plants, while their earliest fossil representatives appear to have attained the dimensions of Forest Trees.[1]
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.[2]
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.
- ↑ Prof. Lindley states that the affinities of existing Lycopodiaceæ are intermediate between Ferns and Coniferæ on the one hand, and Ferns and Mosses on the other; They are related to Ferns in the want of sexual apparatus, and in the abundance of annular ducts contained in their axis; to Coniferæ, in the aspect of the stems of some of the larger kinds; and to Mosses in their whole appearance.
- ↑ The leaves of existing Lycopodiaceæ are simple, and arranged in spiral lines around the stem, and impress on its surface scars of rhomboidal or lanceolate form, marked with prints of the insertions of vessels, In the fossil Lepidodendra, we find a large and beautiful variety of similar scars, arranged like scales in spiral order, over the entire surface of the stems. A large division of these are arborescent and dichotomous, and have their branches covered with simple lanceolate leaves. Our figure of Lepidordendron Sternbergii (Pl. 55. Figs. 1. 2. 3.) represents all these characters in a single Free from the Coal mines of Swina in Bohemia.
The form of the scales varies at different parts of the same stem, those nearest the base are elongated in the vertical direction.
