Man, _Homo_. Lion, _Felis leo spelæa_. Wild Cat, _F. catus_. Spotted Hyæna, _Hyæna crocuta var. spelæa_. Grizzly Bear, _Ursus ferox_. Brown Bear, _U. arctos_. Wolf, _Canis lupus_. Fox, _C. vulpes_. Otter, _Lutra vulgaris_. Urus, _Bos primigenius_. Bison, _Bison priscus_. Irish Elk, _Cervus megaceros_. Stag, _C. elaphus_. Brown’s Fallow Deer, _C. Browni_. Roedeer, _C. capreolus_. Musk Sheep, _Ovibos moschatus_. _Elephas antiquus._ Mammoth, _E. primigenius_. Horse, _Equus caballus_. Woolly Rhinoceros, _Rhinoceros tichorhinus_. _R. hemitœchus._ _R. megarhinus._ Wild-boar, _Sus scrofa_. Hippopotamus, _Hippopotamus amphibius_. Beaver, _Castor fiber_. Water-Rat, _Arvicola amphibia_. The discovery of a flint-flake in the undisturbed lower brick-earths of Crayford, by the Rev. O. Fisher, in the presence of the writer, in April 1872, proves that man was living while these fluviatile strata were being deposited. If these mammalia be compared with those of the forest-bed or the pleiocene age on the one hand, and with the late pleistocene on the other, it will be seen that they are linked to the former by _Rhinoceros megarhinus_, and to the latter by the musk sheep. The presence of the latter, the most arctic of the herbivores, in such strange company is most abnormal, and suggests the idea that the remains belong to two distinct eras. The skull, however, which I found at Crayford in 1867, and presented to the Museum of the Geological Survey, rested in intimate association with the bones of other species, is in the same mineral state, and bears no marks of being a “derived fossil.” It is the only trace of the animal as yet obtained from the lower brick-earths. The absence of the reindeer, so numerous in the valley of the Thames, while the late pleistocene strata were being accumulated by the river, and the abundance of remains of the stag, seem to me to point backwards rather than forwards in time, and to imply that the lower brick-earths are not of late pleistocene age; just as the absence of the characteristic early pleistocene species shows that they are not of that age. The evidence seems to be sufficient to establish a stage intermediate between the two. Nevertheless, it is sufficiently conflicting to cause Dr. Falconer to come to the conclusion that these strata are of pleiocene date, and Mr. Prestwich to believe that they belong to a late stage in the pleistocene.