Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/354

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In strata of the Secondary Series, the absolute and relative numbers of species of Ferns considerably diminishes, forming scarcely one third of the known Flora of these midway periods of geological history. (See Pl. 1. Figs. 37. 38. 39.)

In the Tertiary Strata, Ferns appear to bear to other vegetables nearly the same proportion as in the temperate regions of the present Earth.

The genus Lepidodendron comprehends many species of fossil plants, which are of large size, and of very frequent occurrence in the Coal formation. In some points of their structure they have been compared to Coniferæ, but in other respects and in their general appearance, with the exception of their great size, they very much resemble the Lycopediaceæ, or Club Moss Tribe. (See Pl. 1. Figs. 9. 10.) This tribe at the present day, contains no species more than three feet high, but the greater part of them are weak, or creeping >br />of Angiopteris, the scars are either elliptic or rhomboidal, and have their longer diameter vertical.

M. Ad. Brongniart (Hist. des Veg. Foss. p. 261, Pl. 79. 80.) has described and figured the leaf and stem of an arborescent fern (Anomopteris, Mougeottii) from the variegated sand-stone of Heilegenberg in the Vosges. Beautiful leaves of this species, with their capsules of fructitication sometimes adhering to the pinnules, abound in the New red sandstone formation of this district.

M. Cotta has published an interesting Work on fossil Remains of arborescent ferns, which occur abundantly in the New red sand-stone of Saxony near Chemnitz. (Dendrolithen. Dresden and Leipsig, 1832.) These consist chiefly of sections of the Trunks of many extinct species, sufficiently allied in structure to that of existing arborescent Ferns, to leave little doubt that they are the remains of extinct species of arborescent Pfants of this family, that grew in Europe at this Period of the Secondary formation.