Hydrophis e.g. H. obscura.–The body is long; the head and neck are very slender, the body becoming much thicker farther back. The small teeth behind the poison-fangs are not grooved. The ventral scales are very small, the others are keeled, strongly so in the males. The general coloration of this Sea-Snake, which reaches about one yard in length, is dark olive-green above with yellowish cross-bars, which form complete rings round the slender part of the body. Other specimens are pale olive, with dark cross-bands. This species occurs in the Bay of Bengal and the Malay Archipelago.

As a rule Sea-Snakes are not found in mid-ocean. After leaving Ceylon, the steamer meets them again in the Straits of Malacca. Those which occur near the south coast of Japan, e.g. Distira cyanocincta, are found there only in the summer, and are probably carried there by the south-west monsoon.

According to Semper the gravid female visits the shores of low islands, there to give birth to its young between the rocks, and she remains with her offspring for some time. Semper once found a large female, probably Platurus fasciatus s. colubrinus, coiled up amongst rocks, and between the folds were at least twenty young, each already about 2 feet long.

Boulenger^[193] has written an interesting popular account of Sea-Snakes.

Fam. 8. Amblycephalidae.–Some thirty species of Neotropical and Oriental Snakes have been separated from the Colubridae on account of the pterygoids, which are widely separated from the quadrates, the posterior ends of the pterygoids not reaching beyond the level of the occipital condyle. This condition can be ascertained when the mouth is opened widely. The prefrontals are not in contact with the nasals. The squamosals are reduced to pad-like vestiges. Externally the Amblycephalidae are easily distinguished from the Colubridae by the absence of a longitudinal median mental groove. The head is thick, very distinct from the neck, and gives these harmless snakes a "poisonous" appearance. The pupil is vertical.

Amblycephalus, e.g. A. monticola.–Maxillaries short, with only five or six teeth. Sub-caudals in two rows. Body compressed, covered with fifteen rows of scales. South-Eastern Asia.

Fam. 9. Viperidae.–The maxillaries are very short, movably attached to the prefrontals and ectopterygoids, so that they can be erected together with the large poison-fangs, which (besides reserve-teeth) are the only maxillary teeth. The prefrontals are not in contact with the nasals. The squamosals are very loosely attached. For further details see Fig. 180. The poison-fangs are perforated, having a wide hole on the anterior side at the base, in connexion with the large poison-gland; the hole leads into a canal, which opens gradually as a semi-canal on the anterior surface of the distal third or quarter of the tooth. As usual in poisonous snakes, several reserve-teeth are stowed away behind the acting fang. When the latter is broken off or has served its time it is cast off at the base, and the next reserve tooth takes its place. The supply of reserve-teeth is indefinite, half-finished teeth down to mere germs constantly growing.

All the Viperidae are very poisonous, and all, except the African Atractaspis, are viviparous. They include terrestrial, arboreal, semi-aquatic, and burrowing types. The family is cosmopolitan, excepting Madagascar and the whole of the Australian region; it is divided into Vipers and Pit-Vipers.

Sub-Fam. 1. Viperinae (Vipers).–There is no sensory external pit between the eye and the nose, and the maxillary is not hollowed out above. The Vipers are absolutely restricted to the Old World, ranging over the whole of Europe, Africa, and Asia, with the exception of Madagascar; their northern extension is limited only by the permanently frozen condition of the underground. Nine genera with about forty species are known.

Causus with a few species in Africa and Azemiops feae in Upper Burmah are the only vipers which have the head covered with large symmetrical shields, while in the other genera the head-shields are broken up into scales or small shields. Causus rhombeatus is very common in Africa, from the Gambia to the Cape. It reaches a length of a little more than 2 feet. Pale olive-brown above, usually with a dorsal series of large rhombic or V-shaped dark brown, sometimes white-edged spots, and with a dark arrow-shaped mark on the occiput; under parts yellowish white or grey.

Bitis s. Echidna.–Very much like Vipera, but the nasal shields are separated from the rostral by small scales, and the postfrontal bone is very large. Several species in Africa.

The head is very distinct from the neck, chiefly owing to the large poison-glands and to its being, like the body, much depressed. The small eye has a vertical pupil, and is separated from the labials by a series of small scales. The scales are keeled, and form many, from twenty-nine to forty-one, rows; the tail is very short, with two rows of scales below.

In B. arietans, the "Puff Adder," the nostrils are directed upwards. This ugly brute is yellowish to orange brown above with regular, chevron-shaped dark bars or other markings, helping to conceal the creature when it is lying on sandy and stony ground; the under parts are yellowish white. The Puff Adder reaches a length of 4, or very rarely 5 feet, ranging all over Africa, except the north coast, and extending into Southern Arabia. It is very slow, and trusts to not being discovered when lying in the dry grass; when approached it inflates the body and hisses loudly with a puffing sound, watches the enemy with raised and characteristically bent head and neck; but it bites only when actually touched or attacked. The effect of the bite is very dangerous. Its prey consists chiefly of small mammals, which are hunted during the night.

B. (Echidna) nasicornis, of Tropical West Africa, has two or three enlarged scales above the supranasals; they stand upon erectile tissue so as to form horn-like elevations. This "Nose-horned Viper" grows to a length of 4 feet, and is rather prettily marked; the ground-colour is purplish or reddish brown, with a vertebral series of large, pale, dark-edged spots and oblique crosses. The young are at birth as much as one foot in length, and are very tastefully coloured.

Cerastes and Echis prefer to burrow in sand. The lateral scales are smaller than the dorsals, and arranged obliquely with serrated keels, so that the snakes can cover themselves with sand by lateral shovelling motions of the sides of the body.

Cerastes cornutus, the "Horned Viper" of North-Eastern Africa, from Algeria to Arabia, extending also into Palestine, has the sides of the ventral scales bent angularly, with an obtuse keel on either side. Above each eye stands a large horny, spiky scale. The upper parts are pale yellowish brown, mostly with dark spots arranged in several longitudinal rows. The under parts are white. This, or perhaps C. vipera, which has no horns, is supposed to be the species which has become famous through the suicide of Cleopatra.

About twenty years ago a number of "Horned Vipers" were brought to the Zoological Gardens of London, and attracted attention by their unusually long horns. It was found that some wily Egyptian snake-catcher had tried to manufacture a new species by taking specimens of the hornless C. vipera and inserting a pair of hedgehog's spines, pushing them upwards through the mouth.

The "Horned Viper" attains a length of two feet and a half. In the daytime it is invisible, being buried in the sand with only the eyes, nostrils, and the "horns" appearing above the surface.

Vipera.–The head is distinct from the neck, and is covered with small scales and a few larger shields. The eye is separated from the labials by scales; the nasals are in contact with the rostral shield or separated by one naso-rostral shield. The scales on the body are strongly keeled; they are in two rows on the short tail. This genus with about ten species ranges over Europe, Asia, and the greater part of Africa.

V. berus, the Common European Viper (see Fig. 165, p. 620). The snout is not turned up at the end; between the small head-scales there is generally a pair of well-developed parietal and frontal shields. The scales of the trunk form twenty-one rows. The coloration is very variable, there being grey, brown, red, or black specimens in the same country, and the much-spoken-of black zigzag line along the back is so often indistinct that it is a character not to be relied upon. Usually the grey, yellowish, olive, brown or red ground-colour is set off by a dark zigzag band along the spine, and by a series of lateral spots; an oblique or St. Andrew's cross or two diverging bold streaks of dark brown or black are usually present on the back of the head, and there is a dark streak behind the eye. The under parts are grey, brown, or black, uniform or speckled; the end of the tail is usually yellow or red.

According to Boulenger, who is making a special study of the individual variations of Vipers (concerning colour, scaling, number of vertebrae, etc.), some specimens are entirely black in the males through extension of the black markings, in the females through darkening of the ground-colour. Males are usually distinguishable from females by darker, deep black markings and lighter ground-colour. The females are mostly larger than the males. The largest specimen in the British Museum measures 700 mm. = 28 inches, but a viper 2 feet long may be considered a very large specimen. The Common Viper has a wide range, from Wales to Saghalien Island, and from Caithness to the north of Spain. It ascends the Alps to a considerable altitude, up to 6000 feet. J. Blum^[194] has published an elaborate statistical account of the Viper in Germany, unfortunately confining himself strictly to the political frontiers. According to the map attached to his work, the Viper is common all over Germany with the exception of South-Western and parts of Middle Germany. It is absent in Alsace, the Bavarian Palatinate, Rhenish Prussia, Hesse, the northern half of Baden, Würtemberg, and Franconia, countries which, speaking broadly, have a warm subsoil, composed of Red Sandstone and Basaltic formation. As a rule the Viper prefers heaths, moors, and mixed woods with sunny slopes. Brambles, clumps of nettles, hedges, the edges of little copses, heaps of stones, are favourite places of retreat, affording shelter, holes, and the vicinity of mice, which form its chief sustenance. At harvest-time it is often found in cornfields, and it frequently hides in the sheaves. Vipers are fond of basking on certain spots, on the top of a stone, the stump of a tree, or a patch of sand: a shower of rain or even passing clouds drive them back into their holes. They are eminently nocturnal, when they regularly "beat" their district, biting and paralysing their prey before swallowing it. A fire kindled at night is sure to draw vipers near; the same applies to other vipers, for instance Cerastes, which appears in perplexing numbers at the camp-fire. They cannot climb, and they avoid going into water. The pairing takes place as a rule from March to May, a number of individuals, mostly males, collecting around the females, and forming entangled lumps of snakes; parturition takes place in the following July and August. In exceptionally warm winters they have been known to pair in December, having left their winter-quarters. They hibernate for about six months, more or less according to the climate, congregating in great numbers, sometimes in dozens. With very rare exceptions Vipers do not take food in captivity, but prefer starving themselves to death. The bite is as a rule not fatal. The seriousness of the case depends of course upon many circumstances, as for instance the state of concentration of the venom, the position and depth of the bite, and last but not least upon the general condition of health of the victim. General depression aggravated by nervousness, weakness of the bitten limb, occasional breaking out of the wound, are of frequent and protracted occurrence. (See also p. 590.)

V. aspis is a more southern and western European Viper, occurring from France to the Tyrol, and in Italy. The snout is slightly turned up at the end, and still more so in V. latastei of Spain and Portugal. In V. ammodytes, of South-Eastern Europe, the raised portion is produced into a soft, scaly appendage (see the lower figure on p. 641). Vipers are sometimes unpleasantly common in certain localities. This was for instance the case at the drill-ground near Metz, and the military authorities paid a price for each viper delivered to them. The supply of the latter increased to an alarming extent until the German authorities discovered that a regular trade had been established across the frontier, and that the French Lorrainers were importing vipers briskly.

V. russelli, the "Daboia" or Russell's Viper, is one of the scourges of India, Ceylon, Burma, and Siam. The scales form about thirty rows on the body. The upper surface of the head is covered with small, imbricating, usually keeled scales. The general colour is pale brown above with three longitudinal series of black, light-edged rings, which sometimes encircle reddish spots. The under parts are yellowish white, uniform, or with small crescentic black spots. Total length up to about 5 feet. The poisoning symptoms are described on p. 590.

Sub-Fam. 2. Crotalinae ("Pit-Vipers").–With a deep cavity or pit between the eye and the nose, lodged in the hollowed-out maxillary bone. This pit is lined with a modified continuation of the epidermis, and is amply supplied with branches from the trigeminal nerve. It is undoubtedly sensory, but we do not know its function. A good anatomical account of this organ has been given by West.^[195] Some of the Pit-Vipers have a rattle at the end of the tail; these are the Rattle-Snakes. The rattle is composed of a number of horny bells which fit into each other. The oldest or terminal bell is in reality the horny covering of the tip of the tail, and with each moult or shedding of the skin the youngest bell becomes loose, but is held by the new covering which has been developed in the meantime. There is thus produced an ever-increasing number of loosely-jointed bells, but now and then most or all the bells break off, probably when they are worn out, and a new set is gradually developed. Rattles with a dozen bells are, for instance, very rare. They naturally increase in bulk with the age of the snake, but the number of joints is no indication of the snake's age.

Pit-Vipers have a very wide distribution. They are divided into four genera with about sixty species. Rattle-Snakes are restricted to America, but other Pit-Vipers occur in North and South America and in the southern half of Asia.

Ancistrodon.–Without a rattle. The upper surface of the head is covered with nine large shields, but the internasals and prefrontals are sometimes broken up into scales. The scales of the body have apical, sensory pits. About ten species, some in Central and North America, others in the Caspian district (A. halys), in the Himalayas (A. himalayanus), in Ceylon, Java, etc.

A. piscivorus s. Trigonocephalus cenchris (part), the "Water-Viper," inhabits North America from Carolina and Indiana to Florida and Texas. The general colour is reddish to dark brown, with darker cross-bands or with C-shaped markings; a dark, light-edged band extends from the eye to the angle of the mouth. The under parts are yellowish, spotted with black, or the latter is the prevailing colour. Total length up to 5 feet. The Water-Viper is semi-aquatic and lives chiefly on fishes, but it also eats other snakes and various Amphibia, Birds, and Mammals. This snake is very good-humoured in captivity, and becomes easily tame. A gentleman in Berlin, rather too much addicted to making pets of poisonous snakes, had a pair which propagated regularly. When I was a boy he invited me to feed the young Water-Vipers with fishes cut into strips, and I enjoyed this immensely until he warned me not to touch the mother, which might bite strangers.

A. contortrix s. Trigonocephalus cenchris (part), the "Moccasin-Snake" or "Copper-head," is one of the few poisonous snakes which possess a loreal shield, i.e. a shield intercalated between the pre-oculars and the nasals; below it lies the pit. The general colour is yellowish to pink or pale brown, with dark brown or red cross-bars or triangular marks. The under surface is yellowish or reddish, speckled with grey or brown, and with a lateral series of large blackish spots. Total length of full-grown specimens about one yard. The Moccasin-Snake ranges from Massachusetts and Kansas to Northern Florida and Texas. It prefers swampy localities or meadows with high grass, where it hunts for small Mammals and Birds.

Lachesis.–Without a rattle. The upper surface of the head is covered with very small shields or with scales. About forty species in South-Eastern Asia and in Central and South America.

L. (Bothrops s. Craspedocephalus) lanceolatus inhabits nearly the whole of South America, extending into Mexico and the Lower Antilles, e.g. Martinique, Guadaloupe, and Santa Lucia, where it is known as the "Fer-de-Lance," and is the curse of the sugar-plantations on account of its being so very common and so deadly poisonous. The Mongoose was introduced as a possible antagonist, but the little Indian Mammal wisely left the dangerous reptile alone, and has in some places established himself as another pest–as a destroyer of poultry. The Fer-de-Lance grows to a length of 6 feet, establishes itself everywhere–in swamps, plantations, forests, in the plains and in the hills–and is very prolific, producing, according to its size, dozens of young which are 10 inches long, very active and snappy.

L. (Trimeresurus) gramineus s. viridis, to mention one Asiatic species, grows to less than 3 feet in length, is bright green above, sometimes with faint blackish bars; green, yellow, or whitish below, and with a light streak along the outer row of scales. The end of the tail is usually bright red. This beautiful snake has a prehensile tail and is arboreal. Its range extends over the whole of India, to Hong-Kong and to Timor, and even into the Andaman and Nicobar Islands.

Sistrurus.–With a rattle. The upper surface of the head is covered with nine large shields. A few species in North America east of the Rocky Mountains, e.g. S. miliarius.

Crotalus.–With a rattle. The upper surface of the head is covered with small scales. Range from Southern Canada and British Columbia to Northern Argentina, but not in the West Indian Islands. About ten, mostly closely-allied species.

The effect of the poison of Rattle-Snakes has been discussed on p. 589.

C. horridus is the common Rattle-Snake of the United States; C. confluentus is the species in Western and C. durissus the common species in South-Eastern North America. Very large Rattle-Snakes, C. durissus, attain a length of 8 feet, others not often more than five. They prey chiefly upon small Mammals, hunting for them at night. In the daytime they are also about, mainly in order to bask. Although they occasionally take to the water in pursuit of their prey, they dislike being wetted by rain, withdrawing then into their holes, appropriating as a rule those of ground-squirrels, rats, and Prairie-dogs. The often-repeated story about Rattle-Snakes living in neighbourly friendship in the holes of Prairie-dogs, together with the little Prairie-owls, is an exaggeration. We do not know how many of the original inmates are eaten. Pairing takes place in the spring. During the cold months they hibernate under ground, often in considerable numbers.

Rattle-Snakes have few enemies besides man and pigs. The latter kill and eat them wherever they can. The rattle is decidedly useful to the snake as an instrument of warning off any approaching possible enemy, since no snake likes to bite unless in self-defence or in order to kill its prey. The noise of the rattle is very loud in dry weather, much duller on clammy days; it is a shrill sound like that of a rattling alarm-clock, and a well-conditioned snake in a room can make conversation well-nigh impossible, and can keep on rattling for half an hour or longer. The rattle is kept in such rapid lateral vibrations that it shows only a blurred image, the rattle standing with its broader sides vertically, not horizontally. They endure captivity for many years, and become tame enough not to hiss and to rattle whenever they are approached.

C. horridus is grey-brown above, usually with a rusty vertebral stripe and with V- or M-shaped blackish cross-bands; the under surface is yellowish; the end of the tail is blackish. The supra-ocular shields are smooth and much narrower than the scaly space between them, and there is only one pair of internasals.

C. durissus s. adamanteus differs from the previous species chiefly by possessing two pairs of internasals; and the dark markings on the body form a handsome pattern of rhombs with lighter centres and yellowish edges. This is the largest species of Rattle-Snake, reaching a length of 8 feet.

C. confluentus has broader, transversely striated, supra-ocular shields. The specific name refers to the continuous series of large brown or red rhomboidal spots on the back.

C. terrificus ranges from Arizona to Argentina, and is the only species of Rattle-Snake in South America. It differs from the others by having a pair of prefrontal shields behind the pair of internasals.

INDEX