Forty-five specimens in the University of Colorado Museum from northwestern Colorado were subjected to pattern analysis. In three specimens the dorsolateral black area between the dorsal stripe and the lateral stripe on each side has no markings, and in eight others there is only an occasional fleck or crescent on the skin between the sixth and seventh scale rows. All others have the normal complement of dorsolateral crescents or flecks between the scales of rows three and four, four and five, and five and six. But, these specimens vary in extent of development of the crescents in the upper half of the dorsolateral area on each side--between scale rows six and seven, seven and eight, and eight and nine. Only six snakes show traces of the crescents of the uppermost series (between scale rows eight and nine). Development of these crescents is variable but in all the specimens the crescents are confined to the anterior half of the body. The crescents between rows six and seven and between seven and eight are present in 20 specimens and in ten of these the crescents are conspicuous and regularly arranged, often meeting and consequently form H-shaped markings. In most of the snakes the crescents are best developed in the second fifth of the body and disappear posteriorly. In five of the twenty, crescents between rows six and seven are fairly regular, but those between rows seven and eight are few and appear only sporadically. In eight specimens there are no crescents between either rows seven and eight or eight and nine. In eight others the crescents between rows six and seven are likewise absent, and only the crescents between rows three to six are present. These specimens from Colorado also differ from typical _parietalis_ in having the black spots on the anterolateral edges of the ventrals less developed. In three of the 45 these spots are lacking entirely and in four others they are few and small. In the majority of specimens the spots are from 1/4 to 1/5 the length of the ventrals. In approximately one-third of the specimens the spots are absent posterior to mid-body. In five specimens obtained at Sheridan Lake, Pennington County, South Dakota, in the Black Hills in August, 1960, dorsolateral areas are dark with red crescents small and inconspicuous, and with black spots either lacking from the ventrals or only faintly developed. In two specimens from Sundance, Crook County, northeastern Wyoming, the red crescents are small and inconspicuous also. In one of these specimens, KU 28028, small black spots are present in the corners of the ventrals, but in the other, KU 23654, the spots are absent.