For hibernation, hollow trees, fissures in rocks, holes in the ground or in railway embankments, are selected, and numerous individuals sometimes congregate in the same retreat. In the mild winters of the South of Europe they remain quiet, without being torpid, and resume activity very early in the spring.
In the Alemtejo, according to Gadow, when during the rainless and hot summer the small rivers have nearly dried up, these snakes collect in great quantities in the remaining stagnant and muddy pools, and, as the stock of suitable fish gets exhausted, are often reduced to a deplorably emaciated condition. By the month of August they have become so thoroughly aquatic that they cannot be kept alive in dry surroundings for twenty-four hours, apparently dying from some kind of cutaneous suffocation. The same observer once caught a Viperine Snake in a ditch whilst it was swallowing an eel of nearly its own length.
Some specimens show so great a superficial resemblance to the Common Adder, Vipera berus, which, however, being a more northern reptile, very seldom occurs in the same localities—that this snake well deserves its name Viperinus. A celebrated herpetologist, Constant Duméril, was once himself deceived by this resemblance and bitten by a Vipera berus which he had picked up in the Forest of Senart, near Paris, believing it to be a Tropidonotus viperinus; whilst, conversely, a specimen of the harmless snake was killed in mistake for a Viper by no less an expert than Dr. Viaud-Grandmarais.
Breeding.—This snake pairs in March and April, and sometimes again in the autumn; but the eggs are only laid at one season, in June or July, and hatch in August, September, or October. The eggs, numbering four to twenty, are deposited in holes not far from water, often in abandoned galleries of voles or moles. The young at birth measure 4 to 61⁄2 inches, and soon resort to the water, where, unlike those of the Grass-snake, they are frequently met with.
Genus ZAMENIS, Wagler
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.