So far as trustworthy records are concerned, the largest snakes known, the Malay _Python reticulatus_ and the South American Anaconda, _Eunectes murinus_, reach a length of 25 to 30 feet. Measurements of skins must be accepted with caution, as a skin may easily be stretched to once and a half its real length; in estimating the exact length from such a stretched skin, it is necessary to deduct the interstitial spaces showing between the scales, and about one-fourth of the scale to allow for the overlap. The smallest snake known is 4 inches long (_Glauconia dissimilis_). The largest European snake (_Coluber quatuorlineatus_) is reported to reach a length of 8 feet; the smallest (_Typhlops vermicularis_) does not exceed 14 inches. KEY TO THE IDENTIFICATION OF THE EUROPEAN SNAKES FROM EXTERNAL CHARACTERS ONLY I. Eyes minute, under the head-shields; mouth small, inferior; body vermiform, covered with uniform scales above and beneath; vent close to the end of the body, the extremely short tail ending in a small spine _Typhlops vermicularis._ II. Eyes very small, with vertical pupil; upper surface of head covered with small scales; ventral shields much narrower than the body; tail short, ending obtusely; subcaudals single, or mostly single; scales smooth or feebly keeled, in 40 to 50 rows _Eryx jaculus._ III. Eyes small, moderate, or large; ventral shields at least nearly as broad as the body; tail tapering to a point; subcaudals paired. _A._ Pupil round; upper surface of head with nine large shields; no upper labial in contact with the parietal; anal shield usually divided. 1. Dorsal scales strongly keeled, with paired apical pits; a single anterior temporal. _a._ Nostrils lateral; internasals broadly truncate in front. Scales in 19 rows; normally 1 pre- and 3 postoculars; usually 7 upper labials, third and fourth entering the eye; ventrals 157-181; subcaudals 50-88 _Tropidonotus natrix._ _b._ Nostrils directed upwards; internasals much narrowed in front. Scales in 19 rows; normally 2 pre- and 3 or 4 postoculars; suboculars sometimes present; usually 8 upper labials, fourth or fourth and fifth entering the eye; ventrals 160-187; subcaudals 48-79 _Tropidonotus tessellatus._ Scales in 21 (rarely 19 or 23) rows; normally 1 or 2 pre- and 2 postoculars; usually 7 upper labials, third and fourth entering the eye; ventrals 147-164; subcaudals 46-72 _Tropidonotus viperinus._ 2. Dorsal scales smooth or feebly keeled; normally a single loreal. _a._ Two or three superposed anterior temporals (very rarely one); nostril usually between two nasals.