Nine years afterwards, when these fossil Pachyderms had been found in the London clay, and in the sandy strata at its base, the remains of a monkey, of the genus Macacus, were detected near Woodbridge, in Suffolk; and other Quadrumana had been met with, a short time previously, in different stages of the tertiary series, in India, France, and Brazil. When we consider the small area of the earth's surface hitherto examined geologically, and our scanty acquaintance with the fossil Vertebrata, even of the environs of great European capitals, it is truly surprising that any naturalist should be rash enough to assume that the Lower Eocene deposits mark the era of the first creation of Quadrumana. It is, however, still more unphilosophical to infer from a single extinct species of this order, obtained in a latitude far from the tropics, that the Eocene Quadrumana had not attained as high a grade of organization as those of our own times, when the naturalist is acquainted with all, or nearly all, the species of monkeys, apes and orangs which are contemporary with man. To return to the year 1830, Mammalia had not then been traced to rocks of higher antiquity than the Stonesfield Oolite, whereas we have just seen that memorials of this class have at length made their appearance in the Trias of Germany. In 1830 birds had been discovered no lower in the series than the Paris gypsum, or Middle Eocene. Their bones have now been found both in England and the Swiss Alps in the Lower Eocene, and their existence has been established by foot-prints in the triassic epoch in North America (p. 297.). Reptiles in 1830 had not been detected in rocks older than the Magnesian limestone, or Permian formation; whereas the skeletons of four species have since been brought to light (see p. 336.) in the coal-measures, and one in the Old Red sandstone, of Europe, while the footprints of three or four more have been observed in carboniferous rocks of North America, not to mention the chelonian trail above described, from the most ancient of the fossiliferous rocks of Canada, the "Potsdam Sandstone," which lies at the base of the Lower Silurian system. (See above, p. vii.) Lastly, the remains of fish, which in 1830 were scarcely recognized in deposits older than the coal, have now been found plentifully in the Devonian, and sparingly in the Silurian, strata; though not in any formation of such high antiquity as the Chelonian of Montreal.