My plan has been to deal in some detail with certain selected types, and to refer briefly to such others as should be studied by anyone desirous of pursuing the subject more thoroughly, rather than to cover a wide range or to attempt to make the list of types complete. Of late years there has been a much wider interest evinced by Botanists in the study of fossil plants, and this is in great measure due to the valuable and able work of Graf zu Solms-Laubach. His _Einleitung in die Palaeophytologie_ must long remain a constant book of reference for those engaged in palaeobotanical work. While referring to authors who have advanced the study of petrified plants of the Coal period, one should not forget the valuable services that have been rendered by such men as Butterworth, Binns, Wilde, Earnshaw, Spencer, Nield, Lomax and Hemingway, by whose skill the specimens described by Williamson and others were first obtained and prepared for microscopical examination. I am indebted to many friends, both British and Continental, for help of various kinds. I would in the first place express my thanks to Professor T. McKenny Hughes for having originally persuaded me to begin the study of recent and fossil plants. I am indebted to Prof. Nathorst of Stockholm, Dr Hartz of Copenhagen, Prof. Zeiller, Dr Renault and Prof. Munier-Chalmas of Paris, Prof. Bertrand of Lille, Prof. Stenzel and the late Prof. Roemer of Breslau, Dr Sterzel of Chemnitz, the late Prof. Weiss of Berlin, the late Dr Stur of Vienna, and other continental workers, as well as to Mr Knowlton of Washington, for facilities afforded me in the examination of fossil plant collections. My thanks are due to the members of the Geological and Botanical departments of the British Museum; also to Mr E. T. Newton of the Geological Survey, and to those in charge of various provincial museums, for their never-failing kindness in offering me every assistance in the investigation of fossil plants under their charge. Prof. Marshall Ward has given me the benefit of his criticism on the section dealing with Fungi; and my friend Mr Alfred Harker has rendered me a similar service as regards the chapter on Geological History. I am especially grateful to my colleague, Mr Francis Darwin, for having read through the whole of the proofs of this volume. To Mr Shipley, as Editor, I am under a debt of obligation for suggestions and help in various forms. I would also express my sense of the unfailing courtesy and skill of the staff of the University Press. My friend Mr Kidston of Stirling has always generously responded to my requests for the loan of specimens from his private collection. Prof. Bayley Balfour of Edinburgh, Mr Wethered of Cheltenham and others have assisted me in a similar manner. I would also express my gratitude to Dr Hoyle of Manchester, Mr Platnauer of York, and Mr Rowntree of Scarborough for the loan of specimens.