TREFACE. Vll Sehvyn, Esq., Director of the Geological Survey of Canada, who placed at the Author’s disposal a number of engravings of Silurian and Devonian fossils, from the publications of the Survey. The Author has likewise to acknowledge a similar obligation to Principal Daw son, of M'Gill University, Montreal, who kindly per mitted the use of several of the illustrations of his ‘ Acadian Geology.’ A considerable proportion of the engravings, however, are taken from D’Orbigny’s beau tifully illustrated ‘ Cours Elementaire de Paleontologie,’ by an arrangement with the publishers of that work. University College, Toronto, October 16, 1872.