Description of T. s. parietalis

From most of the vast area occupied by parietalis, material has not been available to us, and our concept of this subspecies is based chiefly on specimens and living material from Kansas and northeastern Colorado. A total of 520 live parietalis has been examined from the University of Kansas Natural History Reservation some 130 miles south and a little east of the type locality in Nebraska. These probably differ but little from typical specimens. The range of individual variation in pattern is especially notable. In those from the Reservation, the ground color varies from dull olive-brown to almost jet black. The markings on the dorsolateral area vary in color, in shade and in extent. These marks are chiefly confined to the skin between the scales of rows three to nine. Although most typically these marks are of some shade of red (hence the name "red-sided garter snake"), they may be pale buff, or pale greenish yellow, or may even have a bluish tint. In approximately ten per cent of the specimens from the Reservation there is no red at all in the pattern, which hence is similar to that of T. s. sirtalis in the eastern United States. Only a minority have all the dorsolateral marks red, and in some of these specimens the marks higher on the sides are progressively paler red, having a bleached out appearance. Most typically the marks between rows three to six are some shade of red while the smaller marks between rows six to nine are pale—yellowish, greenish, or buffy. In some the pale area of the lateral stripe is in varying degrees suffused with red, which may extend onto the edges of the ventrals and even to the underside of the tail.

T. s. parietalis may be diagnosed, on the basis of these snakes from northeastern Kansas, as follows: Size medium large (length 23.5 to 34.5, or, exceptionally 43.5 inches in adult males; 32.5 to 46.0 inches in adult females), dorsolateral color olive to black. Approximately every other scale of the third row is bordered above and anteriorly by a crescent-shaped area of scarlet colored skin. Similar crescent-shaped areas border the scales of the fourth and fifth rows and often two adjacent crescents meet at the ends of an intervening scale and fuse forming an H-shaped mark. Placed alternately with these markings are similar but smaller crescent-shaped markings on the skin of the upper half of the dorsolateral area on each side bordering every other scale of the sixth, seventh and eighth rows. The crescents of this upper series also may fuse to form series of H-shaped markings alternating with those of the lower series. The dorsal stripe is yellow with a faint dusky suffusion; it involves all of the middorsal scale row and approximately the adjacent half of the row on either side. The lateral stripe is faint, yellowish gray, chiefly on the upper half of the second scale row, lower half of third, and the intervening skin, and is often invaded or suffused by the red marks of the dorsolateral area. The first scale row, adjacent corners of the ventrals, and lower half of the second scale row are suffused with dark pigment and appear dusky, but this area is often marked with black, setting off the paler area of the lateral stripe. The ventrals are dull, whitish, faintly suffused with yellowish, greenish or bluish, each ventral having a black dot usually of semicircular shape on its anterior margin near the anterolateral corner.