If we arrange the things we have been talking about in order, the oldest first, they would come thus: plumbago or black-lead—or, as I have called it, eodendron, “the life-dawn plant”—first, then hard coal, then soft coal, then lignite and jet, then bog oak and peat. But I must tell you something about bog oak and peat. In many of the swamps and bogs of the World the trunks of dead trees are found, which have become quite black and almost like lignite, because they have been buried so long. Thus, in the bogs of Ireland oak trees are often found, and they were most likely living when the reindeer inhabited Ireland. This old bogwood is made into beads for necklaces and other ornaments. Peat is a partly decayed vegetable substance, with beautiful little plants growing on its surface, and is really coal in its infancy. It is found all over the world more or less in wet places, and consists of the roots and stems of mosses and reeds, some of which are like the gigantic plants of the coal period, but very small in comparison. I have no doubt that in time some of these peat bogs may be turned into coal if they sink down and become covered with other earths, but at present they are all on the surface and so soft that they are dangerous to walk upon because one may sink in and be smothered. This, as far as we can trace it, is a sketch of the history of vegetable life on our Earth. We will go back to the coal for a moment and see what the animal life of that time was. The seas of the time of the coal forests were sometimes shallow, sometimes deep, and in the limestone rocks of the oceans which separated the great continents of that time there is a record of the inhabitants of the seas. The land plants were of more than 1,000 different kinds, and there were more than 200 kinds of fishes in the waters, and corals, shells, and small crab-like animals innumerable. The fishes were fellows with terrible teeth, and their bodies were covered with strong hard scales. One of these fish was thirty feet long, and there were others of considerable size. It is curious that the fishes of this time remind one of reptiles (lizards and crocodiles), just as the birds of a future time seem to have something of the reptile about them, as you will see by-and-by.