This species may be divided into several geographical forms. The typical form will be described first.

Form.—Short and heavy. Snout pointed, produced into an erect, horn-like dermal appendage covered with scales; canthus rostralis strong, sometimes slightly raised, loreal region slanting more or less towards the lip. Vertical diameter of the eye less than its distance from the mouth in the adult. Length of tail six to nine and a half times in the total length in males, eight to eleven times in females.

Head-Shields.—Rostral usually broader than deep. Naso-rostral (rarely divided into two) usually reaching the canthus rostralis, and extending considerably higher up than the upper border of the rostral. Rostral appendage covered with ten to seventeen scales, arranged in three (rarely two or four) transverse series between the rostral shield and the apex. Upper surface of head covered with small smooth or faintly keeled, subimbricate scales, among which a feebly enlarged frontal shield or a frontal and a pair of parietals are rarely distinguishable; when present, the frontal is separated from the supraocular by two series of scales; on the vertex five to eight series of scales separate the supraoculars. Two (rarely three) canthal scales, the second separated from the supraocular by the upper preocular. Supraocular with very convex outer border, usually not extending posteriorly beyond the vertical of the eye. Ten to thirteen scales round the eye; one or two vertical series of scales separate the preoculars from the nasal, which is single or rarely divided, and hollowed out. Two series of scales between the eye and the labials. Upper labials eight to twelve, usually nine or ten, usually fourth and fifth below the eye. Temporal scales smooth or feebly keeled. Four or five lower labials in contact with the single pair of chin-shields.

Scales in twenty-one or twenty-three (rarely twenty-five) rows, with two apical pits, strongly keeled, those of the outer row smooth or feebly keeled. Ventral shields 143 to 161 in males, 147 to 160 in females; anal entire; subcaudals 27 to 40 in males, 24 to 37 in females.

Coloration.—Grey, pinkish-grey, brown, yellowish-brown, or brick red above, with a more or less distinct wavy or zigzag black or brown, usually black-edged, band along the back, or a series of large rhombs connected on the median line, with or without a lateral series of dark spots; specimens with the markings of an intense black are males (Plate XIV.). Head with or without dark markings, very variable in disposition, sometimes forming a Λ on the occiput, or a lyre-shaped figure confluent with the dorsal band; a dark streak or broad band from the eye to the angle of the mouth, sometimes continued along the neck; dark vertical bars often present on the sides of the snout and under the eye; on the lower lip, the dark shade, if present, broken up by light bars separated by two to four labial shields. Belly greyish or pink, powdered with brown or black, or dark bluish-grey, with or without black and white spots; lower surface of end of tail orange or coral red, rarely yellow. Iris golden. Specimens with a straight brown vertebral band flanked with triangular black spots pointing outwards (var. steindachneri, Werner) are known from Hungary, and resemble certain colour varieties of V. berus and V. aspis. Black specimens are very rare.

The following varieties are important geographical forms occurring in Europe:

Var. montandoni, Boulenger: Naso-rostral shield never reaching the canthus rostralis nor the summit of the rostral shield, which is deeper than broad (once and one-seventh to once and a half); rostral appendage clad with ten to fourteen scales, in three (rarely two or four) transverse series between the rostral shield and the apex. Scales in twenty-one rows. Ventral shields 149 to 158; subcaudals 30 to 38. A more or less distinct dark blotch on the lower lip, involving five to seven labial shields without complete interruption. Lower surface of end of tail yellow.

Var. meridionalis, Boulenger: Naso-rostral shield never reaching the canthus rostralis, and but rarely extending higher up than the upper border of the rostral, which is often as deep as broad or a little deeper than broad; rostral appendage clad with fourteen to twenty scales, in four or five (rarely three) transverse series between the rostral shield and the apex. Supraciliary edge usually more prominent than in the typical form, sometimes slightly angular. Scales in twenty-one rows (very rarely twenty-three). Ventral shields 133 to 147; subcaudals 24 to 35. A more or less distinct dark blotch on the lower lip, involving five or six labial shields without interruption. Lower surface of end of tail yellow.

Size.—This Viper exceptionally attains a length of 3 feet. The largest male in the British Museum measures 2 feet 6 inches, the largest female 2 feet 4 inches. In V. berus females grow to a larger size than males; in this species, as in V. aspis, the reverse appears to be the rule.

Hybrid.—A female specimen, presumed to be a hybrid between V. berus and V. ammodytes, was obtained by Captain Veith in 1902 in Carinthia, in a locality where both these species occur together. The shape of the head is exactly that of a typical V. aspis, the snout distinctly turned up at the end, but without wart or scaly appendage, the raised portion being covered by the apex of the rostral shield and three apical shields. The rostral shield, which is a little deeper than broad (5 : 4), extends above the level of the slightly raised canthus rostralis, which bears two shields, the second in contact with the supraocular. The naso-rostral extends to the canthus rostralis, where it joins the first canthal and the lateral apical shield; one series of scales between the nasal shield and the preoculars. On the upper surface of the head the snout is covered with fifteen subimbricate smooth scales, in addition to the canthals and apicals. A frontal shield and a pair of parietals are well developed, although smaller than in an average V. berus; the parietals are in contact with the frontal, between which and the supraoculars two series of scales intervene. The supraocular, as in V. berus, extends backwards considerably beyond the vertical of the eye. Eleven scales round the eye; two series of scales between the eye and the labials. Temporal scales smooth. Upper labials nine, fourth and fifth below the eye. Scales in twenty-one rows, outer row smooth. Ventrals 159; subcaudals 31.

Grey-brown above, with a reddish-brown or mahogany-coloured zigzag vertebral band and a lateral series of paler reddish-brown spots; temporal band ill-defined in front; no markings on the upper surface of the head; lips pinkish, with a few reddish-brown spots. Ventral shields pale brownish, finely speckled or powdered with blackish, and with small whitish spots on the free edge and reddish brown spots on the sides. Tail orange red below. Iris fire red.

Total length 2 feet 21⁄3 inches; tail 22⁄3 inches.

Distribution.—The typical form is known from Northern Venetia, Austria-Hungary (Styria, Carinthia, Southern Tyrol, Carniola, Illyria, Istria, Croatia, Slavonia, and eastward through Southern Hungary to Transylvania), Dalmatia, Bosnia, Herzegovina, Montenegro, Albania, and Servia. In the Alps up to 1,300 feet, in the Balkan Peninsula up to 7,500 feet. The var. montandoni inhabits Roumania and Bulgaria. The var. meridionalis inhabits Greece, with the Archipelago, Asia Minor, and Syria.

The specimens from Transcaucasia constitute a further variety (var. transcaucasiana, Boulenger), agreeing with the var. montandoni in the rostral scutellation and in the number of ventral shields (150 to 156), but differing in the markings on the back; these consist of dark bars or alternating paired dark spots, as in the typical form of V. aspis. The dark and light markings on the lower lip are as in the typical V. ammodytes, and the lower surface of the tail is pale yellow or greenish towards the end.

Habits.—Notwithstanding its name ammodytes, this Viper is by no means restricted to sandy localities; on the contrary, it shows a predilection for dry stony hills with low vegetation, and has often been found climbing bushes. It avoids thick forest, but occurs on the edges of woods and in clearings, as well as on the borders of roads through woods. In the cooler regions of the mountains, which it ascends to a considerable altitude, it is essentially diurnal, leaving its retreat only when the sun shines; but in warm localities it is stated to be principally nocturnal, appearing in numbers by moonlight. The length of its period of hibernation depends entirely on the climate, but when the winter is mild it may be seen about in midwinter whenever the sun shines. The poison of this Viper is stated to be more active than that of V. berus and V. aspis, and, as the snake is very common in some parts of Austria and the Balkan Peninsula, fatal accidents to man are frequent.

The food consists of small mammals and birds, and also of lizards. V. ammodytes does much better in captivity than its European congeners, and takes food more readily.

The hissing is louder than in V. berus and V. aspis, and it is often produced, on the approach of man, by specimens lying in such perfect concealment that their presence would not otherwise be suspected; this habit, like the rattling of the Crotalus, is evidently detrimental to the species in its relation to man.

This species is extremely abundant in some parts of Austria, and over 7,000 specimens were killed in a district of Southern Styria in the course of two years (1892, 1893). According to Werner, it is the commonest of all snakes in Bosnia and Herzegovina.

Reproduction.—Pairing takes place in the spring, sooner or later according to altitudes, and the young, five to fourteen in number, are born in August.

Form.—Short and heavy. Snout rounded, obtuse, usually with well-marked canthus, and the loreal region slanting towards the mouth. Eye small, its vertical diameter less than its distance from the mouth in the adult. Nostril large and directed backwards. Length of tail six (males) to ten times (females) in the total length.

Head-Shields.—Rostral as deep as broad, a little broader than deep, or slightly deeper than broad, reaching or nearly reaching the upper surface of the snout, and in contact with two or three apical shields. Upper surface of head covered with small subimbricate scales, which are all more or less distinctly keeled, or, rarely, smooth on the snout and forehead; seven to twelve longitudinal series of scales between the eyes (supraoculars included); two to four canthal shields, of which the anterior is the largest, and may be regarded as a supranasal. Supraocular narrow, usually broken up into two or more small shields. Twelve to eighteen scales round the eye; two or three series of scales between the eye and the labials; two or three vertical series of scales separate the preoculars from the nasal, which is single and often strongly hollowed out, and usually partially fused with the naso-rostral. Upper labials nine to twelve, usually fourth and fifth below the eye. Temporal scales keeled. Four or five lower labials in contact with the single pair of chin-shields.

Scales in twenty-three to twenty-seven rows, usually twenty-five, with two apical pits, strongly keeled, those of the outer row smooth or feebly keeled. Ventral shields 151 to 177 in males, 153 to 180 in females; anal entire; subcaudals 42 to 51 in males, 38 to 49 in females.

Coloration.—Very variable. The typical form, which alone is represented in Europe, and was originally described from Cyprus, is grey, greyish-buff, or pale brown, above, with two dorsal series of darker spots, which may stand in pairs, alternate, or unite to form cross-bars, and a lateral series of large dark spots or bars. A more or less distinct dark band on each side of the head, passing through the eye and often extending to the neck; a dark bar or triangular spot below the eye, and usually another below the nostril. Lower parts pinkish-white, powdered with grey-brown, with or without dark brown spots; end of tail yellow. The ground colour of the young is pink or flesh-colour. In specimens from desert sandy regions in Asia and North Africa the markings may be very indistinct, the snake being of a nearly uniform pale buff.

In the var. mauritanica, Guichenot, from Morocco and Algeria, the back has three series of very large dark brown or reddish-brown spots, separated by a network of the yellowish ground colour, or the middle series may be transformed into a wavy or zigzag band. The scales in this variety are usually in twenty-seven rows, instead of twenty-five (rarely twenty-three) as in the typical form.

Size.—This species, the largest of European Vipers, grows to a length of 41⁄2 feet.

Distribution.—The European habitat of V. lebetina is restricted to the Cyclades, where it is not uncommon on the island of Tinos, and appears to be found also on Kimoli. It is common on Cyprus, where it is called Kufi, or Deaf Snake, and extends from Syria and Asia Minor through Transcaucasia, Mesopotamia, Persia, Northern Baluchistan, to Afghanistan and Cashmere. It is further found on the Atlas of Morocco and Algeria, near Oran and Bona, and in Tunisia. Its reported occurrence in Egypt has not been confirmed by recent investigations.

Habits.—According to M. Doumergue—who has had ample opportunities of observing this Viper near Oran, where it is common—it is a nocturnal reptile, rarely moving about in the daytime. It inhabits rocky localities, where there is brushwood, and vineyards. During the day it remains sluggish under large stones. It is most frequently met with in April and May.

On Milos, Dr. de Bedriaga observed this much-dreaded snake, the bite of which is probably as bad as that of its Indian ally, the Daboia, V. russelli, to occur frequently in gardens, and to crawl about near houses in villages after sunset. The same observer has noted a sort of valvular closing of the nostril through raising of the posterior part of the nasal shield when the snake prepares to strike.

The food consists principally of mammals up to the size of a rabbit.

Reproduction.—According to Doumergue’s observations in Algeria, the young, up to thirteen in number, are born in May and June.

Head distinct from neck, its upper surface covered with large shields, as in the normal Colubridæ; a loreal pit; eye moderate or small, with vertical pupil. Body moderately elongate or short. Scales keeled (or smooth), with apical pits. Tail moderate or short.

This genus is distributed over nearly the whole of Asia, the eastern parts of the United States of America, and Mexico and Central America. One of the Asiatic species just penetrates into South-Eastern Europe, and is the sole representative of the Crotalinæ in this part of the world.

Form.—Moderately elongate. Head subtriangular, flat or slightly concave above, swollen in the temporal region, very distinct from neck; snout rounded or obtusely pointed, slightly turned up at the end, with obtuse canthus and vertical or slightly oblique loreal region; eye rather small. Tail seven to eight and a half times in the total length.

Head-Shields.—Rostral as deep as broad or slightly broader than deep, just visible from above. A pair of internasals and a pair of larger prefrontals. Frontal as broad as the supraocular, as long as or a little longer than its distance from the end of the snout, as long as or a little shorter than the rather short parietals. Supraocular extending beyond the vertical of the posterior border of the eye. Loreal pit between three shields, separated from the labials. Nostril between two nasals, the posterior of which is separated from the upper preocular by a loreal. Two preoculars, one or two postoculars, and a subocular. Three large lower temporals, anterior largest. Upper labials seven or eight, third and fourth largest, third entering the eye. A pair of small chin-shields.

Scales sharply keeled, with two apical pits, in twenty-three rows. Ventral shields 149 to 174; anal entire; subcaudals 31 to 44 pairs.

Coloration.—Pale yellowish-grey, greyish-brown, or reddish, sometimes greenish in young specimens, with transverse series of darker spots or with more or less regular dark bars with serrated edges across the back (Plate XIV.); these bars may be narrower than the interspaces between them, or so large as to cause the back to appear brown with light cross-bars; the bars sometimes broken up on the vertebral line, and the two halves alternating. The sides usually paler and bearing two alternating longitudinal series of small spots, the lower of which are usually darker, and sometimes extend on the outer ends of the ventral shields. Head pale above, with a dark spot on the middle of the snout, a cross-bar or a pair of spots between the eyes, a spot or short band on each side of the parietal region, and a horseshoe-shaped band on the occiput, the branches of which are more or less produced on the nape; all these markings sometimes confluent. A broad, dark, light-edged band on the temple. Lips whitish, speckled with brown. Lower parts whitish, more or less profusely speckled with grey or brown. The horny shield terminating the tail usually dark brown or black at the end.

Size.—This species rarely reaches a length of 29 inches. The largest specimen in the British Museum measures only 19 inches.

Distribution.—From the north and east coasts of the Caspian Sea, across Central Asia to the Upper Yenissei, as far north as 51°. In Europe it is only known from two arid tracts between the Volga and the Ural, near the Caspian Sea, viz., the Saltan-Murat desert and the Induski hills.

Habits.—Nothing has been published on the habits of this snake, but they are probably similar to those of its near and more eastern relative, A. blomhoffi, Schlegel, which inhabits China and Japan. A. blomhoffi is said to be more or less nocturnal, although showing a predilection for localities well exposed to the sun. It is ovoviviparous. The symptoms of its bite, which is rarely fatal to man, are the same as in the Vipers.

All the species of Ancistrodon, so far as they have been observed, are in the habit of raising and vibrating the tail, like the Rattlesnakes, when coiling themselves up in a defensive attitude.