progress of the higher forms of life from the lower. The Brachiopods, the lowest of Mollusca, the Crinoids and Star-fish, the lowest of Echinodermata, and the Trilobites, among the lowest of Crustacea, abounded in the Paleozoic Age. The Crinoids and Brachiopods lived on through Secondary time, playing, however, an inferior role, and now have almost passed away, a few Brachiopods only and one Crinoid living at the present day. The Age of Mollusca, we have seen, was followed by an Age of Fishes, thus exhibiting a progress in the animal life of the globe. The fact of these fishes being Sharks and Ganoids is very significant: the important point to be noticed is, that whatever view be taken of the rank of the Ganoids among fish, they preceded the Teliosts and Batrachia, and that the Sharks with pavement teeth came before those with cutting teeth. The next two periods offer a further progress in the life of the globe, since we find the Batrachia (Frogs, Labyrinthodons) appearing in the Carboniferous, followed by the Reptiles (Proterosaurus) in the Permian, while the Insects are represented by the lower orders, of which the Neuroptera (May-flies) were very abundant in the Carboniferous. In the Secondary Age the Reptiles reach their climax, while the Bony Fishes, Mammals, and Birds are just appearing. The gradual unfolding of the vegetal kingdom during the Primary and Secondary Ages is as marked as that of the animal kingdom. An Age of Algae was followed by an Age of Acrogens; these gave way to Cycadae and Coniferae; the Cycadae, in their turn dying out, were replaced by the Palms of the Tertiary, associated with which are the Forest trees, among which the great Mammals lived, and the flowering plants offered then as now a resting-place for butterflies, which first appeared in this age.
Modern Geologists do not believe that life, since it first appeared, has ever been extinct all over the globe at the
