It is difficult to imagine forests of this modern character, which farther northward included a number of still more temperate and hardy species, as the setting of the great African and Asiatic life that roamed all over western Europe at this time. It was the presence of hippopotami, elephants, and rhinoceroses which gave to Lyell, Evans, and other early observers the impression that a tropical temperature and vegetation were characteristic of this long life period. These animals were formerly regarded as proofs of an almost tropical climate, but the more trustworthy evidence of the forests, strengthened by that of the presence of very numerous hardy types of forest and meadow animals, has set aside all the early theories as to extremely warm temperatures during Second Interglacial times. The remains of what is still conveniently known as the '_faune chaude_,' or warm fauna, are chiefly found in the sands and gravels of the ancient beds of the Neckar, Garonne, and Thames, and other rivers of the north and south, also in Essex, England. The most surprising fact is that the mammal life of western Europe remained entirely unchanged by the vast second glaciation just described; the few extinctions which occurred as well as a number of new arrivals may be attributed to new geographical connections with Africa on the south and to the steady progress of migration from the far east. [Illustration: FIG. 42. The hippopotamus (_H. major_) and the southern mammoth (_E. meridionalis trogontherii_), a pair of mammals which enjoyed a similar range over western Europe from the close of the Pliocene until the middle of Third Interglacial times, when their remains are found associated with flints of Pre-Chellean, Chellean, and early Acheulean age. One-sixtieth life size. Drawn by Erwin S. Christman.] There were four very important and distinctive new arrivals from the African-Asiatic world, namely, the straight-tusked or ancient elephant (_E. antiquus_), the broad-nosed rhinoceros (_D. merckii_), the African lion (_Felis leo_), and the African hyæna (_H. striata_), which bespeak close geographical connections with northern Africa. Of these the ancient elephant and the broad-nosed rhinoceros were close companions; they enjoyed the same regions and the same temperatures, their remains are very frequently found together, and they survived to the very end of the great life stage of western Europe, which closed with the advent of the fourth glaciation. They are in contrast to the other pair of great mammals which was already present in Europe in Pliocene and First Interglacial times, namely, the southern mammoth, at this stage known as _Elephas trogontherii_, which had a preference for the companionship of the hippopotamus (_H. major_); it would seem that these animals were less hardy because both disappeared from Europe a little earlier than the ancient elephant and Merck's rhinoceros.