Chamaerops) and screw-pines (Pandanus, Nipa), together with early forms of fig (Ficus), elm (Ulmus), poplar (Populus), willow (Salix), hazel (Corylus), hornbeam (Carpinus), chestnut (Castanea), beech (Fagus), plane (Platanus), walnut (Juglans), liquidambar, magnolia, proteaceous plants (Fig. 193) resembling those of Australia and the Cape, water-bean (Nelumbium), water lily (Victoria), maple (Acer), gum-tree (Eucalyptus), cotoneaster, plum (Prunus), almond (Amygdalus), laurel (Laurus), cinnamon tree (Cinnamomum), and many more. The fauna likewise points to the extension of a warm climate over regions that are now entirely temperate. This FIG. 193.-Eocene Plant (Petrophiloides Richardsonii), natural size. is particularly noticeable with regard to the mollusca. The species are, with perhaps a few exceptions, all extinct, but many of the genera are still living in the warmer seas of the globe. Some of the most FIG. 194.-Eocene Molluscs. (a) Voluta luctatrix (3); (b) Oliva Branderi (natural size); (c) Cerithium tricarinatum (3). characteristic forms are species of Nautilus, Oliva, Voluta, Conus, Mitra, Cyrena, Cytherea, Chama. The genus of Foraminifera, called Nummulites from the resemblance of the organism to a piece of money, is enormously abundant in the limestones above referred to as nummulitic limestones. It must have flourished in vast profusion over the floor of the sea, which in older Tertiary time spread across the heart of the Old World from the Atlantic to the Pacific Oceans. Some of the most common fish-remains found in the Eocene strata belong to the genera Lamna, Otodus, Myliobates, Pristis. Reptilian life, which enjoyed such a preponderance during the Mesozoic ages, is conspicuously diminished in the Eocene deposits alike in number of individuals and variety of structure. The genera are chiefly turtles, tortoises, crocodiles, and sea-snakes, presenting in their general assemblage a decidedly modern aspect compared with the reptilian fauna of the Secondary rocks. Remains of birds are comparatively rare as fossils. We have seen that the earliest known type has been obtained in the Jurassic system, and that others have been found in the Cretaceous rocks. Still more modern forms occur in Eocene strata; they include one (Argillornis) which may have been a forerunner of the living albatross; another, of large size (Dasornis), akin to the gigantic extinct ostrich-like moa (Dinornis) of New Zealand; a third (Agnopterus) shows an affinity with the flamingo; while the buzzard, woodcock, quail, pelican, ibis, and African hornbill are represented by ancestral forms. That the early type which linked birds with reptiles was still living is shown by the remains of one curious genus (Odontopteryx) which had toothed jaws like those of the pterosaurs. But, as stated above, it was chiefly in higher forms of life that the FIG. 195.-Eocene Mammal (Palæotherium magnum, 37). fauna of early Tertiary time stood out in strong contrast with that of previous ages of geological history. The mammalia now took the leading place in the animal world, which they have retained ever since. Among the Eocene mammals reference may here be made to the numerous tapir-like creatures which then flourished (Coryphodon, Palæotherium, Fig. 195, Anchitherium, etc.) Some of the forms were intermediate in character between tapirs and horses, and included the supposed ancestors of the modern horse —small pony-like animals, with three, four, and even traces of five toes on each foot. Many of the mammals had decidedly marsupial FIG. 196.-Skull of Tinoceras ingens (about ). characters, though otherwise resembling wolves, foxes, wolverines, and other modern forms. There were likewise true opossums. Numerous herds of hog-like animals (Hyopotamus) and of hornless deer and antelopes (Dichobune, etc.) wandered over the land, while in the woodlands lived early ancestors of our present squirrels, hedgehogs, bats, and lemurs. Among these various tribes which recall existing genera, others of strange and longextinct types roamed along the borders of the great lakes in Western North America. The Tillodonts were a remarkable order, in which the characters of the ungulates, rodents, and carnivores were curiously combined. These animals, perhaps rather less in size than the living tapir, had skeletons resembling those of carnivores, but with large prominent incisor teeth like those of rodents, and with molar teeth possessing grinding crowns like those of ungulates. Still more extraordinary were the forms to which the name of Deinocerata has been given (Deinoceras, Tinoceras, Fig. 196). These were somewhat like elephants in size, and like rhinoceroses in general build, but the skull bore a pair of horn-like projections on the snout, another pair on the forehead, and one on each cheek. The Eocene rocks of England are confined to the south-eastern part of the country, from the coast of Hampshire into Norfolk. They vary in character from district to district, sands and gravels being replaced by clays according to the conditions in which the sediment was accumulated. They are prolonged into the north of France and Belgium. Arranged in tabular form, they may be grouped as follows: FRANCE AND BELGIUM. Marine gypsum and marls of Paris; Calcaire - grossier divided into (3) Sandstones and sands (Bruxellian) of Paniselian sands of Belgium. Sands of Bracheux (Paris basin), In striking contrast with these comparatively thin and locally developed deposits are those of the Alps, Southern Europe, and the basin of the Mediterranean. Masses of nummulitic limestone and sandstone, several thousand feet thick, have been upraised, folded, and fractured, and now form important parts of the great mountain chains which run through Europe and the north of Africa. Similar rocks have been uplifted along the flanks of the great chain of heights that sweeps through the heart of Asia, reaching in the Himalaya range a height of 16,500 feet above the sea-level. We thus learn not only that a large part of the existing continents lay under the sea during Eocene time, but that the principal mountain-chains of the Old World have been upheaved to their present altitudes since the beginning of the Tertiary periods. The great Eocene lake-basins of North America—so remarkable a feature in the geography—survived till a much later part of Tertiary time. OLIGOCENE. Under this name geologists have placed a group of strata usually of comparatively insignificant thickness, chiefly of freshwater and estuarine, but partly also of marine origin, which, in Western and Central Europe, show how the bays and shallow seas of that region in the Eocene period were gradually obliterated and replaced by land and by sheets of fresh water. They attain in Switzerland a thickness of several thousand feet of sandstones, conglomerates, and marls, almost entirely of lacustrine origin, and forming a group of massive mountains (Rigi, Rossberg). A large lake occupied their site and continued to be an important feature in the geography of Central Europe during this and the following geological period. Other sheets of fresh water were scattered over the west of Europe. One of the largest of these lay in Central France, over the old district known as the Limagne d'Auvergne. In Germany, lacustrine and terrestrial deposits, including numerous seams of lignite or brown coal, are separated by a group of strata full of marine shells, foraminifera, etc., showing how the lakes and woodlands were submerged beneath the sea. In the Paris basin, and in the Isle of Wight, the strata are chiefly of fresh-water origin, but contain occasional marine intercalations. Evidently the Oligocene period, throughout the European area, was one of considerable oscillation in the earth's crust. During this time, too, the volcanic eruptions took place whereby the great |