_Coloration._--Grey, brown, or reddish above with two alternating series of dark brown or black spots on the back, or with a black zigzag dorsal band (Plate III., second figure), rarely with a single series of black vertebral spots; a lateral series of black spots, usually ocellar, with yellow centres; upper surface of head with dark symmetrical markings; a more or less distinct dark band on the temple, and another on each side of the nape, often edged with yellow in front; upper lip yellow, with dark bars on the sutures between the shields, or dark with a yellow spot on each shield. Lower parts yellow or red, checkered with black, or entirely black; the black of the belly may be connected with the ocellar lateral spots by black vertical bars. Iris golden, often mixed with brown. A specimen from Ponte Carrega, near Genoa, preserved in the Genoa Museum, is remarkable as being of a dark olive-grey, with three series of black and yellow ocellar spots. It is further exceptional in having the scales in nineteen rows. A second specimen, from the same locality, with the normal number of scales, has some of the vertebral spots ocellar. Specimens with ocellar vertebral spots are found also in Sardinia and in Spain. As in _T. natrix_, there occur, in the South of France, in Sardinia, in the Spanish Peninsula, and in North Africa, specimens with two light yellow or reddish lines along the back (Plate III., third figure), in addition to the usual markings (_C. aurolineatus_, Gervais, _T. chersoides_, Duméril and Bibron). Melanism is rare in this species, only one specimen being known, from Nantes in Southern Brittany; uniform black, with the exception of a few white spots on the belly. A remarkable variety (var. _incertus_, Fatio), connecting this species with the preceding, occurs in Switzerland near Geneva. Not only is its coloration sometimes very similar to that of _T. tessellatus_, but it agrees with it in the scales being often disposed in nineteen rows instead of twenty-one, and in the presence of eight upper labials, fourth or third and fourth entering the eye; however, the frequent presence of ocellar spots on the sides, and the low number of ventral shields (147 to 151), show that it should be referred to _T. viperinus_. _Size._--Rarely reaches a length of 3 feet in Europe, the largest specimens being from Sardinia. An Algerian specimen 3 feet 3 inches long is on record. _Distribution._--France as far north as Southern Brittany, the Forest of Fontainebleau, and the Department Aube, the whole of the Spanish Peninsula and the Balearic Islands, Southern Switzerland, north and south of the Alps, Liguria, Piedmont, Corsica, Sardinia, and Sicily. In Africa in Morocco, Algeria, and Tunisia, penetrating into the northern parts of the Sahara. In Liguria, Piedmont, and Ticino, _T. viperinus_ occurs alongside with _T. tessellatus_. It reaches an altitude of nearly 4,000 feet in the Alps.