[Illustration: Fig. 19.--_Psilophyton princeps_, restored (Lower Erian, Gaspé). _a_, Fruit, natural size. _b_, stem, natural size, _c_, Scalariform tissue of the axis, highly magnified. In the restoration, one side is represented in vernation and the other in fruit.] Another genus, which I have named _Psilophyton_[AT] (Figs. 19, 21), may be regarded as a connecting link between the Rhizocarps and the Lycopods. It is so named from its resemblance, in some respects, to the curious parasitic Lycopods placed in the modern genus _Psilotum_. Several species have been described, and they are eminently characteristic of the Lower Erian, in which they were first discovered in Gaspé. The typical species, _Psilophyton princeps_, which fills many beds of shale and sandstone in Gaspé Bay and the head of the neighbouring Bay des Chaleurs with its slender stems and creeping, cord-like rhizomes, may be thus described: [AT] "Journal of the Geological Society," vols, xv., xviii., and xix., "Report on Devonian Plants of Canada," 1871. Stems branching dichotomously, and covered with interrupted ridges. Leaves rudimentary, or short, rigid, and pointed; in barren stems, numerous and spirally arranged; in fertile stems and branchlets, sparsely scattered or absent; in decorticated specimens, represented by a minute punctate scars. Young branches circinate; rhizomata cylindrical, covered with hairs or ramenta, and having circular areoles irregularly disposed, giving origin to slender cylindrical rootlets. Internal structure--an axis of scalariform vessels, surrounded by a cylinder of parenchymatous cells, and by an outer cylinder of elongated woody cells. Fructification consisting of naked oval spore-cases, borne usually in pairs on slender, curved pedicels, either lateral or terminal. [Illustration: Fig. 20.--_Sphenophyllum antiquum_ (Erian, New Brunswick). See pp. 61, 67.]