"These vegetables appear even at the beginning of the Chalk formation; for it is certain that many well-determined species exist in the quadersandstein and planerkalk of Germany, which appear to correspond to the green sandstone of France, or green sand of English geologists; although this formation in France and England has never yielded any of them, but only some examples of Cycadeæ, Coniferæ, and marine plants. But in southern Sweden, at Kopingue in Scania, some specimens of dicotyledonous leaves appear associated with a species of Cycadeæ, in beds which have been referred to the greensand; so that the whole Chalk formation would appear to constitute a first period in the reign of the Angiosperms, forming, so to speak, the passage between the vegetation of the Secondary and that of the Tertiary formations, still presenting, as the first, a few Cycadeæ, as the following, some Angiospermous dicotyledons, and thus paving the way to the considerable development of these vegetables in the succeeding period. This period is besides characterised by many Coniferæ peculiar to it, and which appear very distinct from those of the Wealdean formations, and from those of the Eocene epoch of the Tertiary formations; and such in particular are the Cunninghamites.
"We can therefore distinguish two great periods in the reign of the Angiosperms:
"1st, The Cretaceous period, a kind of period of transition.
"2dly, The Tertiary period, presenting all the characters arising from the predominance of Angiosperms, Dicotyledons, and Monocotyledons, and divisible into many epochs, the characters of which will not be well established until we have removed all doubts as to the agreement of the different local series of the Tertiary formations.
"V. Cretaceous Period.—The Cretaceous period, properly so called, comprehends perhaps many distinct epochs; but the beds where fossil vegetables have been observed, not having been always classified with precision in the different subdivisions of this formation, it is impossible to establish their chronology with certainty. Besides, we must distinguish an epoch which appears immediately to precede this formation, and one which follows it, and yet differs from the Eocene period.
"We are acquainted with fossil vegetables of the Cretaceous period:—
"1st, Sub-Cretaceous Epoch.—In the subcretaceous marine lignites of the Isle of Aix, near La Rochelle, and of Pialpinson, in the department of the Dordogne; these are the most ancient beds of the Cretaceous formation, or the last of the Jurassic period. Here have been found only marine plants, wood, and branches of Coniferæ.
"2d, In the chloriteous chalk or greensand of southern England, the neighbourhood of Beauvais and Maus; only Cycadeæ and marine plants have been observed there.
"3d, In the same formation in Scania, where M. Nilson has observed leaves of Dicotyledons mixed with leaves of Cycadites.
"4th, At Niederschœna, near Freyberg, in Saxony, beds, analogous to greensand or quadersandstein, containing fossils of considerable variety, Cycadeæ, Coniferæ, and Dicotyledons, particularly Credneria.