Since 1929 most of the Spring and Summer months have been spent by the writer in field work, a large part of which was devoted to investigations in caves and shelters in the Guadalupe Mountains of New Mexico, and in old lake beds near Clovis, New Mexico. Much time, how¬ever, of each year has also been spent in studying the material collected, and in becoming familiar with the publications relating to the problem of the earlier peoples of America. The writer, therefore, wishes to acknowledge the opportunities thus afforded to him by the Trustees and Director of the University Museum and of the Academy of Natural Sciences of Philadelphia to carry on this research work.

Dr. Frederick Ehrenfeld, Professor of Geology at the University of Pennsylvania, is responsible for the original impetus that has resulted in this paper and I am, therefore, personally indebted to him for encouragement and for his scientific counsel. I also gratefully acknowledge the inspiration I have received from Dr. John C. Merriam, and his kindly interest in my work. Through him the Carnegie Institution of Washington has made it possible for me to visit most of the important sites where discoveries of supposedly early date have been made in North America in recent years—an opportunity much appreciated.

I should also like to acknowledge my personal obligations to Dr. J. Alden Mason, Curator of the American Section of the University Museum, for many helpful suggestions; to Dr. A. V. Kidder for valuable information supplied from time to time, and for his generous cooperation; to Dr. Malcolm Thorpe of Yale University for identification of vertebrate palaeontological material; to Dr. Alexander Wetmore of the United States National Museum for identification of bird bones from the cave; to Dr. R. W. Chaney of the University of California for identification of the wood and charcoal recovered; to Dr. Kenneth E. Lohman of the United States Geological Survey for identification of the diatoms from lake deposits; to Dr. Paul B. Sears of the University of Oklahoma for pollen analyses; to Mr. A. W. Postel of the Geological Department of the University of Pennsylvania for sand analyses; and to Dr. Henry A. Pilsbry of the Academy of Natural Sciences of Philadelphia for identification of the invertebrates. Also I am much indebted to Dr. Barnum Brown for his cooperation in visiting Burnet Cave, herein described, and for his help and suggestions in studying the palaeontological material.

I must also make grateful acknowledgment to many good friends in New Mexico: to Mr. Jesse L. Nusbaum for aid in securing necessary permits to work in some of the regions described; to Mr. R. M. Burnet first for originally indicating the cave herein described and later named after him, and secondly for his wholehearted interest and work in recovering the material collected; to Mr. A. W. Anderson and Mr. George Roberts for their generous help at Clovis, and to many others who have contributed in various ways to make my investigations easier. The pleasantest part of all such work is in the many good friends one makes, whose interest in furthering the progress of such an investigation is sincerely appreciated.

E. B. H.