Maxillary teeth increasing in size posteriorly, the two last often separated from the others by a narrow interspace. Head elongate, distinct from neck; eye rather large, with round pupil. One or more subocular shields. Body much elongate; scales smooth, with apical pits. Tail long. The species of this genus, about thirty in number, are distributed over Europe, North Africa, Asia, and North and Central America. Three inhabit Europe. 6. ZAMENIS GEMONENSIS, Laurenti (_Coluber viridiflavus_, Lacepède; _C. atrovirens_, Shaw) The European Whip-Snake _Form._--Slender; snout rounded, with distinct canthus, moderately prominent, concave on each side in front of the eye. Tail three and one-third to four and one-third times in the total length. _PLATE IV_ [Illustration: ZAMENIS GEMONENSIS _Young, after Sordelli_] [Illustration: Z. GEMONENSIS, VAR. PERSICUS _After Sordelli_] [Illustration: Z. GEMONENSIS, VAR. VIRIDIFLAVUS] _Head-Shields._--Rostral a little broader than deep, the portion visible from above measuring one-fourth to two-fifths its distance from the frontal. Frontal more or less bell-shaped, not or but little broader than the supraocular, once and two-thirds to twice as long as broad, as long as or a little longer than its distance from the end of the snout, a little shorter than the parietals. Loreal as long as deep or longer. One preocular (rarely two), extending to the upper surface of the head, but never in contact with the frontal; a small subocular below the preocular; two postoculars (rarely three). Temporals 2 + 2 or 2 + 3 (rarely 1 + 2). Upper labials eight, fourth and fifth entering the eye, fifth and seventh deepest. Five lower labials (rarely four) in contact with the anterior chin-shields, which are usually shorter than the posterior. [Illustration: FIG. 19 (after Sordelli)] _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.