Dr. Kobelt quite agrees with me in thinking that the remains of the mollusca found along with the so-called "steppe-mammals" afford no proof of a steppe-character of the country at the time when they were alive (p. 166). Nor do the mollusca which have been found in England in the Forest-Bed and the succeeding pleistocene strata support such a view. The Forest-Bed, generally regarded as belonging to the Upper Pliocene, I believe to be an inter-glacial pleistocene deposit--contemporaneous with the loess formation in Germany. Of fifty-nine species of land and freshwater mollusca which have been discovered in this bed, forty-eight species, according to Mr. Clement Reid (p. 186), are at present living in Norfolk, six are extinct, two are continental forms living in the same latitudes as Norfolk, and the other three are all southern forms. Not a single species has a particularly northern range. Of the land and freshwater mollusca of the South of England in the succeeding pleistocene deposits, six species are now no longer living in the British Islands, but only one (_Helix ruderata_) can be looked upon as an Arctic or Alpine form. After this short digression on the mollusca, I will briefly recapitulate what is known about the early history of the Siberian mammals, which will assist us in tracing the cause of their migration to Europe. We have in Siberia problems quite as difficult of solution as the European ones. Volumes have been written to explain the former presence of Arctic mammals like the Reindeer in Southern Europe, and the most extraordinary demands on the credulity of the public have been made by some geologists in their attempts to account for this comparatively simple problem. In Northern Asia a somewhat similar phenomenon, but much more difficult of explanation, has taken place. Mammals have been found fossil in recent geological deposits in localities where they do not now occur, and apparently the Siberian and the European deposits are of about the same age. Now, however, comes the extraordinary difference. In Europe the Arctic mammals went southward, but in Siberia the Southern ones went northward. Not only do we find the Saiga-Antelope, Tiger, Wild Horse, European Bison, Mammoth, and Rhinoceros in the extreme north of the mainland of Siberia; their remains have even been obtained in the New Siberian Islands. As these islands are situated in the same latitude as the northern part of Novaya Zemlya,--indeed, not far south of the latitude of Spitsbergen,--the fact of such huge mammals having been able to find subsistence there at apparently quite a recent geological period seems an astounding fact. It may be urged that their bones might have been carried so far north by ice, or by some other equally powerful agency. But Tcherski and all other palæontologists who have examined these northern deposits are unanimous in the belief that these herbivores and carnivores lived and died where their remains are now found.