[1] Miller's Footprints of the Creator, 192-199. Doubts have been thrown on the antiquity of this specimen by those who support the erroneous progressive development theory; but the presence, in the same nodule, of a scale of a fish only found in the lower Old Red, puts the matter beyond doubt. Dr. M'Nab on the Structure of a Lignite (PalÆopitys) from the Old Red Sandstone. (Trans. Bot. Soc. x. p. 312.)

[2] Specimens of these fossil plants, as well as numerous others, illustrating the fossil flora of Scotland, are to be seen in Mr. Miller's collection, now in the Edinburgh Museum of Science and Art.

[3] Dawson, Jour. Geol. Soc. Lond. xv. Canadian Naturalist, v. Acadian Geology, 2d edit. Fossil plants of the Devonian and upper Silurian Formations of Canada, with 20 plates; in Report of Geological Survey of Canada.

[4] Maclaren, Geology of Fife and the Lothians, p. 116.

[5] Our Coal-fields, by a Traveller under Ground.

[6] See Hall's Coal-fields of Great Britain, 1861; Roscoe's Lectures on Coal, Manchester, 1866-67; Hunt's Mineral Statistics of Great Britain; Taylor's Statistics of Coal, 1855-56.

[7] Heer, Flora fossilis Arctica; Fossile Flora der BÄren Insel., 1871.

[8] In giving names to fossil Ferns, the Greek word pte???, meaning a Fern, is often used with a prefix indicating some character in the form of the leaves, or stem, or fructification: such as, p????, a comb; ?e????, a nerve; ?d???, a tooth; sf??, a wedge; ?a????, a stalk or stem; ??????, a circle; s????, a split, etc.

[9] The imbedding of plants in an erect state in strata is similar to what was noticed at the present day by Gardner in Brazil, where stems of recent Coco-nut Palms were seen covered with sand to the depth of 50 feet.

[10] For woodcuts 44, 47, and 48, I am indebted to Dr. H. Bence Jones, who has kindly placed them at my disposal. They were used to illustrate Mr. Carruthers' remarks on the Cryptogamic forests of the Coal period, published in the Journal of the Royal Institution of Great Britain, April 16, 1869. Mr. Carruthers' observations are given in the text.

[11] Conjugate spirals result from whorls of usually 2, 3, 5, 8, etc., leaves arranged so as to give 2, 5, 8, etc., parallel spirals, each with an angular divergence equal to ½, ?, ?, ?, etc., of one of the fractions expressing the divergence in an arrangement of alternate leaves.

[12] By inadvertence, the diameter is stated in my Class-book as 4-5 inches.

[13] See Remarks on the Structure of Calamites by W. C. Williamson, Philos. Trans., 161, p. 477.

[14] Williamson on the Structure and Affinities of SternbergiÆ, in Manch. Lit. and Phil. Soc. Mem. ix. Dawson on Sternbergia, in Edin. New Phil. Journ., new series, vii. 140.

[15] See Notice of Antholithes PitcairniÆ, by C. W. Peach, in Bot. Soc. Trans. Edin. vol. xi.

[16] See Professor Duns on the association of Cardiocarpum with Sphenopteris. Proc. R.S.E., April 1, 1872.

[17] See Meyer's PalÆontographica, Cassel, 1864.

[18] See fuller description of ConiferÆ and CycadaceÆ in Balfour's Class Book of Botany, pp. 906-912.

[19] Coal in the Kimmeridge clay is probably of animal origin.

[20] Carruthers, Geol. Mag., vol. viii. December 1871.

[21] Annals and Mag. of Nat. Hist. 2d ser. ii. 380.

[22] Journ. Geol. Soc. of London, vii.

[23] Philosophical Transactions, R. Soc. Lond., vol. clii. p. 1039.

[24] Heer, Flore Fossile des Regions Polaires, Zurich; also Bibliotheque Univ. xxxix. p. 12; see also Ann. Nat. Hist. 4th ser. i. 61, iv. 81.

[25] Raulin, Sur les Transformations de la Flore de l'Europe centrale pendant la pÉriode Tertiaire.—Ann. des Sc. Nat. 3d ser. Bot. x. 193.