^{page 643 note *} Trans. Roy. Soc. Edin., vol. li, p. 761, and vol. lii, p. 603.

^{page 643 note †} Mackie, W., “The Rock Series of Craigbeg and Ord Hill, Rhynie, Aberdeenshire”, Trans. Edin. Geol. Soc., vol. x, pp. 205–236Google Scholar, pl. xxiii.

^{page 644 note *} Mackie, W., “The Rook Series of Craigbeg and Ord Hill, Rhynie, Aberdeenshire”, Trans. Edin. Geol. Soc., vol. x, pp. 205–236Google Scholar, pl. xxiii, fig. 6.

^{page 644 note †} It may assist the reader in forming an idea of the vegetative organs of Asteroxylon if we note at the outset the parallel afforded by the Psilotaceæ, in which the plant has a leafless, cylindrical, subterranean rhizome of simple structure, certain branches of which pass into the more complex aerial leafy shoots. There are also resemblances in structure between the leafy shoot of Asteroxylon and that of the Psilotaceæ, but the most helpful parallel as regards the anatomy is found in some species of Lycopodium.

^{page 647 note *} The question as to the saprophytie or possible mycorhizal nature of this fungus is deferred to Part IV, in which the fungi present inthe peat-bed will be considered.

^{page 654 note *} This particular stem was undergoing branching of a peculiar endogenous type, as will be described below.

^{page 665 note *} See Part I, Trans. Roy. Soc., Edin., voL li, p. 780, 1917.

^{page 667 note *} Hollowat, J. E., “The Prothallus and YoungPlant of Tmesipteris”, Train. N.Z. Institute, vol 1, 1917.Google Scholar

^{page 668 note *} The protoxylem of Lycopodium is usually exarch, as it may also be in Asteroxylon. Where larger leaf-traces join the stem-xylem in some species of Lycopodiua mesarch structure is shown. (Cf. Sinnott, , “On Mesarch Structure in Lycopodium” Bot. Gazette, 48Google Scholar, pl. x, fig. 5.)

^{page 668 note †} Cf. Bertrand, P., Progressus Rei Botanicae, Bd. iv, p. 276Google Scholar

^{page 668 note ‡} The vascular structure of Stauropteris will evidently be regarded differently according to whether it is assumed that it is a specialised Zygopteridean frond (Bertband, P., Études sur la Fronde des Zygopteridées, Lille, 1909)CrossRefGoogle Scholar, or that it is a plant of more archaic type than the Zygopterideæ, though tending in their direction (Lignier, , Bull. Soc. Bot. de France, t. 59 (1912), p. 1).CrossRefGoogle Scholar

^{page 669 note *} Geological History of Plants, fig. 19.

^{page 669 note †} Halle, T. G., “Lower Devonian Plants from Röragen in Norway”, Kungl. Svmska Vetenskapsakademiens Handlingar, Bd. 57 (1916), p. 1.Google Scholar

^{page 670 note *} Flore Devonienne de l'Étage H. de Barrdnde, p. 32, figs. 71–72.

^{page 670 note †} Nathorst, , “Zur Devonflora des westlichen Norvegens”, Bergens Museum Aarbok, 1914-1915 No. 9.Google Scholar

^{page 670 note †} Ibid., Taf. 3, figs. 5–7; Taf. 4, figs. 4–9.

^{page 671 note *} Schmalhausen, J., “Ueber devonische Pflanzen aus dem Donetz-Becken”, Mém. du Gomié Géol., vol. viii No. 3, p. 29, 1894.Google Scholar

^{page 671 note †} Crépins, F., “Description de quelques plan tea fossiles de Péetage des Psamraites du Condroz (Dévonien Supérieur)”, Bull. de l'Acad. roy. de Belgique, vol. xxxviii, p. 1, 1874. (Psilophyton condrusorum.)Google ScholarCrépin, F., “Observations sur quelques plantes fossiles de dépôts dévonien, etc”., Bull. Soc. roy. de Botan. de Belgique, vol. xiv, p. 224, 1875. (Footnote, Rhacophyton condrusorum.)Google Scholar

^{page 671 note ‡} Loc. cit., 1912.

^{page 672 note *} Lignier, M.O., “Equisétales et Sphénophyllales: Leur origine filicinéene commune”, Bull. Soc. Linn. Normandie, sér. 5, vol. 7, 1903, p. 93.Google Scholar “Essai sur l'Évolution Morphologique du regne végétal”, Comptes de l'Assoc. Française pour l'Avancement des Sciences, 1908, p. 580. “Le Stauropteris Oldhamia Binney et les Coenoptéridées à la lumière de la théorie du mériphyte”, Bull. Soc. Bot. de France, t. 59, 1912, p. 1.

Halle, T. G., “Lower Devonian Plants from Roragen in Norway,” Kungl. Svenska Vetenskapsakad. Handlingar, Bd. 57, p. 1.Google Scholar

^{page 672 note †} Lectures on the Evolution of the Filicinean Vascular System, p. 9. (Reprint, 1908.)

^{page 672 note ‡} For the present purpose it is unnecessary to complicate the discussion by entering into the consideration of the Equisetales and Sphenophyllales.

^{page 677 note *} In this and the preceding figure the soft tissues have been lost in the photograph in bringing out the details of the xylem.