It will probably have occurred to the intelligent reader that we have already had some insight into the Fossil world, when investigating the origin of Organic Rocks. We have seen, for instance, that Coal is the representative to our age of swamps and forests which once covered the earth with vegetation; that Mountain Limestone is in great part formed from the skeletons of reef-building corals; that the White Chalk of Europe is almost entirely derived from the remains of marine shells. But it should be observed that these and such like rocks, while they afford us much valuable information about the ancient organic condition of our planet, are not, strictly speaking, Fossil Remains. For, not only does the substance of the organic bodies they represent exhibit an altered character, but the internal structure has been in great part effaced, and even the outward forms and superficial markings have disappeared. They contain, it is true, great multitudes of Fossils. In the Coal, for example, are found, as we have seen, trunks of trees, together with the impressions of plants and leaves: in the Chalk and Mountain Limestone, fragments of shells and corals are often discovered in a state of perfect preservation. But the bulk of these formations is made up not so much of Fossil Remains, as of that into which Fossil Remains have been converted. Coal, for instance, is something more than Fossil wood; Chalk, and Limestone, and Marble, are something more than Fossil shells and corals.
Fossil Remains properly so called present a very much more lively picture of the ancient inhabitants of our Globe. But it is a picture that can but faintly be conveyed to the mind by the way of mere verbal description. He who would appreciate aright the reality and the significance of Fossil Remains must gather his impressions from actual observation. Let him go, for instance, to the British Museum, and walk slowly through the long suite of noble galleries which are there exclusively devoted to this branch of science. He will feel as if transported into another world, the reality of which he could scarcely have believed if he had not seen it with his own eyes. Before him, and behind him, and on each side of him, as he moves along, are spread out in long array forms of beasts, and birds, and fish, and amphibious animals, such as he has never seen before, nor dreamt of in his wildest dreams. Yet much as he may wonder at these strange figures, he never for a moment doubts that they were once indued with life, and moved over the surface of the earth, or disported in the waters of the deep. Nay more, though the forms are new to him, he will be at no loss, however inexperienced in Natural History, to find many analogies between the creation in the midst of which he stands, and the creation with which he has been hitherto familiar. There are quadrupeds, and bipeds, and reptiles. Some of the animals were manifestly designed to walk on dry land, some to swim in the sea, and some to fly in the air. Some are armed with claws like the lion or the tiger, others have the paddles of a turtle, and others again have the fins of a fish. Here is an enormous beast that might almost pass for an elephant, though an experienced eye will not fail to detect an important difference; and there is an amphibious monster that suggests the idea of a crocodile; and again a little further on is an unsightly creature which unites the general characteristics of the diminutive sloth with the colossal proportions of the largest rhinoceros.