1. The Cambrian epoch was probably inland and partly fresh water.
2. The Old Red Sandstone, the Carboniferous series (in great part), the Permian rocks and Trias (chiefly), were all formed in inland waters during one long continental epoch. This was by partial submergence brought to an end during the Liassic and Oolitic epochs, when the highlands of Britain formed parts of groups of islands along with other European palaeozoic rocks. At the same time true continental land was never far off ; for even in the deposits of the Inferior and Great Oolites in Lincolnshire and Yorkshire there is evidence of land and rivers, which land, growing in extent, at length formed by its drainage the great continental river of the Purbeck and Wealden series, as shown by the estuarine and freshwater deposits of England and other parts of Europe. The Dinosaaria of this continent had their allies in older deposits of Permian and Triassic age. The great geographical areas were the same.
3. A larger submergence closed this terrestrial epoch ; and in our northern European areas the sea attained great width and depth during the deposition of the Chalk, and all continental continuity of the old region was entirely broken up.
4. By subsequent elevation of the land above the sea, the fluvio- marine Eocene strata of Western Europe were formed, including in the term fluvio-marine freshwater beds of the whole series together with the London Clay and other formations, all of which were deposited not far from a river-mouth, or at least from shore. With this latter continent there came in a terrestrial fauna almost entirely new, and wonderfully different from that which preceded it. From that day to this, most of Europe has been essentially a continent, and its terrestrial fauna, in a large sense, of modern type.
If, according to ordinary methods (recognized if not absolutely true), we were to classify the known old terrestrial faunas (as distinguished from marine) of the greater part of North America, Europe, Asia, and probably of Africa, a palaeozoic epoch would extend from the Old-Red-Sandstone at least to Purbeck and Wealden times, and a Neozoic epoch at least from the beginning of the Eocene period down to the present day, the Upper Cretaceous times remaining unclassified ; while the marine epochs would be tolerably correctly, but provisionally, divided also into two, — one, palaeozoic, embracing the formations from Laurentian (or at least Silurian) to the close of the Permian times ; and all besides, down to the present day, would form one great Neozoic or later series. The terrestrial and the marine series at their edges overlap each other. In this sense, as regards marine strata, the terms Palaeozoic and Neozoic were first used by Professor Edward Forbes ; and the rejection of the three terms Palaeozoic, Mesozoic, and Cainozoic, as applied to terrestrial faunas, may be inferred from the remarks in Professor Huxley's paper on Dicynodon. The great life-gaps between the two terrestrial series may some day be filled up by the discovery of the traces of old continents containing fossilized modifications of forms that accompanied the lapse of time. The generic marine gradations
VOL. XXVII. PART I. T
