xviii PREFACE 



The selected bibliographies which are appended after 

 each chapter constitute the best works on specific points 

 discussed in the course of the chapter. 



The- author's indebtedness to Professor Franklin H. 

 Giddings for encouragement and stimulating suggestions 

 is greater than can be expressed in a formal preface. 

 But the author wishes to express his appreciative thanks 

 to Dr. Giddings for permission to use unpublished 

 material, for reading the manuscript, and for making 

 many criticisms and suggestions which have been of 

 greatest service. 



The author's thanks are also due Professor Leonard 

 S. Blakey and Mr. B. J. Baldwin for reading parts of the 

 manuscript and for suggesting the revision of certain 

 details. Acknowledgments and thanks are due the fol- 

 lowing authors for the courteous permission accorded to 

 copy and reproduce certain diagrams, maps and illustra- 

 tions from their works : Professor F. Birkner, Der Dilu- 

 viale Mensch in Europa; Professor Katharine Coman, 

 The Industrial History of the United States; Professor 

 Joseph Dechelette, Manuel D'Archeologie Prehistorique; 

 Dr. Robert Forrer, Urgeschichte des Europders; Pro- 

 fessor James Geikie, The Great Ice Age; Professor M. M. 

 Metcalf, Organic Evolution; Professor William Z. Ripley, 

 The Races of Europe; and Professor E. L. Thorndike, 

 Individuality. For extending the same courtesy the au- 

 thor wishes to thank the editors of L'Anthropologie, The 

 Open Court Publishing Company, and the editor Auguste 

 Picard. 



To the Century Company the author's thanks are due 

 for courtesy in furnishing many excellent illustrations 

 from the Century Magazine and other of their publica- 

 tions, and for cooperating with the author to secure the 



