^{page 761 note *} Mackie, W., “The Rock Series of Craigbeg and Ord Hill, Rhynie, Aberdeenshire,” Trans. Edin. Geol. Soc., vol. x, pp. 205–236, pl. xxiiGoogle Scholar.

^{page 761 note †} Mackie, l.c., pl. xxiii, fig. 5.

^{page 761 note ‡} Mackie, l.c., pl. xxiii, fig. 6.

^{page 761 note §} Mackie, l.c., p. 223.

^{page 762 note *} The exact horizon of the Rhynie Old Red Sandstone has not yet been definitely determined, but it cannot be younger than the Middle Old Red Sandstone.

^{page 762 note †} The site of this trench is shown on the map (fig. 1) in the Report of the Committee on “The Plant–bearing Cherts at Rhynie, Aberdeenshire,’ Brit. Assoc. Rep., 1916, Newcastle Meeting.

^{page 763 note *} This column gives the original numbers of the specimens as collected.

^{page 765 note *} Such impressions, with or without an evident midrib, according to their preservation, might easily be described as linear leaves or even algæ.

^{page 765 note †} The stems in Pl. II, fig. 5, measured 6 inches, but were incomplete.

^{page 766 note *} The peculiar oval bodies in the cortex of the two lowest rhizomes in fig. 13 are the reproductive organs of saprophytic fungi. The detailed description of the numerous fungi which occur in the deposit is reserved for a future communication, but the reader must allow for their presence in many of the illustrations to this paper.

^{page 776 note *} The primitive nature of the general organisation of the Psilotacese is clearly held on other grounds by C. Eg. Bertrand, in his Recherches sur les Tmesipteridées, Lille, 1883, pp. 313–316;Google Scholar and by Lignier, in his “Equisétales et Sphénophyllales leur origine filicinéenne commune,” p. 95, Bull. Soc. Linn, de Normandie, 5^e sér., vol. vii, 1903, p. 93, CaenGoogle Scholar.

^{page 776 note †} Geological Survey Canada, Montreal, 1871Google Scholar.

^{page 777 note *} It will be observed that we exclude from Psilophyton princeps Dawson's figures of “rhizomes,” pl. x, figs. 111, 115, 116, and 117. We also exclude at present from Psilophyton all the other species which have been referred to it by Dawson and other writers, as they do not seem to show the characters necessary for their definite reference to this genus.

^{page 777 note †} The course we adopt is in general agreement with the views of Solm–Laubach, Fossil Botany, pp. 189–192, and more recently of Bertrand, P. in “Note preliminaire sur les Psilophytons des grès de Matringhen,” Ann. Soc. géol. du Nord, vol. xlii, p. 157,Google Scholar 1913.

^{page 777 note ‡} L.c., pl. xi, figs. 133 and 134.

^{page 777 note §} L.c., pl. xi, fig. 127.

^{page 777 note ∥} L.c., p. 37.