are a matter of authority, it is believed that the references to the Notes will be found fully to cover them; and where illustrations are the subject, the derivation is indicated on the tissues. In the way of courtesies extended, the author owes recognition to staff-members of the libraries of Harvard and Northwestern Universities, to the Peabody Museum, the Boston Museum of Fine Arts, the American Museum of Natural History, and the Museum of the University of Nebraska. His personal obligations are due to Professor Frank S. Philbrick, of the Northwestern University Law School, and to the Assistant Curator of the Academy of Pacific Coast History, Dr. Herbert I. Priestley, for valuable suggestions anent the bibliography, and to Dr. Hiram Bingham, of the Yale Peruvian Expedition, for his courtesy in furnishing for reproduction the photographs represented by Plates XXX and XXXVIII. His obligations to the editor of the series are, it is trusted, understood.
The manuscript of the present volume was prepared for the printer by November of 1916. The ensuing outbreak of war delayed publication until the present hour. In the intervening period a number of works of some importance appeared, and the author has endeavoured to incorporate as much as was essential of this later criticism into the body of his work, a matter difficult to make sure. The war also has been responsible for the editor's absence in Europe during the period in which the book has been put throtigh the press, and the duty of oversight has fallen upon the author who is, therefore, responsible for such editorial delinquencies as may be found.
Lincoln, Nebraska,
November 17, 1919.
