In the course of my field study many workers on the University of Kansas Natural History Reservation helped by capturing skinks; especially Sydney Anderson, Richard Freiburg, John Hawken, Dennis G. Rainey and Lewis L. Sandidge. Mr. Robert Gordon very kindly furnished information on specimens in the Tulane University collection, which served as a basis for comparing the breeding schedule of the southern population with that of _E. fasciatus_ in northeastern Kansas. Dr. W. J. Breckenridge kindly permitted examination of material in the University of Minnesota Museum of Natural History. Dr. Edward H. Taylor has made helpful suggestions from time to time. Mr. Richard B. Loomis helped me in various ways with the field work, and made available his personal field notes with records of predation on _Eumeces_ by various snakes. Dr. E. Raymond Hall, Director of the Museum of Natural History, has critically examined the manuscript, and has been helpful in various ways. The line drawings and graphs, with the exception of Figures 8 and 9, were made or completed by Mrs. Louise Brunk, artist for the Museum. The study here reported on was initiated in May 1949, and was continued through 1950, 1951 and 1952. A few observations made in 1948 have been included. Various separate items of information obtained in 1953 have likewise been incorporated especially where histories of individual skinks are presented, but the manuscript was completed in essentially its present form in the fall of 1952. Methods