It is this seasonal alternation, as well as the recurrence, either seasonal or secular, of milder climate, which explains the survival or return of the Asiatic fauna even after the close of the Acheulean industry and when the Mousterian industry was well advanced. From deposits found at Grimaldi, in the _Grotte des Enfants_ and in the _Grotte du Prince_, it has long been said that men of early Mousterian times lived contemporary with the hippopotamus, the straight-tusked elephant, and Merck's rhinoceros in the genial climate of the Mediterranean Riviera. More recently the same animals have been found as far north as the Somme valley in the 'river-drifts' of Montières-les-Amiens.(1) Here, again, we find remains of the hippopotamus, the straight-tusked elephant, and its companion, Merck's rhinoceros, in Mousterian deposits, a surprising discovery, because it had always been supposed that a cold climatic period had set in all over western Europe even before the close of the Acheulean culture. But there is also evidence of a temperate climate still prevailing in the Thames valley in the period of the Mousterian 'floors.'(2) Again, along the Vézère valley, Dordogne, we find that at the station of La Micoque, where the industry marks the transition between late Acheulean and early Mousterian times, Merck's rhinoceros is found in the lowest layers associated with remains of the moose (_Alces_). There is evidence that Merck's rhinoceros and the straight-tusked elephant lingered in western Europe during the whole period of the early development of the Mousterian industry. As observed above, these animals were hardier than the southern mammoth, which was the first of the Asiatic mammals to disappear, soon to be followed by its companion, the hippopotamus. Even after the advent of the closely associated tundra pair, the woolly mammoth and the woolly rhinoceros, Merck's rhinoceros persists, as, for example, in the deposits of Rixdorf, near Berlin, where this ancient type occurs in the same deposits with the woolly mammoth, the woolly rhinoceros, the reindeer, and the musk-ox, as well as with the forest forms, the moose, stag, wolf, and forest horse. The extreme northern latitude of this deposit explains the absence of the straight-tusked elephant, which may at the time have been living farther to the south. The same mingling of south and north Asiatic mammals is found at Steinheim, in the valley of the Murr, some degrees to the west and south of Rixdorf, not far from Göttingen, where we find Merck's rhinoceros(3) and the straight-tusked elephant in association with the woolly mammoth, the woolly rhinoceros, the giant deer, and the reindeer.