[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 πτερίς, meaning a Fern, is often used with a prefix indicating some character in the form of the leaves, or stem, or fructification: such as, πέκος, a comb; νεῦρον, a nerve; ὀδούς, a tooth; σφήν, a wedge; καυλός, a stalk or stem; κύκλος, a circle; σχίζω, 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, ⅓, ⅕, ⅛, 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.