France there is a deposit of löss, he says, which has been derived from the washing of the ancient moraines. At the foot of the Alps, where black schists are largely developed, the löss is dark grey, but west of the secondary chain the same deposit is yellowish, and composed almost entirely of silicious materials, with only a very little carbonate of lime. This _limon_ or löss, however, is very generally modified towards the top by the chemical action of rain--the yellow löss acquiring a red colour. Sometimes it is crowded with calcareous concretions, but at other times it has been deprived of its calcareous element and converted into a kind of pulverulent silica or quartz. This, the true löss, is distinguished from another _lehm_, which Falsan recognises as the product of atmospheric action--formed, in fact, _in situ_, from the disintegration and decomposition of the subjacent rocks. Even this lehm has been modified by running water--dispersed or accumulated locally, as the case may be.[AR] [AR] Falsan: _La Période glaciaire_, p. 81. All that we know of the löss and its fossils compels us to include this accumulation as a product of the Pleistocene period. It is not of post-glacial age--even much of what one may call the "remodified löss" being of late Glacial or Pleistocene age. I cannot attempt to give here a summary of what has been learned within recent years as to the fauna of the löss. The researches of Nehring and Liebe have familiarised us with the fact that, at some particular stage in the Pleistocene period, a fauna like that of the alpine steppe-lands of western Asia was indigenous to middle Europe, and the recent investigations by Woldrich have increased our knowledge of this fauna. At what horizon, then, does this steppe-fauna make its appearance? At Thiede Dr. Nehring discovered in so-called löss three successive horizons, each characterised by a special fauna. The lowest of these faunas was decidedly arctic in type; above that came a steppe-fauna, which last was succeeded by a fauna comprising such forms as mammoth, woolly rhinoceros, _Bos_, _Cervus_, horse, hyæna, and lion. Now, if we compare this last fauna with the forms which have been obtained from true post-glacial deposits--those deposits, namely, which overlie the younger boulder-clays and flood-accumulations of the latest glacial epoch, we find little in common. The lion, the mammoth, and the rhinoceros are conspicuous by their absence from the post-glacial beds of Europe. In place of them we meet with a more or less arctic fauna, and a high-alpine and arctic flora, which as we all know eventually gave place to the flora and fauna with which Neolithic man was contemporaneous. As this is the case throughout north-western and central Europe, we seem justified in assigning the Thiede beds to the Pleistocene period, and to that interglacial stage which preceded and gradually merged into the last glacial epoch. That the steppe-fauna