Another curious, and till recently little understood, group of Carboniferous trees is that known as _Cordaites_, which existed already in some of its species in the Devonian. Their leaves are long, and often broad as well, and with numerous delicate parallel veins, resembling in this the leaves of grasses. Corda long ago showed that one species at least has a stem allied to the Club-mosses. More recently Grand’ Eury has found in the South of France admirably preserved specimens, which show that others more resembled in their structure the Pines and Yews, and were probably Gymnosperms, approaching to the Pines, but with very peculiar and exceptional foliage, of which the only modern examples are the broad-leaved Pines of the genus _Dammara_ (Frontispiece to Chapter). Here again we have either two very distinct groups, combined through our ignorance, or a connecting link between the Lycopods and the Pines. [Illustration: FIG. 101.—_Trigonocarpum Hookeri_ (Dn.). A Gymnospermous seed. _a_, Testa. _b_, Tegmen. _c_, Nucleus. _d_, Embryo.] The Yews and their allies among modern trees, while members of the great Cone-bearing order, bear nut-like seeds in fleshy envelopes, sometimes, as in the Gínkgo of Japan, constituting edible fruits. Seeds of this type seem to have been extremely abundant in the Carboniferous age in all parts of the world, and were probably produced by trees of several genera (_Dadoxylon_, _Sigillaria_, _Cordaites_, etc.) (Fig. 101). Charles Brongniart has recently described no less than seventeen genera of these seeds from the coal-field of St. Étienne alone, and it would be a low estimate to say that we probably know as many as sixty or seventy species in all, while the trunks of great coniferous trees allied to Taxineæ, and showing well-preserved structure, are by no means uncommon in the Devonian and Carboniferous. Had these great Yews appeared for the first time in the Coal-formation, we might have supposed that they had been developed from such Lycopods as _Lepidodendra_, and that the _Cordaites_ are the intermediate forms; but unfortunately the Pines go almost as far back in geological time as the Lycopods, and it does not help us, when in search of evidence of evolution, to find the link which is missing or imperfect in the Early Devonian supplied in the Coal-formation, where, for this purpose at least, it is no longer needed.