The mammalian life of these 'full' Mousterian times, as found along the headwaters of the Danube, the Rhine, and the branches of the Dordogne and Vézère, is divided among the various faunal groups as follows: LIFE OF MIDDLE MOUSTERIAN TIMES TUNDRA LIFE. Woolly mammoth. Woolly rhinoceros. Scandinavian reindeer. Arctic fox. Arctic hare. Banded lemming. Arctic ptarmigan. ALPINE LIFE. Alpine marmot. Ibex. Alpine ptarmigan. STEPPE LIFE. Steppe horse. Steppe suslik. Moor-hen. ASIATIC LIFE. Cave-lion. Cave-hyæna. Cave-leopard. FOREST LIFE. Stag, lynx, wolf, fox, water-vole, brown bear, giant deer. Cave-bear. MEADOW LIFE. Bison. Wild cattle. It would appear that the reindeer, the woolly mammoth, and the woolly rhinoceros were already widely distributed over western Europe, accompanied by the arctic fox (_Canis lagopus_), the arctic hare (_Lepus variabilis_), and the banded lemming (_Myodes torquatus_). There is no proof that the musk-ox had at this time reached its extreme southerly distribution, and it would appear that the arrival of the second type of northern lemming from the region of the river Obi (_Myodes obensis_) did not occur until the close of Mousterian times,(21) because the great migration of these animals is recorded by their abundant remains in the so-called 'lower rodent layer' of all the stations along the Rhine and Danube, such as Sirgenstein, Wildscheuer, and Ofnet, after the final stage of Mousterian industry. In fact, this remarkable little rodent appears to mark the second maximum or close of the fourth glaciation by its migration all over western Europe, and wherever its remains are found in the grotto deposits they furnish one of the most important and positive of prehistoric dates, namely, that of the 'lower rodent layer.' The lemmings surpass all other mammals in the great distances covered by their migrations, and it would appear that this northern species swept all over western Europe at the same time, leaving its remains not only in the caverns along the Danube but in those of Belgium and of Thiede, near Braunschweig. The latter station, Thiede, was not far from the southern border of the Scandinavian glacier; it was subjected to a very severe arctic climate, as the only associates of the Obi lemming were the banded lemming, the arctic fox, the arctic hare, the reindeer, the mammoth, and the musk-ox. LIFE OF LATE MOUSTERIAN TIMES _Second Maximum of Fourth Glaciation_ Tundra, Steppe, Alpine, Asiatic and Meadow life, as above. Obi lemming. Musk-ox. Ermine. Arctic ptarmigan. Eversmann's weasel (Steppe weasel).