The mammals of Europe in Pliocene times were derived by very remote migrations from North America and, more directly, from southern Asia. The Oriental element is very strong, including types of rhinoceroses now peculiar to Sumatra and southern Asia, numerous mastodons very similar to the south Asiatic types of the times, gazelles and antelopes, including types related to the existing elands, and primitive types of horses and of tapirs. Among the carnivores in Europe similar to south Asiatic species were the hyænas, the dog bears (_Hyænarctos_), the civets, and the pandas (_Ailurus_); there were also the sabre-tooth tigers and numerous other felines. In the trees were found the south Asiatic and north African monkeys; and in the forests the axis deer, now restricted to Asia. But the most distinctive African-Asiatic animal of this period was found in the rivers; namely, the hippopotamus, which arrived in Italy in the early Pliocene and ranged south by way of the Sicilian land bridge into northern Africa and east along the southern shores of the Black Sea to the Siwalik hills of India. Thus, many of the ancestors of what we have termed the African-Asiatic mammal group of Pleistocene times had already found their way into Europe early in Pliocene times. In middle and late Pliocene times there arrived three very important types of mammals which played a great rôle in the early Pleistocene. These are: The true horses (_Equus stenonis_) of remote North American origin. The first true cattle (_Leptobos elatus_), originating in southern Asia. The true elephants, first _Elephas planifrons_ and later _E. meridionalis_, better known as the southern mammoth, both originating in Asia. The forests and river borders of the valley of the Arno, near Florence, contained all these African-Asiatic animals in Upper Pliocene times. Here they received their names which remind us of this region of Italy as it is to-day, such as the Etruscan rhinoceros (_Dicerorhinus etruscus_), the Florentine macaque (_Macacus florentinus_), Steno's horse (_Equus stenonis_), the Etruscan cattle (_Leptobos etruscus_), which was the earliest ox to reach Europe. In Italy and France these African-Asiatic mammals were mingled with ancestors of the more hardy Eurasiatic forest and meadow group. Of these the most graceful were a variety of deer with very elaborate or many-branched antlers, hence known as the 'polycladine' deer. In the forests roamed the wild boars of Auvergne (_Sus arvernensis_), also the bears of Auvergne (_Ursus arvernensis_), lynxes, foxes, and wildcats. In the rivers swam the otter and the beaver, closely allied to existing forms. Among the rocks of the high hills were the pikas or tailless hares (_Lagomys_), also hamsters, moles, and shrews.