The most feared of the cobra tribe in India and eastward is the king cobra, or hamadryad, which often exceeds a dozen feet in length and is "the largest, boldest and most dangerous of all venomous snakes," in Boulenger's opinion, "for when disturbed it does not content itself with merely sitting up and expanding its hood, but will almost invariably attack." Fortunately it is not numerous anywhere in its range from the Himalayas to the Far East; and it is useful in that it feeds exclusively on snakes, small pythons, kraits, rat snakes, and the common cobra. Its bite will kill a man in an hour or two; and it is recorded that an elephant bitten by one died in three hours.
Nearly all the serpents of Australia belong to Elapinæ, and are exceedingly dangerous. Among them are the "black snakes," the females of which are called "brown adders"; the "tiger," so called from its colors; and most dreaded of all, the "death adder," which is distinguished by a peculiar tail end, and by the fact that the head is made distinct from the body by a narrow neck, giving it a viperlike appearance. When disturbed it flattens out the whole body.
A few words about the sea snakes will close our account of the poison-bearing colubrids. These are set apart in the subfamily Homalopsinæ, on account of the structure of the tail, which is flattened vertically into a combination of swimming organ and rudder, for they live in the estuaries of Oriental rivers, and go far out to sea in their search for food; and are to be met with from the Persian Gulf to Polynesia and Japan. All are very poisonous, feed mainly on fishes and produce living young; and all are clothed in varied and brilliant colors. Living in the sea, or in tidal inlets, their movements in the clear blue water are agile and elegant; and in the Bay of Bengal they are sometimes seen congregating in large shoals.
We turn now to the last and most advanced family of serpents, the vipers, rattlesnakes, moccasins, copperheads, and so forth (Viperidæ).
VIPERS, MOCCASINS AND RATTLESNAKES
"Viper" is an old French-Latin word, meaning "bearing living young," which was noted as distinctive from the egg-laying habit of other snakes, and peculiar to the single species that the people of southern Europe knew—the small Vipera verus, or asp, from which the large and widespread family derives its name. The vipers differ from the colubrids in important particulars. Their bodies are thick in proportion to their length, which rarely exceeds six feet, and this and their weight make them unable to run rapidly or (with one exception) to climb trees. The sturdy body narrows into a slender neck supporting a distinct head, given a flattened, triangular form by the expansion of the hind head on each side to accommodate the great poison sacs with which these snakes are provided. The maxillary is a stout bone in the fore part of the upper jaw, and carries on each side a long, backward-curved fang, which is tubular and is connected at its root with the extremity of a duct from the poison sac. When the serpent's mouth is closed, or it is swallowing anything, these fangs, which in a large snake may be an inch and a half long, lie back in a fold of the flesh out of the way; but when the mouth is widely opened they spring forward, and when the head is darted forward to strike a prey or an enemy, they are driven down into its flesh and the venom spurts through them into the wound, with benumbing and deadly effect. They are frequently broken or dragged out, and then new ones arise from behind to replace them. The eye is large, dull, and catlike in its pupil; the scales are strongly keeled and dull in hue in the desert dwellers, but often gay with colors in intricate patterns in the forest dwellers; and the short and stumpy tail may end in "rattles," or a horny tip, or neither. Nearly all give birth to large broods, which are as vicious at birth as are their mothers. The family has two sections, marked by the absence in the first, and the presence in the second section, of a deep pit in the broad scale on the head between the nostril and the eye.
The original little "viper" of Europe and Asia is more a nuisance than a peril, for it is rarely more than a foot long, and its bite would be fatal only to a small child. A larger species, the sand viper, ranges from Italy to Armenia. India, Burma and Siam, however, have a member of this group which is pronounced by Sir J. Fayrer as next to the cobra the most dangerous serpent of the East—the daboia, or Russell's viper. It is nocturnal, not aggressive, and makes a loud hissing when anyone comes near it, so that it does not cause as many human deaths as it might; but frequently kills grazing cattle by biting them on the nose. The greatest and worst of these snakes belong to Africa, where the northern deserts are infested with two greatly dreaded species—the horned and the saw vipers. The former has two sharp hornlike protuberances above the eyes, and Canon Tristram writes that its usual habit is to coil itself on the sand, where it basks in the impress of a camel's footmark, and thence suddenly to dart out on any passing animal. Horses as well as men are in constant terror of it, for it will attack without any provocation.
The worst of the African vipers, nevertheless, is the puff adder, which ranges over the whole continent, and may grow to a length of six feet, with a girth equal to a man's thigh.
"The coloration of the puff adder," Mr. Scully writes, "is in groundwork a series of delicate browns, with more or less regular curved transverse patches darkening to black and edged with vivid yellow. Its scales are keeled; its short tail tapers suddenly to a point. It is a sluggish creature, incapable of swift progression. When disturbed, it flattens itself to the ground, the air expressed in the process causing the warning hiss which has saved many a life. But if the foot of the intruder touch it, or even tread in its immediate vicinity, the puff adder lunges either forward or sideways, with a swiftness that the human eye cannot follow, and, having buried its fangs deep in the flesh, holds on like a bulldog, forcing two streams of venom into the tissues. The expression of this snake—its square muzzle and glaring, lidless eyes with vertical pupils—the extraordinary gape of the jaws and the huge, erected fangs, form what is probably one of the most fiendishly menacing combinations in nature. Nevertheless, apart from its head, the puff adder is a creature of great beauty. The 'night adder' (Causus rhombeatus) is much dreaded on account of its habit of lying at night in pathways and failing to move out of one's way. This snake is one of the exceptions to the rule of the viper class, in that it is not viviparous. It has another remarkable peculiarity: the poison glands, instead of lying compactly embedded in the maxillary muscles above the angle of the jaw, are much elongated, and lie one on each side of the spine."
All the pit vipers are American except a few species in southern Asia, some of which are arboreal in habit and have red prehensile tails. Our American species fall into two genera: Ancistrodon, the moccasins (no rattles), and Crotalus, the rattlesnakes.