Of course, the chapters of the present volume relating to America cover much of the same ground gone over in the previous treatise; but the matter has been entirely rewritten and very much condensed, so as to give due proportions to all parts of the subject. It will interest some to know that most of the new material in this volume was first wrought over in my second course of Lowell Institute Lectures, given in Boston during the month of March last. I am under great obligations to Mr. Charles Francis Adams for his aid in prosecuting investigations upon the Pacific coast of America; and also to Dr. H. W. Crosskey, of Birmingham, England, and to Mr. G. W. Lamplugh, of Bridlington, as well as to Mr. C. E. De Rance and Mr. Clement Reid, of the British Geological Survey, besides many others in England who have facilitated my investigations; but pre-eminently to Prof. Percy F. Kendall, of Stockport, who consented to prepare for me the portion of Chapter VI which relates to the glacial phenomena of the British Isles. I have no doubt of the general correctness of the views maintained by him, and little doubt, also, that his clear and forcible presentation of the facts will bring about what is scarcely less than a revolution in the views generally prevalent relating to the subject of which he treats. For the glacial facts relating to France and Switzerland I am indebted largely to M. Falsan's valuable compendium, La Période Glaciaire. It goes without saying, also, that I am under the deepest obligation to the works of Prof. James Geikie upon The Great Ice Age and upon Prehistoric Europe, and to the remarkable volume of the late Mr. James Croll upon Climate and Time, as well as to the recent comprehensive geological treatises of Sir Archibald Geikie and Prof. Prestwich. Finally, I would express my gratitude for the great courtesy of Prof. Fraipont, of Liége, in assisting me to an appreciation of the facts relating to the late remarkable discovery of two entire skeletons of Paleolithic man in the grotto of Spy. Comparative completeness is also given to the volume by the appendix on the question of man's existence during the Tertiary period, prepared by the competent hand of Prof. Henry W. Haynes, of Boston. I trust this brief treatise will be useful not only in _interesting_ the general public, but in giving a clear view of the present state of progress in one department of the inquiries concerning man's antiquity. If the conclusions reached are not as positive as could be wished, still it is both desirable and important to see what degree of indefiniteness rests upon the subject, in order that rash speculations may be avoided and future investigations directed in profitable lines. G. Frederick Wright. Oberlin, Ohio, _May 1, 1892_. CONTENTS. PAGES CHAPTER I. Introductory 1-8