Illustration: FIG. 1. Map of a part of the United States in the region of the Great Plains and Rocky Mountains, and adjacent northwestern Mexico showing supposed range (shaded) and localities of authenticated occurrence (dots) of _Thamnophis sirtalis_. 1. _T. s. fitchi_, 2. _T. s. parietalis_, 3. _T. s. annectens_, 4. _T. s. ornata_. Records from Idaho and Wyoming are based on specimens in the University of Kansas Museum of Natural History collection. Other records are based on Woodbury (1931) for Utah, Hudson (1942) for Nebraska, Maslin (1959) for Colorado, Smith (1956) for Kansas, R. G. Webb (MS) for Oklahoma, Brown (1950) and Fouquette and Lindsay (1955) for Texas, Cope (1900), Van Denburgh (1924), Little and Keller (1937) for New Mexico, and Smith and Taylor (1945) for Mexico. * * * * * Smith (1956:292) recorded _parietalis_ from three outlying stations in the western quarter of Kansas, from Wallace, Hamilton and Meade counties in the drainages of the Smoky Hill River, Arkansas River, and Cimarron River, respectively. Permanent springs in Meade County State Park perhaps account for the survival of an isolated colony there. Several specimens from that locality seen by Fitch in August, 1960, when recently collected by a University of Michigan field party, seemed to be of the Texas subspecies _annectens_, as their dorsal stripes were reddish orange, and markings on the dorsolateral area were pale yellow rather than red. Specimens from the Texas Panhandle, from Hemphill County (Brown, 1950:207) and nine miles east of Stinnet, Hutchison County (Fouquette and Lindsay, 1955:417) likewise are most nearly like _annectens_ judging from the authors' descriptions. The specimens from nine miles east of Stinnet averaged large; the two largest would have attained or slightly exceeded four feet in length if they had had complete tails. No _sirtalis_ so long as four feet has been recorded elsewhere. Records are lacking from the drainages of the Republican, North Canadian, Brazos and Colorado River drainages in the High Plains, but possibly isolated populations occur in some of these also. The only record from the Pecos River drainage is that of Bundy (1951:314) from Wade's Swamp near Artesia, Eddy County, New Mexico. This locality is separated by some 140 miles from any other known station of occurrence.