The scientific reputation of the Expedition will rest upon the technical reports of its work which will be published in due course by the American Museum of Natural History. To these reports we would refer those readers who desire more complete information concerning the results of our researches. At the time the manuscript of this volume was sent to press the collections were still undergoing preparation and the study of the different groups had just begun. Although the book has been largely written by the senior author, his collaborator has contributed six chapters marked with her initials; all the illustrations are from her photographs and continual use has been made of her daily journals; she has, moreover, materially assisted in reference work and in numerous other ways. The information concerning the relationships and distribution of the native tribes of Yün-nan is largely drawn from the excellent reference work by Major H.R. Davies and we have followed his spelling of Chinese names.