For assistance in the field, we are especially grateful to the students who were enrolled in the Field Course in Vertebrate Zoology at The University of Kansas in the summers of 1961, 1965, and 1970, and to M. A. Levy, R. R. Patterson, and T. H. Swearingen. In 1965 and 1970, the summer field course was supported in part by grants (GE-7739 and GZ-1512, respectively) from the National Science Foundation; Andersen was supported in the field in 1968 by a grant from the Kansas City Council for Higher Education. Personnel of the U.S. Forest Service (Sioux Division, Custer National Forest), particularly District Ranger Timothy S. Burns, were most helpful to us in the field, as were Wardens Wesley Broer and Merritt Paukarbek of the South Dakota Department of Game, Fish and Parks. Robert Kriege, Federal predator control agent stationed in Buffalo, was most generous in sharing with us his knowledge of rodents and carnivores in the area, and many present or former residents, particularly Carl Cornell and Spike Jorgensen, also provided useful information and were helpful in other ways. Ectoparasites reported here were identified by Cluff E. Hopla (fleas), Richard B. Loomis (chiggers), and Glen M. Kohls (ticks). Other than mammals housed in the Museum of Natural History, we examined only three, two in the U.S. National Museum (USNM) and one in the collection at South Dakota State University, Brookings (SDSU). LITERATURE CITED ANONYMOUS 1959. Building an empire: a historical booklet on Harding County, South Dakota. Buffalo Times-Herald, 108 pp. BAILEY, V. 1915. Revision of the pocket gophers of the genus Thomomys. N. Amer. Fauna, 39:1-136. 1927. A biological survey of North Dakota. N. Amer. Fauna, 49: vi + 1-226 [this publication is dated 1926, but actually was published on January 8, 1927]. BAKER, C. L. 1952. Geology of Harding County. Rept. South Dakota State Geol. Surv., 68:1-36 (mimeographed). BROWN, L. N. 1963. Maturational molts and seasonal molts in Peromyscus boylii. Amer. Midland Nat., 70:466-469. COLLINS, H. H. 1918. Studies of normal moult and of artificially induced regeneration of pelage in Peromyscus. Jour. Exp. Zool., 27:73-99. GOLDMAN, E. A. 1944. Classification of wolves. Pp. 387-507, _in_ The wolves of North America (S. P. Young and E. A. Goldman), Amer. Wildlife Inst., Washington, D.C., xx + 636 pp. HALL, E. R., and K. R. KELSON 1959. The mammals of North America. Ronald Press, New York, 2: xxx + 1-546 + 79 and 2: viii + 547-1083 + 79. HENDERSON, F. R., P. F. SPRINGER, and R. ADRIAN 1969. The black-footed ferret in South Dakota. South Dakota Dept. Game, Fish and Parks, Pierre, 37 pp. HOFFMANN, R. S., and J. K. JONES, JR.