Scales with two apical pits, in nineteen (rarely seventeen or twenty-one) rows. Ventral shields more or less distinctly angulate laterally, 160 to 230 (usually under 200 in the typical form and the var. caspius, 190 or more in the vars. viridiflavus and asianus); anal divided; subcaudals 87 to 131.
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, 31⁄4 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.
The very young of the typical form, as well as that of the var. viridiflavus, has a striking livery ([Plate IV]., first figure), the head and nape black with yellow markings, or olive with black-edged yellow markings, contrasting sharply with the pale olive-grey of the body; the most conspicuous and constant of the yellow markings consist of a bar between the eyes, interrupted on the frontal shield, but sometimes continuous with the yellow of the postoculars, five or six small round spots on the parietal shields, and a V- or W-shaped line just behind the parietals, followed by one or two others separating the dark cross-bars which may be present on the nape, and occasionally even continue some way down the anterior part of the body. This livery persists in some half-grown specimens.
In young individuals from Syria (var. asianus) the head is not differently coloured from the olive-brown body, and the markings described above appear as mere traces; on the other hand, the whole body has black and yellow spots or cross-bars above, and the belly is profusely marked with round black spots.
In the new-born of the var. caspius, of which I have examined only one specimen, 11 inches long, from the Crimea, the head is olive-brown like the body, which bears dark brown spots and narrow cross-bars; and there is a dark brown streak along the middle of the nape, as is sometimes the case in the typical form. The belly is unspotted. A young from Malta is intermediate in its markings between the typical form and this variety.
The young of the so-called black variety are not black at birth, but similar to the normal young of the races to which they belong.
The four principal forms—viridiflavus, gemonensis, caspius, and asianus—are so completely connected that I cannot regard them as more than geographical races or varieties.