In having the dorsolateral area consistently black, with the three uppermost series of red crescents reduced or absent, and in having the ventral black spots reduced or absent, these specimens from Colorado, Wyoming, and South Dakota differ from more eastern and more typical _parietalis_, and tend toward _fitchi_, even more strongly than some Idaho specimens tend toward _parietalis_. Nevertheless, all things considered, the Continental Divide is the most logical boundary between the two subspecies, even though occasional individuals and even local populations deviate from the general trend of characters from east to west. ACKNOWLEDGMENTS Dr. Doris M. Cochran of the United States National Museum kindly furnished information concerning the type specimen of _Eutainia dorsalis_ formerly in the National Museum collection but now lost. Dr. James S. Findley of the University of New Mexico and Dr. Ralph J. Raitt of New Mexico State University contributed habitat notes and records of specimens and loaned us critical specimens of _T. sirtalis_ from New Mexico. Drs. George F. Baxter of the University of Wyoming, John M. Legler of the University of Utah, and Wilmer W. Tanner of Brigham Young University kindly provided us with information concerning the specimens in the collections of their respective institutions, and their personal observations concerning the distribution of garter snakes in their states. Alice V. Fitch, Chester W. Fitch and Donald S. Fitch assisted in the collection of fresh specimens in Oregon and Utah and the unsuccessful search of many a mosquito-infested meadow in southern Wyoming and northwestern Colorado in July, 1959. Dr. R. G. Webb made available his MS on reptiles of Oklahoma. This taxonomic study of garter snakes originated as a by-product of the senior author's study of ecology and economic bearing of snakes in the central Plains Region of the United States, for which support received from the National Science Foundation is gratefully acknowledged. LITERATURE CITED BAIRD, S. F. 1859. Reptiles of the boundary. United States and Mexican Bound. Surv., 2, 1-35, 41 pls. BAIRD, S. F., and GIRARD, C. 1853. Catalogue of North American reptiles in the Museum of the Smithsonian Institution. Smithson. Miscl. Col., part 1, Serpents., pp. xvi + 172. BROWN, B. C. 1950. An annotated check list of the reptiles and amphibians of Texas. Baylor Univ. Studies, pp. xii + 259. BUNDY, R. E. 1951. New locality records of reptiles in New Mexico. Copeia, 1951 (4):314. COCKERELL, T. D. A. 1910. Zoology of Colorado. Univ. of Colorado, Boulder, vii + 262 pp. CONANT, R. 1958. A field guide to the reptiles and amphibians of the United States and Canada east of the 100th Meridian. Houghton Mifflin Co., Boston, xviii + 366 pp. COPE, E. D.