Light and fire attract it. It does not climb trees, but is frequently found coiled up on boughs of dead wood scattered on the ground. When on the defensive, and preparing to bite, it throws its head back, and makes a sudden dart of from a foot to sixteen inches. If irritated it makes a sort of hissing noise. To pass the winter it retires into the crevices of rocks or into old tree-trunks, where it entwines itself closely with a number of its congeners. In this way ten or fifteen vipers are frequently found together in the same hole. In April, the whole company awakes, and copulation then takes place. The eggs are laid in August and September, and the young immediately crawl out of the shell, already prepared to bite, and capable of finding their own food. Their length at birth amounts to 230 millimetres. The two glands of an adult adder contain about 10 centigrammes of poison. This small quantity is sometimes sufficient to cause death; out of 610 persons bitten, Rollinger returns 59 deaths, or about 10 per cent. In the departments of Vendée and Loire-Inférieure alone, Viaud Grand Marais has noted during a period of six years 321 cases of bites from adders, 62 of which were followed by death. In Auvergne, Dr. Fredet[2] (of Royat) returns 14 cases, which caused 6 deaths. Vipera aspis (_Asp_, or _Red Viper_). (Fig. 21, _2_, and fig. 22.) Snout slightly turned up, soft and squarely truncate; vertical diameter of the eyes equal to the space separating them from the mouth; upper surface of the head usually covered with small, imbricate, smooth or feebly keeled scales, in 4-7 series, between the supraocular shields, which are prominent. The frontal and parietal shields are usually wanting; sometimes they are distinct, but small and irregular; the former are separated from the supraoculars by two series of scales; 8-13 scales round the eyes; two (rarely three) series of scales between the eyes and the labials; nasal shield single, separated from the rostral by a naso-rostral shield. Body scales in 21-23 rows, strongly keeled; 134-158 ventrals; 32-49 subcaudals. Coloration very variable, grey, yellowish, brown, or red above, with a zigzag band as in _V. berus_. Usually a black =U=-shaped mark on the hinder part of the head, with a longitudinal black streak behind the eyes; upper lip white, or yellowish. Ventral surface yellow, white, grey, or black, with lighter or darker markings. Total length, 620-675 millimetres; tail 75-95. _Habitat_: France (especially Vendée, the Forest of Fontainebleau, and the South), Pyrenees, Alsace-Lorraine, the Black Forest, Switzerland, Italy and Sicily, and the Tyrol.