The great number of letters received from distinguished scholars in all parts of the world, from Edinburgh to New South Wales, attests the interest felt in this treatise, and at the same time places the author under obligations which words cannot express. Special acknowledgments are due to:— Professor W. ROBERTSON SMITH, Editor of the Encyclopædia Britannica. Major-General J. G. FORLONG, author of “The Rivers of Life,” Edinburgh. HAVELOCK ELLIS, Esq., Editor of the Contemporary Science Series. Prof. TYRRELL S. LEITH, of Bombay (since dead). FRANK REDE FOWKE, Esq., South Kensington Museum, London. JAMES G. FRAZER, Esq., M. A., author of “The Golden Bough,” Trinity College, Cambridge. Dr. GUSTAV JAEGER, of Stuttgart. Dr. J. W. KINGSLEY, of Cambridge. Prof. E. B. TYLOR, Oxford. Prof. E. N. HORSFORD, Harvard University. Prof. F. W. PUTNAM, Peabody Archæological Museum, Cambridge, Mass. Surgeon WASHINGTON MATTHEWS, U. S. Army. Surgeon B. J. D. IRWIN, U. S. Army. F. B. KYNGDON, Esq., Secretary Royal Society, Sydney, New South Wales. J. F. MANN, Esq., Sydney, New South Wales. JOHN FRAZER, Esq., LL.D., Sydney, New South Wales. Capt. HENRI JOUAN, French Navy. Dr. BERNARD, Cannes, France. Dr. ROBERT FLETCHER. Dr. FRANZ BOAS, Clark University, Worcester, Mass. Dr. HENRY STRICKER, Frankfort, Germany. Chief Engineer MELVILLE, U. S. Navy. Prof. OTIS T. MASON, National Museum, Washington, D. C. WILLIAM H. GILDER, the Arctic explorer and writer. Dr. ALBERT S. GATSCHET, Bureau of Ethnology, Washington, D. C. Rev. HENRY CLAY TRUMBULL, Editor of “The Sunday School Times,” of Philadelphia, Penn. Hon. LAMBERT TREE, ex-minister to Russia. ANDREW LANG. J. S. HITTEL, San Francisco, Cal. M. M. H. GAIDOZ, editor of “Mélusine,” Paris. Dr. S. B. EVANS, Ottumwa, Ia. Rev. J. OWEN DORSEY, Bureau of Ethnology, Washington, D. C. Mr. W. W. ROCKHILL, the distinguished Oriental scholar and explorer. Hon. H. T. ALLEN, Secretary Corean Legation. Mrs. F. D. BERGEN, and many other correspondents. Last, but not least, to Dr. J. HAMPDEN PORTER, of the city of Washington, whose friendly offices amounted practically to a collaboration.