails, and jerky paddlings of their arms and legs, out into the depths of the pool. When we lean out over the pond and take a handful or a netful of the duckweed, and pull it to pieces on the bank, we find some of the most daintily-shaped snails fastened among the mass of tiny pale stems. The Imp and the Elf always think that they are like very wee snakes, coiled round on themselves in little flat coils. And really they are just the same shape as those stone snails that were once alive, that grown-up people call ammonites. There is a fairy story about those stone snails that shows how other people beside the Imp and the Elf have thought them like serpents. Up in the north country there was an abbey by the sea, and in the abbey a saint lived called Hilda. And all the countryside was made dangerous for foot passengers by crowds of poisonous snakes. The folk of the country asked the saint to help them; for they could not walk abroad without fear of being bitten. They could not let their children out alone, because of the deadly things. So the saint summoned all the serpents to the abbey and, standing on the abbey steps, she turned them into stone, and as they stiffened they coiled up in flat circles like the little snails we find among the duckweed stems. That is the story, but we know now that these stones that they find are really snails that lived thousands of years ago, and have gradually been changed into stone. The duckweed snails are fine things for keeping water clear and pure, and the Imp and the Elf always have a few of them in their aquarium to prevent the water from growing green and stagnant and unhealthy. But you shall hear all about that in the last chapter of the book.