"The essential characters of this epoch are therefore, _1st_, The great predominance of Cycadeæ, already well established, and the presence of numerous genera in this family, particularly _Zamites_ and _Nilsonia_; _2d_, The existence of many genera among the ferns with reticulated nerves, which scarcely shew themselves, and under forms not greatly varied, in the most ancient formations; but some of which, notwithstanding, already begin to appear in the epoch of the Keuper. Such are the _Camptopteris_ and _Thaumatopteris_. "_Oolitic Epoch._--The Oolitic epoch furnishes, among Amphigenous cryptogams, the Algæ; among the Acrogenous cryptogams, Ferns, Marsileaceæ, Lycopodiaceæ, and Equisetaceæ; among the Gymnospermous dicotyledons, Cycadeæ and Coniferæ; lastly, among the doubtful monocotyledons, Podocarya and Carpolithes. "This list is chiefly founded on the fossils, so varied in character, collected on the coasts of Yorkshire, near Whitby and Scarborough, in beds which are referred to different parts of the inferior oolite, and particularly to the great oolite. It likewise contains a small number of species found in the slaty limestone of Stonesfield, near Oxford, depending on these same beds. "In France, the fossils of this formation have been collected in the neighbourhood of Morestel, near Lyon, by Dr Lortet; at Orbagnoux and Abergemens, near Nantua, in the department of the Ain, by M. Itier; in the vicinity of Chateauroux, near Châtillon-sur-Seine, by Colonel Moret; at Mamers, in the department of Sarthe, by M. Desnoyers; and, lastly, in the greatest quantity by M. Moreau, in beds of oolithic limestone of a very pure white, in the neighbourhood of Verdun, and near Vaucouleurs. Some species have likewise been found at other points of the Jura, in Normandy, near Valogne, in the neighbourhood of Alençon, in each of these localities in very small number. But the greater part of these species are not yet described and figured, and they generally differ as species from those of England. The ferns are generally less numerous, and not so well preserved; we must, however, except the _Hymenophyllites macrophyllus_, found in a perfect state at Morestel, and likewise observed at Stonesfield, and in Germany. The Cycadeæ, the species of which are not greatly varied, are referrible to the genera _Otozamites_ and _Zamites_; Ctenis, Pterophyllum, and Nilsonia have not yet been observed; lastly, the Coniferæ of the genus _Brachyphyllum_ are there particularly abundant, and more frequent than in the other localities. "In Germany, it is more especially in the slaty limestone of Solenhofen, near Aichstædt, that these fossils have been observed, and particularly those of the family of Algæ. M. Gæppert likewise notices many Cycadeæ in the Jurassic formation of Ludwigsdorf, near Kreuzburg, in Silesia.