by the written record. The appearance and disappearance of successive groups of wild animals, the varying climate and geography, the successive invasions of tribes, the gradual development of civilisation, fall within my scope. The materials necessary for this task are perplexing in their abundance, and lie scattered over a wide field; the progress of discovery is very swift, and there are great blanks in the story yet to be filled in. Nevertheless, after a preparation of many years by researches in this country and on the continent, it seems to me to be better to attempt to perform the task, however imperfectly, rather than to wait for that perfection which perhaps might never come.
The three Phases of Life on the Earth.
The history of life in Europe falls naturally into three great divisions, separated from each other by breaks of great magnitude. In the first or Primary, fishes and amphibians, and in the upper part a few reptiles, were the master beings which have left their traces buried in the rocks. The vegetation, now principally represented by the coal seams, consisted of pines, araucariæ, tree ferns, and gigantic trees (Sigillaria and Lepidodendron and Calamites), allied to the club mosses and marestails. In the second or Secondary, reptiles had the mastery, walking on the land as giant carnivores and herbivores (Iguanodons and Megalosauri), flying in the air as pterodactyles, or huge reptilian bats, swimming in the sea as great reptilian whales, seals, and walruses (Ichthyosauri, Pleiosauri, and Plesiosauri). The birds are represented by the Archæopteryx of Solenhofen, with a long tail Like that of a reptile, and in the Creta-
