The Quadrupeds came in in some force; not developed from the lowest to the highest scale of organization; for the Monkey and the Bat occur in sands, certainly not later, if not earlier, than the London Clay, contemporaneously with the Racoon, and before the existence of any Rodent or Cetacean. Some Carnivora, as the Wolf and the Fox, roamed the woods, but the character of the epoch was given by the Pachyderms. These, however, were not the massive colossi that browse in the African or Indian jungles of our days; no Elephant, no Rhinoceros, no Hippopotamus was as yet formed. But several kinds of Tapir wallowed in the morasses; and a goodly number of largish beasts, whose affinities were with the Pachydermata, while their analogies were with the Ruminantia, served as substitutes for the latter order, which was wholly wanting. These interesting quadrupeds, forming the genus _Anoplotherium_, were remarkable for two peculiarities,--their feet were two-toed, and their teeth were ranged in a continuous series, without any interval between the incisors and the molars. They varied in size from that of an ass to that of a hare. The physical conditions of our earth, when it was tenanted by these creatures, is thus described:--"All the great plains of Europe, and the districts through which the principal rivers now run, were then submerged; in all probability, the land chiefly extended in a westerly direction, far out into the Atlantic, possibly trending to the south, and connecting the western shores of England with the volcanic islands off the west coast of Africa. The great mountain chains of Europe, the Pyrenees, the Alps, the Apennines, the mountains of Greece, the mountains of Bohemia, and the Carpathians, existed then only as chains of islands in an open sea. Elevatory movements, having an east and west direction, had, however, already commenced, and were producing important results, laying bare the Wealden district in the south-east of England. The southern and central European district, and parts of western Asia, were the recipients of calcareous deposits (chiefly the skeletons of _Foraminifera_), forming the Apennine limestone; while numerous islands were gradually lifted above the sea, and fragments of disturbed and fractured rock were washed upon the neighbouring shallows or coast-lines, forming beds of gravel covering the Chalk. The beds of Nummulites and Miliolites, contemporaneous with those containing the Sheppey plants and the Paris quadrupeds, seem to indicate a deep sea at no great distance from shore, and render it probable that there were frequent alternations of elevation and depression, perhaps the result of disturbances acting in the direction already alluded to.