In the studies which have been made as preliminary to this paper, I have had great assistance from Mr. James C. Pilling and Mr. Henry W. Henshaw. Mr. Pilling began by preparing a list of papers used by me, but his work has developed until it assumes the proportions of a great bibliographic research, and already he has published five bibliographies, amounting in all to about 1,200 pages. He is publishing this bibliographic material by linguistic families, as classified by myself in this paper. Scholars in this field of research will find their labors greatly abridged by the work of Mr. Pilling. Mr. Henshaw began the preparation of the list of tribes, but his work also has developed into an elaborate system of research into the synonymy of the North American tribes, and when his work is published it will constitute a great and valuable contribution to the subject. The present paper is but a preface to the works of Mr. Pilling and Mr. Henshaw, and would have been published in form as such had not their publications assumed such proportions as to preclude it. And finally, it is needful to say that I could not have found the time to make this classification, imperfect as it is, except with the aid of the great labors of the gentlemen mentioned, for they have gathered the literature and brought it ready to my hand. For the classification itself, however, I am wholly responsible. I am also indebted to Mr. Albert S. Gatschet and Mr. J. Owen Dorsey for the preparation of many comparative lists necessary to my work. The task of preparing the map accompanying this paper was greatly facilitated by the previously published map of Gallatin. I am especially indebted to Col. Garrick Mallery for work done in the early part of its preparation in this form. I have also received assistance from Messrs. Gatschet, Dorsey, Mooney and Curtin. The final form which it has taken is largely due to the labors of Mr. Henshaw, who has gathered many important facts relating to the habitat of North American tribes while preparing a synonymy of tribal names. * * * * * INDEX A.