_Coloration._--In the typical _Z. gemonensis_ the upper parts are yellowish-brown or pale olive, anteriorly with blackish cross-bars or numerous small black spots, the black scales with a yellowish shaft, the lower parts yellowish-white or pale yellow, rarely more orange; the sides of the head are yellow, the shields edged with blackish. A female, 3-1/4 feet long, from Levico, Trentino, preserved in the Genoa Museum, is uniform reddish-brown above, with mere traces of darker markings on the head and nape. There is every gradation between this form and the var. _viridiflavus_ or _atrovirens_ (Plate IV., third figure), which is dark green or black above, with yellow spots forming transverse series or bars on the anterior part of the body, and longitudinal streaks, following the series of scales, on the posterior part and on the tail; the yellow sometimes predominates over the black, or may appear as a shaft along each dark scale; the preocular and postocular shields are yellow, the labials likewise yellow, with black spots or bars. The lower parts are yellow or greenish-white, with or without black dots, and usually with a series of large black spots on each side. Some specimens of both the typical form and the var. _viridiflavus_ are entirely black or nearly black. (_Z. carbonarius_, Bonaparte; _Z. sardus_, Suckow). In some localities and islands only black specimens occur. In the var. _caspius_, Iwan (_trabalis_, Pallas, Plate V., first figure; _persicus_, Jan, Plate IV., second figure), from Hungary, Bosnia, Herzegovina, Corfu, Bulgaria, Roumania, Greece, Turkey, Southern Russia, Northern Asia Minor, and North-West Persia, the upper parts are pale olive or reddish-brown, with or without brown or black spots, and each scale bears a yellowish or pale brown longitudinal streak; there is often a dark longitudinal streak on the nape; the belly is uniform orange or red. Another variety, var. _asianus_, Boettger, from Asia Minor, Rhodes, Cyprus, and Syria, has the upper parts brown or olive, each scale with a longitudinal light streak, and there are usually large black spots relieved by yellowish shafts; the belly is red, spotted or dotted with black. Melanism is frequent in this form, such specimens being entirely black except on the chin and throat, which are yellow variegated with red.