This is the life of the period of the fourth glaciation, when a very cold and moist climate prevailed all over western Europe as far south as northern Spain and northern Italy. While the glacial fields were not so extensive as during the third or the second glaciation, the climate was very severe, as indicated by the southward migration not only of the arctic flora but of the mammals and birds of the tundra region bordering the southern shores of the Arctic Ocean. Two or three forms from the cold steppes of northern Russia also found their way into western Europe, but this was distinctly not a steppe period because of the prevailing moisture of the climate; in place of the westerly winds and great dust clouds of closing Acheulean times, cold mists and clouds heavy with moisture swept over the country, which during the winters was at times buried in snow, and subject to rapid changes of temperature. These climatic[AG] conditions appear to be demonstrated by the predominance of the arctic tundra life, mammals which were adapted only to severe weather and attracted by the northern flora. [Illustration: PL. V. The Neanderthal man of La Chapelle-aux-Saints, inhabiting the Dordogne region of central France in Mousterian times. Antiquity estimated as between 40,000 and 25,000 years. After the restoration modelled by J. H. McGregor. For the bodily proportions of this hunting race compare the frontispiece, Pl. I.] The summers were undoubtedly warm like the present Arctic summers, but very much longer in these southerly latitudes. It is not improbable that there were seasonal migrations, northward and southward, of the mammoths, rhinoceroses, and reindeer, and also that the northern flint quarries along the Somme and the Marne may have been visited chiefly during the warm summer season. The Asiatic mammals had entirely disappeared from the regions of France and Germany during the first maximum of the fourth glaciation, but there are some who maintain that during the amelioration of climate that followed, an interval in the Alpine region termed the _Laufenschwankung_ by Penck, the straight-tusked elephant and Merck's rhinoceros again migrated into northern France. It is true that occasionally we find the bones of these animals in close association with those of the woolly mammoth and the woolly rhinoceros. It is possible to explain such intermingling either as having occurred during the advance of the fourth glaciation, or as due to the northward and southward migration of the respective herds of mammals in the summer and winter seasons. As the period of the fourth glaciation continued it is certain that these Asiatic mammals entirely disappeared. At the same time the Neanderthals had passed through the first stage of development of the Mousterian industry and had reached what is known as the 'full' or 'high' Mousterian, which, with few exceptions, was carried on under the shelter of the overhanging cliffs or within the grottos.