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.
The "upland moccasin" of the South is the "pilot" or "copperhead" of the North, where it still exists in forested and rocky districts from Connecticut and the Great Lakes to Texas, and is particularly abundant in the rough hills beside the Hudson River, and thence southward along the Alleghenies. Its general hue is yellowish brown, becoming chestnut or coppery red on the head and end of the tail, which terminates in a hard point. Along the back, meeting irregularly on the midline, are chestnut-hued blotches that divide on the sides, forming inverted Y's; the belly is yellowish with distinct black blotches, leaving the throat clear. After one has seen a copperhead he is not likely to confuse it with the milk snake or any other. Its haunts and habits are much the same as those of the eastern rattlesnakes, nor do I consider it any more aggressive in spite of a rather over-blackened reputation, nor so deadly in the effects of its weaker venom. It is bad enough, however, and should be killed on sight wherever children or pet dogs are likely to meet with it. This upland moccasin is named in science Ancistrodon contortrix; its brother species, the water moccasin, is A. piscivorus.
The moccasin is a larger, heavier snake than the copperhead, and a dweller in the sluggish rivers and swamps of the Gulf States and northward to North Carolina and Kentucky. The moccasins commonly lie on the branches of bushes at the edge of the water; and if escape from danger be possible they quickly drop into the water and swim away beneath it to some hiding place. If suddenly surprised they coil and open the mouth widely toward the intruder, showing its white interior that has given them the name "cotton mouth" among the darkies, who fear them greatly, especially as they work in the rice fields. Mexico has a similar species.
Closely allied to the copperhead and moccasins are two very dreadful snakes of the American tropics—the "fer-de-lance" of the French islands of the West Indies, and the "bushmaster" of Brazil. The former reaches a length of six feet, and the bushmaster, or surukuku, as the Indians name it, to twice that length, thus rivaling the great viper of India. Both have all the ferocity and power of their race exaggerated to the limit, and hundreds of human lives are sacrificed to them every year. Every traveler has thrilling tales about them. Leo Miller, a cool-headed man of science, takes very seriously the fear this creature inspires. He reminds us that a bushmaster ten feet long has fangs an inch and a half long, and injects nearly a tablespoonful of poison at a single thrust. A man would survive such a dose but a few minutes. When once a bushmaster fell from a tree branch into his canoe everybody in it sprang overboard, and some narrowly escaped drowning. Such deadly creatures would make the tropical world unendurable were it not that most of the time they are sluggish and peaceful; but a little fright, or a protective instinct in regard to their eggs, sets them off with the suddenness of a released spring.
In taking up the rattlesnakes we have a sure guide in Dr. Leonhard Stejneger's "Report," describing all the species of North America (the group Crotalinæ is confined to this continent, Central America, and a single species in South America). The special peculiarity of the group is the queer "rattle" (crotalus) at the end of the tail. This consists of a series of loosely connected, somewhat cone-shaped, horny capsules, each of which originally covered the terminal vertebra of the tail. On sloughing the skin this covering remains, but is soon pushed away by the new capsule formed beneath, and partly within it, which in turn is pushed out and replaced by a third, and so on, until sometimes a dozen remain linked together; and when the serpent vibrates its tail, as most snakes do when excited, they rattle against one another, the tone of the "music" rising as the excitement, and speed of vibration, increases. The sloughing is irregular as to frequency, however, especially in young individuals, and may not always produce an addition to the rattle, and the appendage itself may be broken, so that the number of pieces, or buttons, in the rattle is not a trustworthy measure of the age of the snake.
The smallest of the crotalids are the ground rattlers (genus Sistrurus), of which we have two species, and there is one in Mexico. The northern kind, widely known by its Indian name "massasauga," ranges from eastern Pennsylvania and Ontario to northern Minnesota and Kansas, and thence to Texas. The Southern States have a second species commonly called "ground rattler." Both are grayish brown with chestnut or darker dorsal blotches, and are inhabitants of the prairies, with their swamps and marshes. The largest do not exceed forty inches, and their bite is correspondingly weak in effect.
The remainder of the rattlesnakes belong to the genus Crotalus.
The commonly seen species of the region east of the dry plains was named Crotalus horridus by Linnæus, and this is one of the few instances in which his name has defied change by the systemists. It formerly was to be found as far east as central Massachusetts, but there, as elsewhere, civilization has killed it off, so that now it survives only in the Appalachian glens, and in thinly settled tracts farther west and south. Its general color above is yellow-brown, below nearly white; and the body is banded with blackish, the bands taking a zigzag form behind the neck, and the tail is black. It rarely exceeds a yard in length, and is, as a rule, timid and nonaggressive; but a good deal remains to be learned about its habits and breeding.
Far more formidable than this is the diamond-back (C. adamanteus) of the low, coastal region from North Carolina to the lower Mississippi River and throughout Florida, where it is far more common than is desirable. This rattler may exceed eight feet in length, and has corresponding power of harm. It is partial to the neighborhood of water, where its ground-running prey is most numerous; hence it is frequently spoken of as the "water rattlesnake," to distinguish it from the banded species, or "timber rattlesnake" of the same region, which is more habituated to forested districts, with rocks. A race of C. horridus, usually large and vicious, exists in the coast swamps, and is locally called the "canebrake rattler." The diamond back itself takes its name from the lozenge-shaped patches of dark color formed on its upper surface by the crossing of diagonal narrow bands of bright yellow on a greenish gray ground. The literature relating to this terrifying snake would fill hundreds of pages. Raymond L. Ditmars of the New York Zoölogical Park, gives this description:
"Most deadly of the North American poisonous snakes, and ranking in size with the largest of the tropical venomous serpents of both the New and the Old World, this huge rattlesnake, with its brilliant and symmetrical markings, is a beautiful and terrible creature. Ever bold and alert, ever retaining its wild nature when captive, there is a certain awe-inspiring grandeur about the coil of this formidable brute; the glittering black eyes, the slowly waving tongue, and the incessant, rasping note of the rattle.... The mere vibration of a step throws the creature upon guard. Taking a deep inhalation, the snake inflates the rough, scaly body, to the tune of a low, rushing sound of air. Shifting the coils to uncover the rattle, this is 'sprung' with the abruptness of an electric bell. There is no hysterical striking, but careful watching, and if the opportunity to effect a blow with the long fangs is presented, the result is generally mortal."
| THE RATTLESNAKE |
| (Crotalus horridus) |
| Beside the snake is the skin it has just discarded |
A large and very showy western analogue of the diamond-back, known by the sinister specific name atrox, occurs from central Texas to California. One of its varieties is red, with darker red markings and a white tail. The familiar rattlesnake of the plains east of the Rocky Mountains is Crotalus confluentus, which is of moderate size and dull hue; its mainstay of food is found among the prairie-dog towns. A similar but smaller species (C. oregonus) takes its place west of the Rockies, from British Columbia to southern California. The "tiger" rattlesnake, yellow barred with black; the "horned" rattler, which, like the Egyptian horned viper, has a trick of advancing sidewise, and consequently has the popular name "sidewinder"; and the slender green rattlesnake, are small species of the deserts along the Mexican border.
[CHAPTER XXII]
BIRDS—KINGS OF THE AIR
A bird is an animal clothed with feathers and having the forelimbs adapted to flight.
The birds constitute a class in the phylum Chordata, and otherwise are combined, in the group Sauropsida, with the Reptilia, with which they agree more closely in anatomy than with any other group, one prominent particular being that both have a single condyle, in contrast with the mammals and amphibians where the condyle is double. In fact primitive reptiles—probably of the stock of dinosaurs—are the ancestors of birds, the divergence having occurred probably in Carboniferous time. Of the earliest divergent forms, the rocks have as yet yielded no specimens, the most ancient bird forms recovered showing a degree of development in the new type that must have been preceded by a long history of evolution from its reptilian source.
| ARCHÆOPTERYX |
| Skeleton of Archæopteryx macrura with indication of feathers |
| (Reconstructed. After Andrea) |
The oldest fossil bird known is that named archæopteryx, whose remains are found in the Jurassic slates of Bavaria, which represent the beginning of the Mesozoic or Age of Reptiles. In much of its anatomy, and in the possession of perfect feathers, it is a true bird, yet it retains many reptilian features. Its body was about the size of a small crow; its legs were rather long, with well-developed feet of four toes suitable to grasping a perch; its wings were short and probably feeble, for the shoulder girdle and ribs are weak and the sternum is rudimentary. It is plain that it was arboreal in habits, but a poor flyer, and was aided in scrambling about the branches of trees on whose leaves and bark it may have fed, by the fact that three digits of the rather lizardlike wing hand terminated in strong claws, while the thumb was entirely free.
The practical value of this clawed hand is illustrated in a living bird—the hoatzin, of northern South America—which exhibits in several ways the probable appearance and manners of the archæopteryx. "It haunts the sides of lagoons and rivers where a thick growth of low trees projects over the stream or the mud left bare by the tide. When disturbed the bird flies off awkwardly with a violent flapping motion, or leaps from bough to bough, erecting its crest and expanding its wings and tail. The note is sharp and shrill, and has been described as a hissing screech. The food consists of leaves and fruit. The conspicuous nest, placed on low trees or shrubs, is a loose platform of spiny sticks and twigs with a softer lining, and contains from three to five yellowish eggs, spotted with reddish brown and lilac. The young, which can see and run as soon as they are hatched, have a claw on both forefinger and thumb, by means of which they creep about the thickets, and hook themselves over the branches, assisted by the bill and feet. They can also swim and dive."
The most striking features of the archæopteryx were its head and tail. The skull is fairly avine, and the rather short and blunt bill was furnished with conical teeth, nearly equal in size, and set in a marginal row in distinct sockets. Still more lizardlike was the tail—a prolongation of the backbone nearly as long as the body, along each side of which sprouted strong feathers forming a horizontally flat tail with a rounded end.
| TOOTHED BIRD |
| (Hesperornis regalis) |
| Skeleton of toothed bird (After Marsh) |
The next that we know of bird evolution is derived from the discovery of the fossil remains of toothed birds in the Upper Cretaceous formations of Kansas—that is, in the more recent half of the Mesozoic Age. They differ greatly not only from archæopteryx but from each other, and are represented by several species. One type (Hesperornis) was a wingless, diving bird of great size, whose long, heronlike beak was studded with small, sharp teeth, all alike, implanted in a continuous groove; its legs were so hinged to the compressed pelvis that they could be extended almost level with the back, and the lobed toes thus became lateral winglike paddles of great power. The other type, represented by Ichthyornis and its relatives, also had a long, stout bill set with teeth, but each in a separate socket. Ichthyornis was about the size of a pigeon, and its strongly developed wing bones and deeply keeled sternum show that it was a bird of powerful flight, and apparently gull-like habits. So far as we know neither of these Cretaceous birds had any progeny. When, after an immensely long period, other fossils come to light in rocks of the middle Tertiary period they bear few traces of ancestry, and exhibit little relation to the great mass of modern orders. They are the "flightless birds," possessing no wings but running about on massive legs; and the group includes the extinct æpyornis, dinornis, and moa, and the existing ostriches, rheas, emus, cassowaries, and kiwis. Some ornithologists question whether this "ratite" group, characterized by having no "keel" on the sternum, did not have an origin and line of descent quite distinct from those of both the Cretaceous toothed birds and the modern "carinate" type which possess a medial crest or "keel" on the breastbone for the support of the flight muscles; but the more general opinion is that they are a variant from very early birds with wings.