Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/355

 Rh plants, while their earliest fossil representatives appear to have attained the dimensions of Forest Trees.

Existing Lycopodiaceæ follow nearly the same law as ferns and Equisetaceæ, in respect of geographical distribution; being largest and most abundant in hot and humid situations within the Tropics, especially in small islands. The belief that Lepidodendra were allied to the Lycopodiaceæ, and their size, and abundant occurrence among, the fossils of the Coal Formation have led writers on fossil plants to infer that great heat, and moisture, and an insular Position were the conditions, under which the first forms of this family attained that gigantic stature, which they exhibit in deposites, of the Transition period; thus corroborating the conclusion they had derived from the Calamites associated with them, as already mentioned.

Lindley and Hutton state, that Lepidodendra are, after Calamites, the most abundant class of fossils in the Coal formation of the North of England; they are sometimes of enormous size, fragments of stems occurring from twenty to forty-five feet long; in the Jarrow colliery a compressed tree of this class measured four feet two inches in breadth.