The life of the Pliocene is very modern in character. Little is known of the vegetation in North America, but in Europe it is marked by the continued disappearance of the characteristically tropical plants and by an approximation to the modern European flora. Many trees persisted, however, which are no longer native to that continent, but are still found in eastern Asia or in North America, such as Tulip Trees, Walnuts, Hickories, Magnolias, Sequoias, etc.

Plate XVII. - Tertiary Fossils from Florida.

Fig. 1, Marginella aurora, x 3/4, Miocene. 2, Nassa bidentata, x 3/4, Miocene and Pliocene. 3, Purpura conradi, x 2/3, Miocene. 4, Natica floridana, X 1/2, Miocene. 5, Mitra wilcoxi, x 1/2, Miocene. 6, Fasciolaria tulipa, x 1/2, Pliocene. 7, Typhis floridana, Pliocene. 8, Turbo rectogrammicus, x 1/2, Pliocene. (After Dall).

Marine Invertebrates are nearly identical with modern forms, and the great majority of Pliocene species of shells are still living.

The Mammals are still somewhat behind their modern successors, though much more advanced than their predecessors, Those of North America are still incompletely known, and the list is a short one. Mastodons, Horses, Rhinoceroses, Peccaries, and very large Llamas represent the hoofed animals, beside the Dogs, Cats, and Mustelines. The effects of the connection with South America are seen in the appearance of the gigantic Ground Sloths and Armadillos, and of southern families of Rodents. Jf this connection was actually established at the close of the Oligocene, it is difficult to see why the South American mammals should so long have delayed their migration to the north.

The early Pliocene mammals of southern Europe closely resemble those of modern Africa, - Wolves, Cats, Civets, Hyaenas, Monkeys, Rhinoceroses, three-toed Horses, Deer (of which Africa has none), a great variety of Antelopes and of Giraffe-like forms, and Swine. Mastodon and Dinotherium persisted, the latter attaining great size. India had a similar fauna, with certain geographical differences. Especially to be noted are the great variety of Oxen, the presence of Bears, true Elephants, and the Hippopotamus, of the first Old World Camels, and of the extraordinary Sivatherium and Brahmatherium, great four-horned creatures allied to the Giraffes. In the Upper Pliocene the true Elephants, Oxen, Hippopotamus, and Bears had extended their range to Europe, but not, so far as we know, to North America. In volcanic tuffs of probably Pliocene age on the island of Java was discovered a fossil, Pithecanthropus erectus, which nas attracted great interest and has been the subject of much discussion. According to one view, these bones, part of the skull and a thigh bone, represent one of the "missing links" in the ancestry of Man; according to another, they are human, but abnormal, while a third opinion regards them as belonging to a large ape.

The material is insufficient for a definite solution of the problem.

On the coast of Zululand, southeastern Africa, a small area of continental Upper Pliocene has yielded a few fossil mammals, which suffice to show that Africa had already acquired the fauna which characterizes it now. The list includes an elephant, rhinoceroses, hippopotamuses, and several antelopes.

The Climate of the Pliocene was, on the whole, evidently cooler than that of the Miocene, as is shown by the changes in the character of the vegetation and of the marine shells. On the American Atlantic coast this is not true, for here the Miocene waters were exceptionally cold and the Pliocene was warmer, but, on the other hand, the thin beds of Florida and the Carolinas represent but a small part of the Pliocene. In the English Pliocene the proportion of Arctic shells rises from 5 % in the oldest to over 60 % in the newest beds. The refrigeration was greater in the sea than on the land, for the vegetation shows that the air had not yet grown cold. That was to come later.