GENUS COLUBER, LINNÆUS Maxillary teeth equal or nearly equal in length. Head elongate, distinct from neck; eye moderately large, with round pupil. Body more or less elongate; scales smooth or feebly keeled, with apical pits. Tail moderate or long. This large genus, embracing close upon fifty species, is represented in Europe, Asia, and North and tropical America. Five species in Europe. Very nearly allied to _Zamenis_, but distinguished principally by the posterior teeth of the upper jaw not being at all enlarged, and, further, in being, like _Coronella_, constrictors. 9. COLUBER QUATUORLINEATUS, Lacepède (_Elaphis cervone_, Aldrovandi; _Coluber quatuorradiatus_, Gmelin) Aldrovandi's Snake _Form._--Moderately slender. Snout obtuse, scarcely prominent. Tail one-sixth to one-fourth of the total length. [Illustration: FIG. 22 (after Sordelli)] _Head-Shields._--Rostral broader than deep, just visible from above. Frontal once and one-fourth to once and a half as long as broad, as long as its distance from the rostral, shorter than the parietals. Loreal nearly as long as deep, with one or two small shields below it. One preocular, rarely divided, with a subocular below it; two or three postoculars. Temporals 2 + 3 or 3 + 4. Upper labials eight (exceptionally nine), fourth and fifth (or fifth and sixth) entering the eye. Four or five (rarely three) lower labials in contact with the anterior chin-shields, which are longer than the posterior. _PLATE VI_ [Illustration: COLUBER QUATUORLINEATUS _Young, after Sordelli_] [Illustration: COLUBER QUATUORLINEATUS _After Werner_] [Illustration: COLUBER QUATUORLINEATUS, VAR. SAUROMATES _After Sordelli_] [Illustration: COLUBER DIONE _After Sordelli_] _Scales_ feebly but distinctly keeled, except on the outer rows, with two apical pits, in twenty-five (rarely twenty-three or twenty-seven) rows. Ventral shields not or but very obtusely angulate laterally, 195 to 234; anal divided; subcaudals 56 to 90.