During the middle pleistocene, in the Thames valley, and at Clacton, the woolly rhinoceros, elephant, and mammoth competed for the same feeding-grounds with _Rhinoceros hemitœchus_, _R. megarhinus_, hippopotamus, and _Elephas antiquus_. Although all the characteristic pleiocene deer had retreated, the reindeer had not yet invaded that area: it was occupied by the stag, roe, the Irish elk, and Brown’s fallow deer. The whole assemblage of animals, the musk sheep being excepted, implies that the climate was less severe at this time, than when the reindeer spread over the same area in the late pleistocene age, and was far more numerous than the stag. It may, indeed, be objected that the classificatory value of the musk sheep is quite as great as that of _Rhinoceros megarhinus_; but in the case of the lower brick-earths, the evidence of the latter as to climate agrees with that of the whole assemblage of animals, while that of the former is altogether discordant. There are no caves either in Britain or on the continent which can be referred with certainty to this middle division. The machairodus, however, of Kent’s Hole, and of the cavern of Baume in the Jura (see p. 337), and the megarhine species of rhinoceros from the fissures of Oreston, probably inhabited those regions, while the temperate group of animals held possession of the valley of the Thames, and of that now sunk beneath the North Sea. _The Early Pleistocene Mammalia._ The fossil mammalia must now be examined, which inhabited Great Britain during the early pleistocene period, and before the maximum severity of glacial cold had as yet been reached. The fossil bones from the forest-bed, which underlies the boulder-clay on the shores of Norfolk and Suffolk, have for many years attracted the attention of naturalists and geologists. The magnificent collections of the Rev. John Gunn, and the late Rev. S. W. King, gave Dr. Falconer the means of proving that the fauna of the ancient submerged forest differed from that of any geological period which we have hitherto discussed: and the careful diagnosis of all the fossils from this horizon which I have been able to meet with, shows that it was of a very peculiar character, being closely allied to the pleiocene of the south of France and of Italy, and yet possessing species which are undoubtedly pleistocene. The following list is necessarily very imperfect, since the fragmentary nature of the fossils renders a specific identification very hazardous; and it only includes those which I have been able to identify with any degree of certainty.