M. Morlot has estimated with care the probable antiquity of three superimposed vegetable soils cut open at different depths in the delta of the Tiniere, each containing human bones or works of art, belonging successively to the Roman, bronze, and later stone periods. According to his estimate, an antiquity of 7000 years at least must be assigned to the oldest of these remains, though believed to be long posterior in date to the time when the mammoth and other extinct mammalia flourished together with Man in Europe. Such computations of past time must be regarded as tentative in the present state of our knowledge and much collateral evidence will be required to confirm them; yet the results appear to me already to afford a rough approximation to the truth. Between the newer or Recent division of the stone period and the older division, which has been called the Pleistocene, there was evidently a vast interval of time--a gap in the history of the past, into which many monuments of intermediate date will one day have to be intercalated. Of this kind are those caves in the south of France, in which M. Lartet has lately found bones of the reindeer, associated with works of art somewhat more advanced in style than those of St. Acheul or of Aurignac. In the valley of the Somme we have seen that peat exists of great thickness, containing in its upper layers Roman and Celtic memorials, the whole of which has been of slow growth, in basins or depressions conforming to the present contour and drainage levels of the country, and long posterior in date to older gravels, containing bones of the mammoth and a large number of flint implements of a very rude and antique type. Some of those gravels were accumulated in the channels of rivers which flowed at higher levels by 100 feet than the present streams, and before the valley had attained its present depth and form. No intermixture has been observed in those ancient river beds of any of the polished weapons, called "celts," or other relics of the more modern times, or of the second or Recent stone period, nor any interstratified peat; and the climate of those Pleistocene ages, when Man was a denizen of the north-west of France and of southern and central England, appears to have been much more severe in winter than it is now in the same region, though far less cold than in the glacial period which immediately preceded.