It will be necessary to use a few scientific names, most of which are borrowed from the Greek and Latin languages, but I will explain the meaning of them all, so that they will be easily remembered. First of all, then, the pieces of the puzzle are called _fossils_, and the name comes from a Latin word meaning “dug out;” because they have been dug out of the ground either by man in making railways and mines, or by Nature in the many ways in which she works by cutting down cliffs and scooping out valleys. These fossils are bones of animals and fishes, the skins, shells, and wings of insects, and the stalks and leaves of plants, some of which have lain so very long in the ground that they have become as hard and heavy as stone. But the shape of them always remains, and the moment you look at them you see that they once belonged to living creatures. I shall give you pictures of some of these fossils; and no doubt you will be able to find some like them in the chalk and sands of the seaside—beautiful shells and bones of fishes. You may pick these out of the cliffs, and then go to the pools of salt water left among the rocks by the ebbing tide, and compare your fossils with the living shell-fish, and see how nearly those inhabitants of the ancient oceans resemble the creatures we find now, sporting in the water, just as these fossils did when the sand and chalk cliffs were under the sea. Of course all the bright colours are gone from the fossils, for the colour of animals fades away soon after they die, and the flesh does not last long; but the hard parts—the bones and shells—are not easily destroyed, because they are made of the same material as rocks. And when we look at the fossil plants we see the same thing. The colours of the green stems and leaves have quite faded, but the delicate shapes of the leaves and branches, and the grain of the wood, can still be seen, and you will have no doubt that they once lived and bore flowers and fruit, and died, as plants are living and dying every day.