The next thing picked up was a piece of cork, covered with barnacles. Barnacles are small shell-fish, growing on long leathery stems, by which they fasten themselves to floating wood, or the bottoms of vessels. They are not so mischievous as the worms mentioned before, as they do not actually eat the wood; but when, as is sometimes the case, they thickly cover the bottom of a ship, they prevent it from going quickly through the water. It is sometimes found necessary to take a ship into a dock, in order to scrape off the barnacles. A piece of stone picked up by Henry, looking like a coal-cinder, but white, Mr. Miller said was pumice-stone. It is one of the kinds of stone thrown up by volcanoes, or burning mountains. It is so light that it floats on water. He thought that this piece might, perhaps, have been thrown from a burning mountain into the sea, or that it might have been thrown overboard from a ship. It is used on board ships to scrub the decks with, and on land painters use it in scraping off paint from wood which is to be coated afresh. “On the whole,” said he, “most probably it came direct from a volcano, for I scarcely ever came to this part of the coast without finding some, and it could scarcely happen that pumice-stone would always be falling overboard by accident.” [Illustration: WHELK.] [Illustration: DONAX.] [Illustration: VENUS CHIONE.] The number of shells which lay scattered along the beach was very great. Some were like snail-shells, but more solid. Mr. Miller knew the names, but as he thought that Henry would not be able to recollect them, he only told him that they crawled about rocks and sea-weeds, very much as snails do on land, some living on sea-weed, and others on dead fish, or any animal substance they can find. Those which are named periwinkles and whelks are gathered by people who live near the sea, and sold for food, but they are neither nice nor wholesome. Others were what Mr. Miller called bivalves; that is, each animal had two shells, fastened together by a hinge. There were a great many large white cockle-shells, deeply furrowed, and having rows of sharp points on the outside. Some were yet larger, brown outside and white within, and strong enough to scoop up sand with; others, which were flatter, were scarcely thicker than paper. Most of these were single, and had no fish in them; but many smaller kinds were found which had been washed in without injury. These were stowed away very carefully. The most singular of all was a white one, four or five inches long, shaped something like the pod of a pea, but open at both ends. This Mr. Miller called a razor-shell, and said that the animal lived in the sand, burrowing in it like an earth-worm, and, perhaps, living on the small sea-insects which it finds. [Illustration: RAZOR-SHELL.]