CORAL SNAKES, COBRAS, AND SEA SNAKES
The flattening of the head and neck practiced by the hognose as a gesture of readiness to fight, whether true or false in its implication of ability, is found among several non-poisonous colubrids elsewhere and indicates their approach in kinship to the "hooded" cobras that are the foremost representatives of the venom-bearing members of the Colubridæ. It will be recalled that we have been sketching the "harmless" section (Aglypha), and have now to take up the two remaining "dangerous" sections of the Colubridæ, the Opisthoglypha and the Proteroglypha.
The principal tooth-bearing bone in a serpent's mouth is the forward half of the upper jaw, termed the maxillary. The maxillary of each side is connected with its fellow by a small, single bone in front (the premaxillary) and otherwise is connected with the loosely connected bones of the skull by those elastic cartilages that enable the mouth to expand and take in prey of a size more than equal to the snake's head when the mouth is shut. In the serpents that do not possess a poisoning apparatus the teeth on the maxillaries are alike in size, and solid; but in the venomous kinds some of the teeth are enlarged and grooved or channeled to conduct a flow of poison into the wound made by biting. This is the case with the poison-bearing sections of the Colubridæ mentioned above, and their difference is in the relative position of the poison-conducting teeth or "fangs" on the maxillaries.
In the Opisthoglyphs these teeth are situated near the posterior end of the maxillary, and are grooved on the rear side, where they receive the poisonous fluid from a sac in the cheek. The greater number of species of this group are residents of the Old World, although we have several representatives along our Mexican border, and more southward, especially in the tropics. Most of them are little dangerous to mankind, as it is difficult for them to inflict a wound by "striking." They first seize their prey and then use their rather short fangs. The poison has a paralyzing effect, reducing the victim to helplessness. Some of these snakes must be regarded as decidedly dangerous, but fortunately all the American species may be quickly recognized by the peculiar marking on their heads, which has given the name "jew's-harp snake" to a common species of Arizona. It is believed that the vipers are an offshoot of an opisthoglyph ancestry, in spite of the forward position of their fangs.
In the Proteroglypha, on the contrary, the poisoning teeth, in all cases small, are situated near the front of the maxillaries, and they are much more dangerous reptiles, for they include the coral snakes and cobras (Elapinæ) and the sea snakes (Homalopsinæ), which are able to strike their teeth into anything they successfully attack.
The coral snakes (genus Elaps) derive their name from the broad bands of coral-red that encircle their bodies in most species, with narrow rings of black and yellow between. These brilliant colors, combined with the luster of the smooth scales, make them among the most beautiful of serpents, and a common species of our Southern States is called the harlequin. The genus is exclusively American, and nearly all belong to the tropics, where the largest become five feet long, and their bite is deadly to man. They keep to the ground, and much of the time under it, and are cannibalistic in their diet. The body is slender and cylindrical, the head small, and the eyes like beads. They are indocile, quick-tempered, and very dangerous to handle, despite the fact that they do not always resist being disturbed. Hence the widely prevalent opinion that they are harmless is a perilous delusion fostered by the fact that certain innocuous southern serpents closely mimic the coral snakes in size and colors. It should be learned and remembered, especially by visitors to winter resorts in Florida, that the poisonous ones (Elaps) have the black rings bordered on each side by the yellow ones, while in the harmless species the yellow rings are bordered by the black; also, in the coral snakes the bands of color completely encircle the body, but do not in the other kind. A very elaborate illustrated account of the coral snake and its poison apparatus, methods and serious effects, was given by Stejneger in the "Annual Report of the United States National Museum," for 1893, Part II.
The remainder of the elapine serpents (about 125 species) belong to Africa and the Orient. Typical of them are the cobras of the genus Naja, of which the species (Naja tripudians) met with from Turkestan to southern China and the Malay islands, and named by Portuguese explorers "cobra de capello" (hooded snake), is world-famous. Several species inhabit Africa and differ little from the Indian cobras, but are equally deadly. The fangs in all this group are small and are fixed in the extreme front of the upper jaw, not being erectile like the long fangs of the rattlesnakes and vipers. Cobras vary much in coloration, and Mr. Scully reports that he has killed South African specimens of light yellow, jet black and all intermediate hues.
The cobra is a fierce fighter and, when reared up, with expanded hood, looks very formidable. Anterior to the head the ribs lengthen and then gradually shorten to normal dimensions. These lengthened ribs, about twenty in number, lie, when the snake is quiescent, more or less laterally along the spine. But when the snake becomes excited, the neck bends and the ribs spring out at right angles. Over them the loose folds of skin expand umbrella fashion. When much enraged, the cobra spits drops of venom at its enemy. These are propelled a distance of about four feet.
The cobra is found all over South Africa, but is especially plentiful in the dry, sandy deserts northwest of the Cape. There extensive colonies of large mice abound, patches of ground being thickly honeycombed with burrows. In these the cobras dwell—apparently, as in the case of the puff adders, on the best of terms with their hosts, upon whom they principally feed, reminding one of the tenancy by the Western rattlesnake of prairie-dog "towns."
A close relative of the cobra is the ringhals (i. e., ringneck), known as the "spitting snake," the explanation of which Mr. Scully furnishes from personal experience thus:
"The ringhals, when excited, exudes a quantity of venom, which drips down the fangs and lodges behind the abrupt, horny, lower lip. Upon this the angry snake directs a blast of air through its extensible windpipe, with the effect that a jet of fine venom spray is emitted toward an enemy. This jet may reach a height of six feet. That the eyes are aimed at I have proved by experiment. If the poison reaches them blindness, which may be permanent, results. The bite of the ringhals is highly venomous, but the snake appears to prefer disabling its enemy by means of the spray of venom."
The most novel and interesting of Mr. Scully's contributions to African herpetology, however, is his story of the mamba (Dendraspis angusticeps), which he calls "the head of the family." It is the longest venomous snake in the world, probably running to fifteen feet in exceptional cases, but is slender and primarily a tree snake. This naturalist declares it to be the most dangerous of all snakes, as it is highly aggressive at times and its speed is quite extraordinary. If disturbed during the pairing season, the mamba attacks without hesitation; and if at any time one happens to get between the mamba and its dwelling, the snake rushes straight for its objective and, in passing, strikes swift as lightning at the intruder. It progresses in a series of bounds, suggestive of the successive uncoilings of a steel spring. There are two varieties, one colored a vivid grass-green, the other steely black, both so dreaded that the news that a large mamba has been seen will cause the vicinity to be shunned—perhaps for months.
"The mamba has the habit of lying coiled among the branches adjacent to a footpath in a forest. Woe to the passing wayfarer in such a case! If he touch a twig, and thus impart the least tremor to the snake's lair, a lightning-swift stroke upon face, neck, or arm seals his doom. Such a stroke may be delivered either forward or sideways, with equal speed and effectiveness."
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).