The rocks of the Paris basin display so clearly an orderly arrangement, and are so distinguished for the variety and perfect preservation of their enclosed organic remains, that they could not fail to attract the early notice of observers. J. E. Guettard, G.F. Rouelle (1703-1770), N. Desmarest, A.L. Lavoisier (1743-1794) and others made observations in this interesting district. But it was reserved for Cuvier (1769-1832) and A. Brongniart (1770-1847) to work out the detailed succession of the Tertiary formations, and to show how each of these is characterized by its own peculiar assemblage of organic remains. The later progress of investigation has slightly corrected and greatly amplified the tabular arrangement established by these authors in 1808, but the broad outlines of the Tertiary stratigraphy of the Paris basin remain still as Cuvier and Brongniart left them. The most important subsequent change in the classification of the Tertiary formations was made by Sir Charles Lyell, who, conceiving in 1828 the idea of a classification of these rocks by reference to their relative proportions of living and extinct species of shells, established, in collaboration with G.P. Deshayes, the now universally accepted divisions Eocene, Miocene and Pliocene. Long before Cuvier and Brongniart published an account of their researches, another observer had been at work among the Secondary formations of the west of England, and had independently discovered that the component members of these formations were each distinguished by a peculiar group of organic remains; and that this distinction could be used to discriminate them over all the region through which he had traced them. The remarkable man who arrived at this far-reaching generalization was William Smith (1769-1839), a land surveyor who, in the prosecution of his professional business, found opportunities of traversing a great part of England, and of putting his deductions to the test. As the result of these journeys he accumulated materials enough to enable him to produce a geological map of the country, on which the distribution and succession of the rocks were for the first time delineated. Smith's labours laid the foundation of stratigraphical geology in England and he was styled even in his lifetime the "Father of English geology." From his day onward the significance of fossil organic remains gained rapidly increasing recognition. Thus in England the outlines traced by him among the Secondary and Tertiary formations were admirably filled in by Thomas Webster (1773-1844); while the Cretaceous series was worked out in still greater detail in the classic memoirs of William Henry Fitton (1780-1861).