Fig. 44.—Lepidodendron Sternbergii restored. Forty feet high.
The Ferns differ chiefly in some of the details of the leaf. Pecopteris, for instance ([Fig. 48]), have the leaves once, twice, or thrice pinnatifid with the leaflets adhering either by their whole base or by the centre only; the midrib running through to the point. Neuropteris ([Fig. 49]) has leaves divided like Pecopteris, but the midrib does not reach the apex of the leaflets, but divides right and left into veins. Odontopteris ([Fig. 51]) has pinnatifid leaves, like the last, but its leaflets adhere by their whole base to the stalk. Lonchopteris ([Fig. 50]) has the leaves several times pinnatifid, the leaflets more or less united to one another, and the veins reticulated. Among the most numerous species of forms of the Coal-measure period was Sphenopteris artemisiæfolia ([Fig. 52]), of which a magnified leaf is represented. Sphenopteris has twice or thrice pinnatifid leaves, the leaflets narrow at the base, and the veins generally arranged as if they radiated from the base; the leaflets are frequently wedge-shaped.
Fig. 45.—Lepidostrobus variabilis.
