Like most widely ranging subspecies, _parietalis_ and _fitchi_ vary geographically and local populations often are noticeably different from typical material. It is possible that future revisors will recognize additional subspecies, but in the variant populations known to us the degree of differentiation is slight as compared, for instance, with that in the subspecies of _Thamnophis elegans_. Scalation is remarkably uniform in all the subspecies of _sirtalis_, but coastal and northern populations tend to have fewer ventrals and subcaudals than do their counterparts farther inland and farther south. In their geographic variation the ventrals and subcaudals follow clines, and do not in themselves warrant subspecific divisions. Variation occurs chiefly in the color and pattern including the intensity of dark pigmentation of the dorsolateral area, head, ventral surface and lower edge of the lateral stripe; in extent, position and shade of red or pale colored markings on the dorsolateral area; in presence and extent of reddish suffusion on the head, in the region of the lateral stripe, and on the ventral surface of the tail. Most of these same characters vary within the subspecies _fitchi_, but the range of variation is relatively minor. Fitch (_op. cit._:582-584) described typical populations and also described briefly several small series from British Columbia, Idaho, Oregon, and California which were not entirely typical. Most frequent variation was in heavy reddish suffusion on the sides of the head not found in typical _fitchi_. In each local population of this subspecies the characters seem to be remarkably uniform and stable. * * * * * Illustration: FIG. 2. Diagrammatic drawing of pattern in stretched skin of _T. s. fitchi_; the pale markings on the black dorsolateral area are scarlet (x 2-1/2). * * * * * Illustration: FIG. 3. Diagrammatic drawing of stretched skin of _T. s. parietalis_; the scarlet markings extend farther dorsally than in _T. s. fitchi_ and black spots are prominent on the ventrals laterally. Some individuals of _parietalis_ have much paler ground color, resembling _ornata_ except in minor details (x 2-1/2). * * * * * Illustration: FIG. 4. Diagrammatic drawing of stretched skin of _T. s. ornata_. The ground color is like that of _parietalis_ but paler with a continuous black area bordering the dorsal stripe (x 2-1/2). * * * * *