1902 Encyclopedia > Snakes
SNAKES constitute an order (Ophidia) in the class of Reptiles which is characterized by an exceedingly elongate body, cylindrical or sub-cylindrical, and terminating in a tapering tail. The integuments are folded into flat imbricate scales, which are rarely tubercular or granular. The spinal column consists of a very great number of vertebrae, with which the numerous ribs are movably articulated. Limbs are entirely absent, or only rudiments of the posterior occur more or less hidden below the skin; there is no sternum. The bones of the palate and jaws are movable; the mandibles are united in front by an elastic ligament and are very distensible. Generally both jaws and the palate are toothed, the teeth being thin and needle-like. There are no eyelids, no ear-opening. The vent is a transverse slit.
Snakes and lizards. Great as is the difference in appearance between a typical snake and a typical lizard, the two orders of Opbidians and Lacertilians are nearly allied; the former is probably merely a specialized descendant of the latter or of the pythonomorphous reptiles, or perhaps of both. Moreover, the living Lacertilians include forms which approach the Ophidians by having a greatly increased number of vertebrae, a much advanced degradation of the scapular and pelvic arches and limbs, a simple dentition, and the absence of eyelids and external ear-opening. And on the other hand we find Ophidians with a greatly diminished flexibility of the vertebral column, with closely adherent, smooth and polished scales, with a narrow mouthtotally unlike the enormous gape of the typical snakesand even without that longitudinal fold in the median line of the chin which is so characteristic of the order (Typhlopidae). Thus of the Ophidian characters as given above only that taken from the loose connexion of the bones of the skull remains as a sharp line of separation between snakes and lizards. The mandibulary symphysis is not by suture but by an elastic band; the intermaxillary, palatine, and pterygoid bones are so loosely attached to the cranium that they can be easily pressed outwards and forwards, and the maxillary and mandibulary of one side can be moved in those directions indepedently of their fellows opposite. The intermaxillary is small, generally toothless, and coalesces with the nasals and vomer into a single movable bone ; finally, the suspensory is much elongate and movable at both ends. This arrangement ensures an extraordinary degree of mobility and elasticity of all parts of the gape, which, however, varies in the different families of the order. For the other characteristic points of their structure and for their distribution, see REPTILES.
Distribution and habits. The number of known species of snakes has been given as 1500 by some authorities and as 1800 by others. The limits of their distribution seem to be the 70th parallel N. lat. in Europe, the 54th in British Columbia, and the 40th parallel S. lat. in the southern hemisphere. The number of species and of individuals in a species is small in the temperate zones, but increases as the tropics are approached. In the tropical zone they are abundant, especially where a well-watered soil nourishes a rich vegetation, with glades open to the sun, and where a variety of small animals serve as an abundant and easily obtained prey. It is in the tropics also that the largest (boas, pythons) and the most specialized kinds occur (tree snakes, sea snakes, the large poisonous snakes). On the other hand, every variety of soil is tenanted by some kind of snakes : they form a contingent in every desert fauna. In accordance with this general distribution snakes show a great amount of differentiation with regard to their mode of life and general organization ; and from the appearance alone of a snake a safe conclusion can be drawn as to its habits. The following categories may be distinguished.
(1) Burrowing snakes, which live under ground and but rarely appear on the surface. They have a cylindrical rigid body, covered with generally smooth and polished scales ; a short strong tail ; a short rounded or pointed head with narrow mouth; teeth few in number; small or rudimentary eye; no abdominal scutes or only narrow ones. They feed chiefly on invertebrate animals, and none are poisonous. (2) Ground snakes, living chiefly on the ground, and rarely ascending bushes or entering water. Their body is cylindrical, flexible in every part, covered with smooth or keeled scales, and provided with broad ventral and subcaudal scutes. All the various parts of their body and head are well proportioned; the non-poisonous kinds of ground snakes are in fact the typical and least specialized snakes, and more numerous than any of the other kinds. They feed chiefly on terrestrial vertebrates. The majority are non-poisonous; but the majority of poisonous snakes must be referred to this category. (3) Tree snakes, which are able to climb bushes or trees with facility or pass even the greater part of their existence on trees. Their body is rarely cylindrical, generally compressed and slender; their broad ventral scutes are. often carinate on the sides. Those kinds which have a less elongate and cylindrical body possess a distinctly prehensile tail. The eye is generally large. Their coloration consists often of bright hues, and sometimes resembles that of their surroundings. They feed on animals which likewise lead an arboreal life, rarely on eggs. Poisonous as well as innocuous snakes are represented in this category. (4) Freshwater snakes, living in or frequenting fresh waters they are excellent swimmers and divers. The nostrils are placed on the top of the snout and can be closed whilst the animal is under water. Their body is cylindrical, moderately long, provided with narrow ventral scutes ; the tail tapering; head flat, rather short; and the eyes of small size. They feed on fish, frogs, and other aquatic animals, and are innocuous and viviparous. (5) Sea snakes are distinguished by the compressed, rudder-shaped tail, supported by erect neural and haemal spines. They never leave the sea (with the exception of one genus) and are unable to move on land. They feed on fishes, are viviparous and poisonous.
The majority of snakes are active during the day, their energy increasing with the increasing temperature of the air; whilst some delight in the moist sweltering heat of dense tropical vegetation, others expose themselves to the fiercest rays of the midday sun. Not a few, however, lead a nocturnal life, and many of them have, accordingly, their pupil contracted into a vertical or more rarely a horizontal slit. Those which inhabit temperate latitudes hibernate. Snakes are the most stationary of all vertebrates; as long as a locality affords them a sufficiency of food and some shelter to which they can readily retreat, they have no inducement to change it. Their dispersal, therefore, must have been extremely slow and gradual.
Locomotion. Although able to move with extreme rapidity, they cannot maintain it for any length of time. Their organs of locomotion are the ribs, the number of which is very great, nearly corresponding to that of the vertebrae of the trunk. They can adapt their motions to every variation of the ground over which they move, yet all varieties of snake locomotion are founded on the following simple process. When a part of the body has found some projection of the ground which affords it a point of support, the ribs are drawn more closely together, on alternate sides, thereby producing alternate bends of the body. The hinder portion of the body being drawn after, some part of it (c) finds another support on the rough ground or a projection; and, the anterior bends being stretched in a straight line, the front part of the body is propelled (from a to d) in consequence. During this peculiar locomotion the numerous broad shields of the belly are of great advantage, as by means of their free edges the snake is enabled to catch and use as points of support the slightest projections of the ground. A pair of ribs corresponds to each of these ventral shields. Snakes are not able to move over a per-fectly smooth surface. Thus it is evident that they move by dragging their body over the ground, or over some other firm base, such as the branch of a tree; hence the conventional representation of the progress of a snake, in which its undulating body is figured as resting by a series of lower bends on the ground whilst the alternate bends are raised above it, is an impossible attitude. Also the notion that snakes when attacking are able to jump off the ground is quite erroneous; when they strike an object, they dart the fore part of their body, which was retracted in several bends, forwards in a straight line. And sometimes very active snakes, like the cobra, advance simultaneously with the remainder of the body, which, however, glides in the ordinary fashion over the ground; but no snake is able to impart such an impetus to the whole of the body, which, however, glides in the ordinary fashion over the ground; but no snake is able to impart such an impetus to the whole of its body as to lose its contact with the ground. Some snakes can raise the anterior part of their body and even move in this attitude, but it is only about the anterior fourth or third of the total length which can be thus erected.
Integuments. With very few exceptions, the integuments form imbricate scale-like folds arranged with the greatest regularity; they are small and pluriserial on the upper parts of the body and tail, large and uniserial on the abdomen, and generally biserial on the lower side of the tail. The folds can be stretched out, so that the skin is capable of a great degree of distension. The scales are sometimes rounded bebind, but generally rhombic in shape and more or less elongate; they may be quite smooth or provided with a longitudinal ridge or keel in the middle line. The integuments of the head are divided into non-imbricate shields or plates, symmetrically arranged, but not corresponding in size or shape with the underlying cranial bones or having any relation to them. The form and number of the scales and scutes, and the shape and arrangement of the headshields, are of great value in distinguishing the genera and species, and it will therefore be useful to explain in the accompanying woodcut (fig. 3) the terms by which these parts are designated. The skin does not form eyelids ; but the epidermis passes over the eye, forming a transparent disk, concave like the glass of a watch, behind which eye moves. It is the first part which is cast off when the snake sheds its skin; this is done several times in the year, and the epidermis comes off in a single piece.
Tongue. The tongue in snakes is narrow, almost worm-like, generally of a black colour and forked; that is, it terminates in front in two extremely fine filaments. It is often exserted with a rapid motion, sometimes with the object of feeling some object, sometimes under the influence of anger or fear.
Dentition. Snakes possess teeth in the maxillaries, mandibles, palatine, and pterygoid bones, sometimes also in the intermaxillary; they may be absent in one or the other of the bones mentioned. In the innocuous snakes the teeth are simple and uniform in structure, thin, sharp like needles, and bent backwards; their function consists merely in seizing and holding the prey. In some all the teeth are nearly of the same size; others possess in front of the jaws (Lycodonts) or behind in the maxillaries (Diacrasterians) a tooth more or less conspicuously larger than the rest; whilst others again are distinguished by this larger posterior tooth being grooved along its outer face. The snakes with this grooved kind of tooth have been named Opisthoglyphi, and also Suspecti, because some herpetologists were of opinion that the function of the groove of the tooth was to facilitate the introduction of poisonous saliva into a wound. The venomous nature of these snakes, however, has never been proved, and persons are frequently bitten by them without any evil consequences. Nevertheless as the depth of the groove, the length of the tooth, and the development of the salivary glands in its vicinity vary greatly, it is quite possible that the function and the physiological effect of this apparatus are not the same in all Opisthoglyphs. In the true poisonous snakes the maxillary dentition has undergone a special modification. The so-called Colubrine Venomous snakes, which retain in a great measure an external resemblance to the innocuous snakes, have the maxillary bone not at all, or but little, shortened, armed in front with a fixed, erect fang, and provided with a deep groove or closed canal for the conveyance of the poison, the fluid being secreted by a special poison-gland. One or more small ordinary teeth may be placed at some distance behind this poison-fang. In the other venomous snakes (Viperines and Crotalines) the maxillary bone is very short, and is armed with a single very long curved fang with a canal and aperture at each end. Although firmly anchylosed to the bone, the tooth, which when at rest is laid backwards, is erectile,the bone itself being mobile and rotated round its transverse axis by muscles. One or more reserve teeth, in various stages of development, lie between the folds of the gum and are ready to take the place of the one in function whenever it is lost by accident, or shed, which seems to happen at regular intervals. The gland which secretes the poison is described under REPTILES (vol. xx. p. 457).
Food. All snakes are carnivorous, and as a rule take living prey only; a few feed habitually or occasionally on eggs. Many swallow their victim alive ; others first kill it by smothering it between the coils of their body (constriction). The effects of a bite by a poisonous snake upon a small mammal or bird are almost instantaneous, preventing its escape; and the snake swallows its victim at its leisure, sometimes hours after it has been killed. The prey is always swallowed entire, and, as its girth generally much exceeds that of the snake, the progress of deglutition is very laborious and slow. Opening their jaws to their fullest extent, they seize the animal generally by the head, and pushing alternately the right and left sides of the jaws forward, they press the body through their elastic gullet into the stomach, its outlines being visible for some time through the distended walls of the abdomen. Digestion is quick and much accelerated by the quantity of saliva which is secreted during the progress of deglutition, and in venomous snakes probably also by the chemical action of the poison. The primary function of the poison apparatus in the economy of snakes is without doubt to serve as the means of procuring their food. But, like the weapons of other carnivorous animals, it has assumed the secondary function of an organ of defence. Only very few poisonous snakes (like Ophiophagus elaps) are known to resent the approach of man so much as to follow him on his retreat and to attack him. Others, as if conscious of their fearful power of inflicting injury, are much less inclined to avoid collision with man than innocuous kinds and are excited by the slightest provocation to use thal power in self-defence. They have thus become one of the greatest scourges to mankind, and Sir J. Fayrer [191-1] has demonstrated that in India alone annually some 20,000 human beings perish from snake-bites. Therefore it will not be out of place to add here a few words on snake-poison and on the best means (ineffectual though they be in numerous cases) of counteracting its deleterious effects.
Action of snake-poison. Chemistry has not yet succeeded in separating the active principle of snake-poison or in distinguishing between the secretions of different kinds of poisonous snakes ; in fact it seems to be identical in all, and probably not different from the poison of scorpions and many Hymenoptera. The physiological effects of all these poisons on warm-blooded Vertebrates are identical, and vary only in degree, the smallest quantities of the poison producing a local irritation, whilst in serious cases the whole mass of the blood is poisoned in the course of some seconds or minutes , producing paralysis of the nerve-centres. That there is some difference, however, in the action of the poisons upon the blood has been shown by Fayrer, who found that the poison of Viperine snakes invariably destroys its coagulability, whilst nothing of the kind is observed in animals which perished from the bite of a Colubrine Venomous snake. The same observer has also experimentally demonstrated that the blood of a poisoned warm-blooded animal assumes poisonous properties, and, when injected, kills like the poison itself, although the bodies of the animals may be eaten by man with impunity. On the other hand, he has proved that the opinion generally adopted since Redis time, viz., that snake-poison is efficacious only through direct injection into the blood, is fallacious, and that it is readily absorbed through mucous and serous membrances, producing the same effects, though in a midler degree.
Causes influencing snake-bites. The degree of danger arising from a snake-bite to man depends in the first place on the quantity of poison injected: a large vigorous snake which has not bitten for some time is more to be feared than one of small size or one which is weakly or has exhausted its stock of poison by previous bites. The bite of some of the smaller Australian Diemenias and Hoplocephali is followed by no worse consequences than those arising from the sting of a wasp or a hornet, while immediately fatal cases are on record of persons bitten by the cobra or the large South-American Crotalines. In the second place it depends on the strength of the individual bitten : a man of strong physical constitution and energetic mental disposition is better able to survive the immediate effects of the bite than a child or a person wanting in courage. Thirdly, it depends on the position and depth of the bite: the bite may be merely a superficial scratch, or may penetrate into tissue having few blood-vessels, and thus be almost harmless; or it may be deep in vascular tissue or even penetrate a vein, producing immediate and fatal effects. It must be mentioned also that Fayrer is distinctly of opinion that the poison of some kinds is more powerful than that of others. The mere shock produced by the bite of a snake upon a nervous person may be sufficiently severe to be followed by symptoms of collapse, although no actual poisoning of the blood has taken place, or although the bite was that of an innocuous snake. It is said that persons have actually died under such circumstances from mere fright. The local appearances in the neighbourhood of a poisoned wound, which soon after the bite is much swollen and discoloured and very painful, readily prove its character ; but this can be often ascertained also immediately after the bite by the inspection of the wound,the teeth, which are so differently arranged in poisonous and non-poisonous snakes, leaving a different pattern on the skin. As a non-poisonous snake has four rows of teeth in the upper jaw, the pattern of its bite will more or less resemble fig 4, whilst a poisonous snake leaves two rows of more distinctly marked punctured wounds in the place of the two outer series in the non-poisonous (see fig. 5). Of course, there may be modifications of these patterns, as, for instance, when one fang only hits or penetrates the part aimed at, or when the direction of the stroke is slanting, producing merely a scratch.
Remedies and treatment. Unfortunately no antidote is known capable of counteracting or neutralizing the action of snake-poison. Some years ago injections of ammonia or liquor potassae were recommended, but there is the obvious objection that hardly in one out of a thousand cases of snake-bite would either the appliances or the operator be at hand. Fayrers experiments, however, have distinctly disproved the efficacy of this remedial measure. Equally useless is permanganate of potassium; it is indeed true that a solution of this compound destroys the properties of snake-poison when mixed with it ; and therefore such of the poison as remains in the wound will be neutralized by the external application or injection of the permanganate, but the remedy is entirely without effect after the poison has passed into the circulation. Treatment is therefore limited to endeavours to prevent by mechanical means the poison from entering the circulation, or by chemical agencies to destroy or remove as much of it as possible that remains in the wound, and to save the patient from the subsequent mental and physical depression by the free use of stimulants. Whatever is or can be done must be done immediately, as a few seconds suffice to carry the poison into the whole vascular system, and the slightest delay diminishes the chances of the patients recovery. Courageous persons badly bitten in a finger or toe are known to have saved saved their lives by the immediate amputation of the wounded member. To the mode of treatment summarized by Günther [191-2] but little can be added. (1) If the wound is on some part of the extremities, one or more ligatures should be made as tightly as possible at a short distance above the, wound, to stop circulation ; this is most effectually done by inserting a stick under the ligature and twisting it to the uttermost. The ligatures are left until means are taken to destroy the virus in the wound and other remedial measures are resorted to, or until the swelling necessitates their removal. (2) The punctured wounds should be enlarged by deep incisions, to cause a free efflux of the poisoned blood, or should be cut out entirely. (3) The wound should be sucked either by the patient or some other person whose mouth is free from any solution of continuity. Cupping-glasses, where they can be applied, answer the same purpose, but not with the same effect. (4) by cauterization with a red-hot iron a live coal, nitrate of silver or carbolic or mineral acid, or by injections of permanganate of potassium, the poison which remains in the wound can be destroyed or neutralized. Ammonia applied to the wound as a wash and rubbed into the neighbouring parts is likewise undeniably of great benefit, especially in less serious cases, since it alleviates the pain and reduces the swelling. (5) Internally, stimulants are to be taken freely ; they do not act as specifies against the virus, but are given to excite the action of the heart, the contractions of which become feeble and irregular, to counteract the physical and mental depression, and to prevent a complete collapse. Brandy, whisky, and ammonia in any of its officinal forms should be taken in large doses and at short intervals. The so-called "snake-stones" can have no other effect than, at the best, to act as local absorbents, and can be of use only in the very slightest cases.
Propagation. Snakes are oviparous; they deposit from ten to eighty eggs of an ellipsoid shape, covered with a soft leathery shell, in places where they are exposed to and hatched by moist heat. The parents pay no further attention to them, except the pythons, which incubate their eggs by coiling their body over them, and fiercely defend them. In some families, as many freshwater snakes, the sea snakes, Viperidae, and Crotalidae, the eggs are retained in the oviduct until the embryo is fully developed. These snakes bring forth living young, and are called "ovo-viviparous."
Classification. The order of snakes may be divided into the following sub-orders and families or groups.
Small burrowing snakes, with a cylindrical body, which is nearly of the same thickness from its anterior to its posterior extremity, and is covered with smooth polished scales of the same size in its whole circumference. No mental groove. Head small, not distinct from the trunk, with imbricate scale-like scutes. Eye rudimentary. Mouth very narrow, at the lower side of the head, armed with small teeth in one jaw only.
Family 1. TYPHLOPIDAE.Teeth in the upper jaw only.
Genera: Typhlina, Onychocephalus, Typhlops (see figs. 6, 7).
Family 2. STENOSTOMATIDAE.Teeth in the lower jaw only.
Genera: Stenostoma, Siagnodon.
Second Sub-order.Ophidii Colubriformes.
Innocuous snakes. Teeth in both jaws, none of the anterior being grooved or perforated. Scales more or less differentiated. A mental groove is generally present. Eye developed.
Family 1. TORTRICIDAE.Body cylindrical, with a rounded head not distinct from the neck ; tail very short. Rudiments of hind limbs hidden in a small groove on each side of the vent. Scales rounded, polished, those of the ventral series but little enlarged; only one pair of frontals ; six upper labials. Eye small. Mouth of moderate width; teeth few in number, sub-equal in size.
Genera: Ilysia (tropical America); Cylindrophis (India).
Family 2. XENOPELTIDAE.Body cylindrical, with a rounded head not distinct from the neck; tail short. No rudimentary hind limbs. Scales rounded, polished; ventral shields well differentiated; two pairs of frontals ; occiput covered with five shields. Eye small. Mouth of moderate width ; teeth numerous, sub-equal.
One genus, from the Indian region : Xenopeltis.
Family 3. UROPELTIDAE (Rough Tails).Body cylindrical, with a short head not distinct from the neck ; tail very short, truncated or scarcely tapering, frequently terminating in a rough naked disk or covered with keeled scales. Scales rounded and polished, those of the ventral series being always somewhat larger than the rest ; only one pair of frontals ; four upper labials. Eye very small. Mouth of moderate width ; teeth few in number, small, sub-equal, none on the palate. Mental groove generally absent. Small burrowing Indian snakes.
Genera: Rhinophis, Uropeltis, Silybura, Plectrurus, Melanophidium.
Family 4. CALAMARIDAE.Small snakes, with a rather rigid body; the short head not distinct from the neck; tail more or less short. Scales in from thirteen to seventeen series; ventral shields well developed, generally less than 200 in number; the normal number of head-shields always reduced by two or more of them being confluent. Cleft of the mouth of moderate width; nostril lateral; palatine teeth present.
African genera: Homalosoma, Calamelaps, Prosymna, Opisthotropis, Xenocalamus, Amblyodipsas, Elapops, Urobelus, Uriechis. Europeo-Asiatic genera: Rhynchocalamus, Psilosoma. Indian genera: Calamaria, Macrocalamus, Typhlogeophis, Xylophis, Oxycalamus, Brachyorrhos, Elapoides, Rhinosimus, Aspidura, Haplocercus, Achalinus (Japan). North-American genera: Carphophis, Conocephalus, Streptophorus, Contia. Tropical American genera: Homalocranium, Arrhyton, Rhegnops, Colobognathus, Geophidium, Catostoma, Stenognathus, Leptocalamus, Chersodromus, Elapomorphus, Cercocalamus, Microdromus, Stenorhina, Rhinostoma, Rhynchonyx. Genus with wide distribution: Geophis.
Family 5. OLIGODONTIRAE.Body rather rigid, covered with smooth rounded scales; head short, not distinct from neck, and nearly always with symmetrical arrow-shaped markings above. Ventral scutes broad; rostral shield large, more or less produced backwards. Maxillary teeth few in number, the hindmost enlarged, not grooved. Indian.
Genera: Oligodon, Simotes.
Family 6. COLUBRIDAE.This family comprises the majority of the non-venomous snakes and the least specialized forms. Their body of moderate length compared to its circumference, flexible in every part; the head, trunk, and tailin fact all partswell proportioned; nostril lateral; teeth numerous in the jaws and on the palate, but without fangs in front or in the middle of the maxillary. Double row of sub-caudals. This family may be divided in accordance with the general habitus or mode of life into several groups, which, however, are connected by numerous intermediate forms.
The group of (i.) Ground Colubrides, Coronellina, consists of small forms, generally of brilliant coloration, and comprises the following genera:
Genera with wide distribution: Ablabes, Cyclophis, Tachymenis, Coronella, Liophis. African: Psammophylax, Ditypophis. Indian: Megablabes, Nymphophidium, Odontomus. Tropical American: Erythrolamprus, Pliocercus, Hypsirhynchus.
The group of (ii.) True Colubrides, Colubrina, are land snakes, which swim well when driven into the water, or climb when in search of food ; they are of moderate or rather large size.
Genera with wide distribution: Coluber, Elaphis, Plyas, Zamenis. African genera: Xenurophis, Herpetaethiops, Scaphiophis. Indian genera: Compsosoma, Xenelaphis, Cynophis, Lielaphis, Lytorhynchus. Europeo-Asiatic: Rhinechis. North-American: Pituophis. South-American: Spilotes. Australian: Zamenophis.
The group of (iii.) Bush Colubrides, Dryadina, lead up to the true Tree snakes, its members having a more or less elongate and compressed body, frequently of green colour; they are more numerous in the New than in the Old World, and belong to the following
Genera: Dromicus, Herpetodryas, Herpetoreas, Philodryas, Diplotropis, Zaocys, Dryocalamus.
Finally, the group of (iv.) Freshwater Colubrides, Natricina, are generally neither elongate nor compressed, and possess frequently keeled scales. They freely enter water in pursuit of their prey,chiefly frogs and fishes.
Genera with wide distribution: Tropidonotus, Heterodon. African: Grayia, Neusterophis, Limnophis, Hydraethiops, Macrophis. Indian: Xenochrophis, Prymnomiodon, Atretium. North-American: Ischnognathus. South-American: Xenodon, Tomodon.
Family 7. HOMALOPSIDAE (Freshwater Snakes).Body of moderate length, cylindrical or slightly compressed ; head rather thick, broad, not very distinct from neck; tail strong, of moderate length. Ventral scutes rather narrow; double row of sub-caudals. Eye small. Nostrils on the upper surface of the head, small, provided with a valve; nasal shields enlarged at the expense of the anterior frontals, which are frequently confluent into a single shield. The other head shields may deviate from the usual arrangement.
Indian genera: Fordonia, Cantoria, Cerberus, Hypsirhina, Ferania, Homalopsis, Hipistes, Herpeton (see fig. 8), Gerrarda, Tachyplotus. American genera: Calopisma, Helicops, Hydrops, Tachynectes, Hydromorphus.
Family 8. PSAMMOPHIDAE (Desert Snakes).Loreal region very concave. Scales smooth ; double row of sub-caudals. Cleft of the mouth wide; nostril lateral. Eye of moderate size. Shields of the head normal; posterior frontals rounded or angular behind ; vertical narrow; supraciliaries prominent. Loreal present. One of the four or five anterior maxillary teeth longer than the others, and the last grooved. Old World.
Genera: Psammophis, Coelopeltis, Taphrometopon, Rhagerrhis, Psammodynastes, Mimophis.
Family 9. RHACHIODONTIDAE (Egg-Eaters).Body of moderate dimensions ; head short, deep. Eyes small, pupil round. Scales strongly keeled, in twenty-three or twenty-five series. Maxillary teeth very small and few in number; the lower spinous processes of the posterior cervical vertebrae penetrate the aesophagus and act as supplementary teeth. African.
One genus: Dasypeltis (see fig. 9).
Family 10. DENDROPHIDAE (Tree Snakes).Body and tail much compressed or very slender and elongate ; head generally elongate and distinct from the very slender neck ; snout rather long, obtuse or rounded in front. Cleft of the mouth wide. Eye of moderate size or large, with round pupil. Shields of the head normal ; scales generally narrow and much imbricate ; ventral sentes keeled laterally; double row of sub-caudals. No large fang either in front or in the middle of the upper jaw.
African genera: Bucephalus, Hapsidophrys, Rhamnophis, Philothamnus, Ithycyphus. Indian and Australian genera: Gonyosoma, Phyllophis, Dendrophis, Chrysopelea. Tropical American: Ahaetulla.
Family 11. DRYOPHIRAE (Whip Snakes).Body and tail excessively slender and elongate; head very narrow and long with tapering snout, which sometimes is produced into a longer or shorter appendage. Mouth very wide. Eye of moderate size, generally with a horizontal pupil. Scales very narrow, much imbricate ; double row of sub-caudals. Posterior maxillary teeth grooved.
Genera: Tropidococcyx, Cladophis, Dryophis, Tragops, Passerita (see fig. 10), Langaha.
Family 12. DIPSADIDAE.Body much compressed, elongate or of moderate length ; head short, broad behind, with short rounded snout distinct from neck. Eye large, generally with vertical pupil. Cleft of the mouth wide. Scales of the vertebral series frequently enlarged. Dentition strong, frequently with enlarged anterior and posterior maxillary teeth.
Genera: Chamaetortus, Leptodira, Tropidodipsas, Hemidipsas, Thamnodynastes, Dipsas, Dipsadoboa, Rhinobothryum, Pythonodipsas.
Family 13. SCYTALIDAE.Head, trunk, and tail of moderate dimensions. Eye of moderate size, with elliptical pupil. Scales smooth, in seventeen or nineteen rows; anal entire; single or double row of sub-caudals. Posterior maxillary teeth grooved, anterior ones equal in length.
Genera: Scytale, Oxyrhopus, Hologerrhum, Pseudoxyrhopus, Rhinosimus.
Family 14. LYCODONTIDAE. Body of moderate length or rather elongate; snout generally depressed, flat, and elongate. Eye rather small, often with vertical pupil. Upper head-shields regular, with the posterior frontals enlarged. Maxillary with a fang in front, but without posterior grooved tooth.
African genera: Boodon, Holuropholis, Alopecion, Lycophidium, Bothrophthalmus, Bothrolycus, Lycodryas, Hormonotus, Simocephalus, Lamprophis. Indian genera: Lycodon, Dinodon, Tetragonosoma, Leptorhytaon, Ophites, Cercaspis, Ulupe.
Family 15. AMBLYCEPHALIDAE (Blunt Heads).Body compressed, slender, and of moderate length; head short, thick, very distinct from neck; nostril in a single shield. Eye with vertical pupil. Cleft of the mouth narrow and not very extensible. Scales smooth or faintly keeled, those of the vertebral series generally enlarged. Maxillary dentition feeble, no grooved tooth.
Indian genera: Dipsadomorus, Amblycephalus, Pareas, Asthenodipsas, Elachistodon. South-American genera: Leptognathus, Opisthophis.
Family 16. ERYCIDAE (Sand Snakes)Body of moderate length, cylindrical, covered with small short scales; tail very short, with a single series of sub-caudals. Eye small, with vertical pupil. None of the labials are pitted. Anterior teeth longest. Adult individuals of some of the species with rudiments of hind limbs.
Genera: Eryx, Cursoria, Gongylophis, Bolyeria, Erebophis, Lichanura, Calabaria, Wenona, Charina.
Family 17. BOIDAE.Body and tail of moderate length or elongate; tail prehensile; snout rounded in front. Eye with vertical pupil. Scales in numerous series; single or double row of subcaudals. In some of the genera the upper and lower labials are pitted. Teeth strong, unequal in size, none grooved; no intermaxillary teeth. Rudiments of hind limbs are generally present.
Genera: Boa (see fig. 11), Pelophilus, Xiphosoma, Corallus, Epicrates, Chilabothrius, Enygrus, Leptoboa, Ungalia, Trachyboa.
Family 18. PYTHONIDAE (Rock Snakes).Distinguished from the preceding family by the presence of intermaxillary teeth.
Genera: Python (see fig. 12), Morelia, Chondropython, Liasis, Aspidiotes, Nardoa, Loxocemus.
Family 19. ACROCHORDIDAE (Wart Snakes).Body of moderate length, covered with small, non-imbricate, tubercular or spiny scales; tail rather short, prehensile. Head covered with scales like the body ; nostrils close together, at the top of the snout. Eye small. Teeth short, strong, sub-equal in size. Aquatic. Viviparous. India.
Genera: Acrochordus, Chersydrus.
Family 20. XENODERMIDAE.Distinguisbed from the preceding family by possessing broad ventral and sub-caudal scutes.
One genus: Xenodermus (Java). ? Nothopsis (Central America).
Third Sub-order.Ophidii Colubriformes Venenosi.
Venomous Colubrine snakes. An erect grooved or perforated tooth in front of the maxillary which is not capable of rotation in its transverse axis. Scales differentiated. A mental groove.
Family 1. ELAPIDAE.Tail conical, tapering. Head with shield: loreal absent. Venom-fang grooved; maxillary long, with short teeth behind the fang.
Genus with wide distribution: Naja (see fig. 13). Indian genera: Callophis, Megaerophis, Hemibungarus, Xenurelaps, Bungarus, Ophiophagus. African genera: Poecilophis, Elapsoidea, Cyrtophis. South-American genus: Elaps (see fig. 14). Australian genera: Vermicella, Brachysoma, Neelaps, Brachyurophis, Rhinelaps, Diemenia, Cacophis, Hoplocephalus, Tropidechis, Pseudechis, Pseudonaja, Pseudohaje, Ogmodon.
Family 2. ATRACTASPIDIDAE.Body cylindrical, of moderate proportions; tail short. Head short, not distinct from neck. Mouth narrow. Maxillary short, with perforated poison-fang, without other teeth behind. Africa.
Family 3. CAUSIDAE.Body of moderate proportions, tail moderate or rather short. Head distinct from neck. Mouth wide. Maxillary short, with perforated poison-fang, without other teeth behind.
African genera: Sepedon, Causus. South-American: Dinodipsas.
Family 4. DINOPHIDAE (Venomous Tree Snakes).Body and tail much elongate; head distinct from neck. Mouth wide. A perforated poison-fang, without other teeth behind. Africa.
Genus: Dinophis (Dandraspis).
Family 5. HYDROPHIDAE (Sea Snakes).Body generally compressed, and without broad ventral scutes; tail compressed, rudder-shaped. Nostrils directed upwards. Poison-fangs small, grooved. Viviparous.
Genera: Platurus, Aipysurus, Disteira, Acalyptus, Hydrophis, Enhydrina, Pelagophis, Pelamis (see fig. 15).
Fourth Sub-order.Ophidii Viperiformes.
Viperine snakes. Maxillary very short, capable of rotation in its transverse axis, and armed with a single long tooth, which is perforated. Viviparous.
Family 1. VIPERIDAE (Vipers). Loreal region flat, without pit.
Old World genera: Vipera, Cerastes, Daboia, Echis (see fig. 17), Atheris. Australian: Acanthophis.
Family 2. CROTALIDAE (Pit Vipers, Rattlesnakes).Loreal region with a pit.
Old World genera: Halys, Hypnale, Trimeresurus (see fig. 18), Calloselasma, Peltopelor. New World genera: Cenchris, Bothrops, Bothriopsis, Bothriechis (Rhinocerophis), Atropos, Trigonocephalus, Lachesis, Crotalophorus, Crotalus (see fig. 16).
This list, from which many genera or sub-genera that are not well defined have been excluded, will give an idea of the great variety of forms by which the Ophidian type is represented at the present period. Additions, more or less numerous, are made to it every year; but the discoveries of late years have not revealed any new important modifications of structure, but rather have undermined the distinctions hitherto made between genera, groups, and families, so that it would appear as if we were acquainted with all the principal forms of snakes now living.
Burrowing snakes. We have now to add some notes on snakes to which special interest is attached, or which are most frequently brought to the notice of the observer or reader. The snakes most remote from the true Ophidian type are the members of the first family, Typhlopidae. They are a small degraded form, adapted for burrowing and leading a subterranean life like worms. Their body is cylindrical, rigid, covered with smooth, short, highly polished, and closely fitting scales, without broad ventral scutes; tail very short; head joined to the trunk without neck-like constriction behind, and short, rounded, or with an acute rostral shieldthe principal instrument for burrowing in loose soil or mould. Their eye is quite rudimentary and can only give them a general perception of light. Their mouth is narrow, small, armed with but a few teeth in one of the jaws, and not distensible, allowing them only to feed on very small animals, such as worms, larvae, and burrowing insects. They are found in all tropical countries and the parts adjoining, and some of the small species have a wide range, having been probably transported by accident on floating objects to distant countries. Some species attain to a length of 24 inches, whilst others scarcely grow to one-fourth that size.
An almost unbroken series leads from these degraded worm-like snakes to the typical Colubridae, of which the Smooth Snake of Europe (Coronella), the Corn Snake of North America (Coluber), the Rat Snake of India and South America (Ptyas, Spilotes), Aesculapiuss Snake of the south of Europe, the common Ring Snake of England (Tropidonotus), are well-known representatives.
Smooth Snake. The Smooth Snake (Coronella laevis) is common in the warmer parts of Europe, extending northwards into the New Forest district of England. In coloration, general habits, and size it somewhat resembles the viper; but, although it is rather fierce and ready to bite when caught, it is quite harmless and soon becomes tame in captivity. The shields on its head readily distinguish it from the viper. Its chief food consists of lizards, and it attains a length of 2 feet.
Indian rat snakes. The Indian Rat Snakes (Ptyas mucosus and P. korros) are two of the most common species of India, the former inhabiting India proper and Ceylon, the latter the East Indian Archipelago, Siam, and southern China. P. mucosus is a powerful snake, attaining to a length of 7 feet, the tail being one-third or rather more ; it is easily recognized by having three loreal shields, one above the other two; its scales are arranged in seventeen rows. Its food consists of mammals, birds, and frogs; and it frequently enters the dwellings of man, rendering itself useful by clearing them of rats and mice. It is of fierce habits, always ready to bite; when irritated it utters a peculiar diminuendo sound, not unlike that produced by a tuning-fork when struck gently.
Aesculapiuss snake. Aesculapiuss Snake (Coluber aesculapii) was probably the species held in veneration by the ancient Romans. It grows to a length of about 5 feet, is of mild disposition, and can be readily domesticated. Its original home is Italy, where it is common, but it has extended its range northwards across the Alps into the south of France, and thence into northern Spain. Following the course of the Inn and the Danube, it has reached the Black Sea; and it is also now common in several localities along the middle parts of the Rhine. From direct observations made during the last twenty years there can be no doubt that it is still extending its range. Naturalists believed formerly that the occurrence of this snake at widely distant and isolated localities was due to its introduction by the Romans, who had settlements in those localities.
British ring snake.The common British Snake or Ring Snake (Tropidonotus natrix) is extremely common all over Europe (except in the northern parts), and belongs to a genus extremely rich in species, which are spread over Europe, Asia, India, Australia, and North America. Some of the species, like the Indian T. quincunciatus and T. stolatus and the North-American T. ordinatus, are perhaps more abundant as regards the number of individuals than any other snake. T. natrix is easily recognized even at a distance by two yellow or white spots which it has behind its head. It grows rarely to a length of 4 feet; it never bites, and feeds chiefly on frogs and toads. Its eggs, which are of the size and shape of a doves egg, and from fifteen to thirty in number, are deposited in mould or under damp leaves, and are glued together into one mass.
Egg eaters. A very peculiar genus of snakes, Dasypeltis, represented by three species only, is the type of a separate family and is restricted in its distribution to Central and South Africa. In Cape Colony these snakes are well known under the name of "eyervreter," i.e., "egg-eaters." Their principal diet seems to consist of eggs, their mouth and oesophagus being so distensible that an individual scarcely 20 inches in length, and with a body not surpassing a mans little finger in circumference, is able to swallow a hens egg. The teeth in the jaws are very small and few in number; but the inferior processes of the posterior cervical vertebrae are prolonged and provided with a cap of enamel, and penetrate the oesophagus, forming a kind of saw. As the egg passes through the oesophagus its shell is broken by this apparatus, and, whilst its contents are thus retained and swallowed without loss, the hard fragments of the shell are rejected. This peculiar apparatus occurs also in another snake, Elachistodon, which belongs to the Indian fauna and has been referred (provisionally) to the family Amblycephalidae. Also two prominences at the base of the skull of the Indian Coronelline Nymphophidium probably have the same function. Besides the snakes mentioned, we have observed species of Dipsas feeding on eggs of parrots, the eggs reaching the stomach entire, as these snakes lack a special apparatus for breaking the shell. The Indian cobra also is said to rob birds of their eggs.
Tree snakes. The Tree Snakes (Dendrophidae) are among the greatest ornaments of tropical fauna. The graceful form of their body, the elegance and rapidity of their movements, and the exquisite beauty of their colours have been the admiration of all who have had the good fortune to watch them in their native haunts. The majority lead an exclusively arboreal life; only a few descend to the ground in search of their food. They prey upon every kind of arboreal animal,birds, tree-frogs, tree-lizards, &c. All seem to be diurnal, and the larger kinds attain to a length of about 4 feet. The most beautiful of all snakes are perhaps certain varieties of Chrysopelea ornata, a species extremely common in the Indian Archipelago and many parts of the continent of tropical Asia. One of these varieties is black, with a yellow spot in the centre of each scale; these spots are larger on the back, forming a series of tetrapetalous flowers; the head is similarly ornamented. Another variety has a red back, with pairs of black cross-bars, the bands of each pair being separated by a narrow yellow space; sides brown, dotted with black; belly dark green, the outer portion of each ventral shield being yellow, with a blackish spot.
Whip snakes. The features by which the tree snakes are distinguished are still more developed in the family of Whip Snakes (Dryophidae), whose excessively slender body has been compared to the cord of a whip. Although arboreal, like the former, they are nocturnal in their habits, having a horizontal instead of a round pupil of the eye. They are said to be of a fierce disposition, feeding chiefly on birds; and indeed a long tooth placed about the middle of the maxillary seems to assist them much in penetrating the thick covering of feathers and in obtaining a firm hold on their victims. In some of the species the elongate form of the head is still more exaggerated by a pointed flexible appendage of the snout (Passerita), which may be nearly half an inch in length, and leaf-like, as in the Madagascar Langaha.
Lycodontidae. The well-defined family of Lycodontidae is chiefly composed of ground snakes, but a few of its members have a sufficiently elongate body to indicate arboreal habits. The Indian genera are principally reptilivorous, while the African prey upon mice, rats, and other small nocturnal mammals. Scarcely any other snake is so common in collections as the Indian Lycodon aulicus, which inhabits the continent of India and Ceylon, some of the islands of the East Indian Archipelago (Timor), and the Philippines. It occurs in many varieties, but generally is of a uniform brown, or with some whitish crossbands on the anterior part of the body. Although only 2 feet long, it is a fierce snake, which when surprised bites readily, but its bite, is innocuous.
Boas. The Boidae are so similar in their habits to the Pythons (see PYTHON, vol. xx. p. 144) that it is sufficient to refer in a few words to the species most frequently mentioned in the literature dealing with the fauna of the virgin forests of tropical America. The real Boa constrictor is common from the northern parts of Central America to southern Brazil, and is frequently brought alive to Europe. Generally it is only about 7 feet long; but the present writer has seen skins of specimens which must have been nearly twice that length. The gigantic snakes of from 20 to 30 feet in length mentioned in books of South-American travels belong to a different species, the Anaconda or B. murina, which has the same habits as the B. constrictor, haunting the banks of rivers and lakes and lying in wait for peccaries, deer, and other mammals of similar size, which come to the water to drink. It has already been stated (see REPTILES) that this family is not restricted to South America, but is well represented in the tropical Pacific region. The Boid most common in that region is Enygrus, which ranges all over New Guinea, the Fiji Islands, the Solomon group, Samoa, and many other Pacific islands; it is of small size, scarcely 30 inches long.
We pass now to the Venomous Colubrine snakes, that is, snakes which combine with the possession of a perfect poison apparatus the scutellation and general appearance of the typical non-poisonous snakes. It is a remarkable fact, however, that the snakes of this sub-order agree in the absence of the small shield on the side of the snout, the so-called "loreal"; and this is all the more remarkable as the same shield has by no means a similar taxonomic significance in the non-venomous snakes, many of which are without it, although it is present in the majority.
Cobras. No snake of this sub-order is more widely known and more dreaded than the species of the genus Naja or cobras. Probably more than two species should be distinguished; but the two which cause the greatest loss of life are the Indian Cobra or Cobra di Capello or Naga (N. tripudians) and the African Cobra (N. haje). In a report to the Bengal Government the commissioner of Burdwan states that he has ascertained from statistics collected during a series of nine years that above 1000 persons are killed annually by snakes in a population of nearly 6,000,000, the majority being bitten by the cobra, which is by far the most common. And other districts in India seem to suffer still more severely, although it is difficult to obtain information of all the accidents caused by snakes. The cobra is found throughout India, extending westwards to the Sutlej and eastwards to the Chinese island of Chusan; in the Himalayan alps it reaches an altitude of 8000 feet; it occurs also in abundance in many of the islands of the East Indian Archipelago, and is here joined by another apparently distinct species (N. sputatrix), whilst in the central portions of Asia, which geographically separate it from the African cobra, it is replaced by a fourth, N. oxiana. The Indian cobra appears in many varieties of colour, which are distinguished by separate names in the nomenclature of the Hindu snake-charmers. The ground colour varies from a yellowish olive to brown and to black with or without whitish or white crossbands on the back, and with from one to four or without any black bars across the anterior part of the belly. Some of these varieties are characterized by a pair of very conspicuous white, black-edged spectacle-like marks on the expansible portion of the neck, called the "hood"; but these marks may lose their typical form and become merely a pair of ocellated spots, or be confluent into a single ocellus, or may be absent altogether. All these varieties, however, are the same species, which generally attains to a length of 5 feet, but sometimes exceeds 6. It is more of nocturnal than of diurnal habits, feeding on every kind of small Vertebrates and also eating eggs. The cobra and the other species of this genus have the anterior ribs elongated, and can move them so as to form a right angle with the spine. The effect of this movement is the dilatation of that part behind the head which is generally ornamented with the spectacles or ocelli. When the cobra is irritated or excited it spreads its "hood," raising the anterior third of the body from the ground, gliding along with the posterior two-thirds, and holding itself ready to strike forwards or sidewards. All accounts agree that the cobra is not ao, ressive unless interfered with or impelled by a sense of ag danger. It is said to share the habitations of man where superstition prevents people from molesting it, and to live peaceably with the inmates; and there is no doubt that professional snake-charmers exercise a certain control over them, for, although generally the cobras exhibited are rendered harmless by the removal of the poison-fangs, they very rarely attempt to injure their masters even after the fangs have been reproduced. Of the natural enemies of the cobra, the mongoos (see vol. xii. p. 629) does probably the greatest amount of execution; many are destroyed by fowls shortly after being hatched. The cobra is oviparous, depositing from eighteen to twenty-five eggs in the year. The African cobra is extremely similar to its Indian congener in size, form, and habits, and varies in coloration to the same extent. It inhabits the whole of Africa, from Egypt to the Cape of Good Hope, but has been nearly exterminated in the cultivated districts of the Cape Colony. One of its greatest enemies (as indeed of all snakes) is the secretary bird of South Africa (Serpentarius), which, therefore, is protected by law. Accidents from this snake do not appear to be of common occurrence; they happen more frequently to domestic animals than to man. In the Egyptian hieroglyphics the cobra occurs constantly with the body erect and hood expanded; its name was ouro, which signifies "king," and the animal appears in Greek literature as ouraios and basiliscus. With the Egyptian snake-charmers of the present day the cobra is as great a favourite as with their Hindu colleagues. They pretend to change the snake into a rod, and Geoffrey St-Hilaire maintains that the supple snake is made stiff and rigid by a strong pressure upon its neck, and that the animal does not seem to suffer from this operation, but soon recovers from the cataleptic fit into which it has been temporarily thrown.
Ophiophagus elaps. More dangerous than either of the species of cobra, which it exceeds in size, is Hamadryas or Ophiophagus elaps, the largest poisonous snake of the Old World, attaining to a length of 14 feet. It has almost the same geographical range as the cobra, but is much scarcer; it greatly resembles it also in general habit, but differs from it in scutellation, possessing three large shields behind the occipitals. It has the reputation of occasionally attacking and pursuing man; its favourite food consists of other snakes. Snake-charmers prize it highly for exhibition on account of its size and its docility in captivity, but are always careful to extract the fangs. It lives in captivity for many years.
Bungarums. The species of Bungarus, four in number, are extremely common in India, Burmah, and Ceylon, and are distinguished by having only one row of undivided sub-caudal shields. Three of the species have the body ornamented with black rings, but the fourth and most common (B. coeruleus), the "krait" of Bengal, possesses a dull and more uniform coloration. The fangs of the bungarums are shorter than those of the cobras, and cannot penetrate so deeply into the wound. Their bite is therefore less dangerous and the effect on the general system slower, so that there is more prospect of recovery by treatment. Nevertheless, according to Fayrer, the krait is probably, next to the cobra, the most destructive snake to human life in India.
Narrow-mouthed species. Several genera of this sub-order of Venomous Colubrines are similar to the innocuous Calamariidae in general habit; that is, their body is of a uniform cylindrical shape, terminating in a short tail, and covered with short polished scales; their head is short, the mouth rather narrow, and the eye small. They are the tropical American Elaps, the Indian Callophis, the African Poecilophis, and the Australian Vermicella. The majority are distinguished by the beautiful arrangement of their bright and highly ornamental colours; many species of Elaps have the pattern of the so-called coral snakes, their body being encircled by black, red, and yellow rings,a pattern which is peculiar to snakes, venomous as well as non-venomous, of the fauna of tropical America. Although the poison of these narrow mouthed snakes is probably as virulent as that of the preceding, man has much less to fear from them, as they bite only under great provocation. Moreover, their bite must be frequently without serious effect, owing to their narrow mouth and the small size of their poison-fangs. They are also comparatively of small size, only a few species rarely exceeding a length of 3 feet.
Australian poisonous colubrine snakes. No part of the world possesses so many snakes of this sub-order as Australia, where, in fact, they replace the non-venomous Colubrine snakes. Of the genus Diemenia six species, of Pseudechis three, and of Hoplocephalus some twenty species have been described, and many of them are extremely common and spread over a considerable area. Fortunately the majority are of small size, and their bites are not followed by more severe effects than those from the sting of a hornet, especially if the simple measures of sucking or cauterizing the wound are resorted to. Only the following are dangerous to man and larger animals:the Brown Snake (Diemenia superciliosa), found all over Australia and attaining to a length of over 5 feet; the Black Snake (Pseudechis porphyriacus), likewise common throughout the Australian continent, especially in low marshy places, and upwards of 6 feet in length ; it is black, with each scale of the outer series red at the base; when irritated it raises the fore part of its body and flattens out its neck like a cobra; the Brown-banded Snake (Hoplocephalus curtus), with a similar distribution, and also common in Tasmania, from 5 to 6 feet long, and considered the most dangerous of the tribe. [197-1]
African Causidae. The small family Causidae contains two African genera well known to and much feared by the inhabitants of South Africa. One, Sepedon haemachates, is named by the Boers "roode koper kapel" or "Ring-Neck Snake," the latter name being, however, often applied also to the cobra. It resembles in colour some varieties of the latter snake, and, like this, it has the power, though in a less degree, of expanding its hood. But its scales are keeled and its form is more robust. It is equally active and courageous, not rarely attacking persons who approach too near to its resting-place. In confinement it evinces great ferocity, opening its mouth and erecting its fangs, from which the poison is seen to flow in drops. During such periods of excitement it is even able, by the pressure of the muscles on the poison-duct, to eject the fluid to some distance; hence it shares with the cobra a third Dutch name, that of "spuw slang" (Spitting Snake). It grows to a length of 2 or 3 feet. The second African snake of this family is the "schapsticker" (Sheep Stinger), Causus rhombeatus. It is extremely common in South Africa and extends far northwards along the eastern as well as western coast. It is of smaller size than the preceding and causes more injury to animals, such as sheep, dogs, &c., than to man. It varies in colour, but a black mark on the head like an inverted V remains nearly always visible.
The Dinophidae are the arboreal type of this sub-order; they resemble non-venomous tree snakes in their gracile form, narrow scales, generally green coloration, and in their habits; nevertheless the perfect development of their poison-apparatus, their wide mouth, their large size (they grow to a length of 7 feet), leave no doubt that they are most dangerous snakes. They do not appear to be common, but are spread over all districts of tropical Africa in which vegetation flourishes.
Sea snakes. Of Sea Snakes (Hydrophidae) some fifty species are known. All are inhabitants of the tropical Indo-Pacific ocean, and most numerous in and about the Persian Gulf, in the East Indian Archipelago, and in the seas between southern China and northern Australia. One species which is extremely common (Pelamis bicolor), and which is easily recognized by the black colour of its upper and the yellowish tints of its lower parts (both colours being sharply defined), has extended its range westwards to the sea round Madagascar, and eastwards to the Gulf of Panama. Sea snakes are viviparous and pass their whole life in the water; they soon die when brought on shore. The most striking feature in their organization is their elevated and compressed tail. The hind part of the body is compressed, and the belly forms a more or less sharp ridge. The ventral shields would be of no use to snakes moving through a fluid, and therefore they are either only rudimentary or entirely absent. The genus Platurus, however, is a most remarkable exception in having broad ventral shields; probably these serpents frequently go on shore, sporting or hunting over marshy ground. In many sea snakes the hind part of the body is curved and prehensile, so that they are able to secure a hold by twisting this part of the body round corals, sea-weed, or any other projecting object. Their tail answers all the purposes of the same organ in fish, and their motions in the water are almost as rapid as they are uncertain and awkward when the animals are removed out of their proper element. Their nostrils are placed quite at the top of the snout, as in crocodiles and in fresh-water snakes, so that they are enabled to breathe whilst the entire body and the greater part of the head are immersed in the water. These openings are small and subcrescentic, and are provided with a valve interiorly, which is opened during respiration, and closed when the animal dives. They have very capacious lungs, extending backwards to the anus, and consequently all their ribs are employed in performing the respiratory function; by retaining air in these extensive lungs they are able to float on the surface of the water without the slightest effort, and to remain under water for a considerable length of time. The scales of sea snakes are frequently very different from those of other snakes: they overlap one another in only a few species; in others they are but imbricate and are rounded behind; and in others they are of a subquadrangular or hexagonal form, placed side by side, like little shields. The less imbricate they are the more they have lost the polished surface which we find in other snakes, and are soft, tubercular, sometimes porous. Sea snakes shed their skin very frequently; but it peels off in pieces as in lizards, and not as in the freshwater snakes, in which the integuments come off entire. Several species are remarkable for the extremely slender and prolonged anterior part of the body, which is termed the "neck," and terminates in a very small head. The eye is small, with round pupil, which is so much contracted by the light when the snake is taken out of the water that the animal becomes blinded and is unable to hit any object it attempts to strike. The tongue is short, and the sheath in which it lies concealed opens near to the front margin of the lower jaw; scarcely more than the two terminating points are exserted from the mouth when the animal is in the water. The mouth shuts in a somewhat different way from that of other snakes: the middle of the rostral shield is produced downwards into a small lobule, which prevents the water from entering the mouth ; there is generally a small notch on each side of the lobule for the passage of the two points of the tongue. Cantor says that when the snake is out of the water and blinded by the light it freely make use of its tongue as a feeler. The food of sea snakes consists entirely of small fish; the present writer has found all kinds of fish in their stomach, among them speices with very strong spines (Apogon, Siluroids). As all these animals are killed by the poison of the snake before they are swallowed, and as their muscles are perfectly relaxed, their armature is harmless to the snake, which commences to swallow its prey from the head, and depreeses the spines as deglutition proceeds. There cannot be the slightest doubt that sea snakes belong to the most poisonous species of the whole order. Russell and Cantor have ascertained it by direct observation: tortoises, other snakes, and fish died from their bite in less than an hour, and a man succumbed after four hours. Accidents are rarely caused by them, because they are extremely shy and swim away on the least alarm ; but, when surprised in the submarine cavities forming their natural retreats, they will, like any other poisonous terrestrial snake, dart at the disturbing object ; and, when out of the water, they attempt to bite every object near them, even turning round to wound their own bodies (Cantor). They cannot endure captivity, dying in the course of two or three days, even when kept in capacious tanks. The greatest size to which some species attain, according to positive observation, is about 12 feet, and therefore far short of the statements as to the length of the so-called sea serpents (see SEA-SERPENT). The largest examples the present writer has seen measured only 8 feet.
Passing over Rattlesnakes (fig. 16) and Vipers, which are treated of in separate articles, we notice the following types of the fourth sub-order, the Ophidii viperiformes.
Death adder of Australia. The sole representative of the sub-order in Australia is the Death Adder (Acanthophis antarctica), a short stout snake having a similar habitus and habits to vipers and scarcely attaining 3 feet in length. It differs from the other Viperines in having tha poison-fang permanently erect. Although much feared, and justly, there is reason to believe that its bite is not so dangerous as has been represented, and that the majority of the fatal accidents ascribed to it are in fact caused by other snakes, probably Hoplocephalus curtus. It occurs tbroughout the whole of Australia, except Tasmania and perhaps South Australia. Generally it is of a uniform grey colour, relieved by some forty dark rings of irregular outline.
Daboia russellii. The "tic-polonga" of the Singalese (Daboia russellii) is beautifully marked : on a light chocolate ground colour three series of large black white-edged rings run along the back and sides of the body, a yellow line borders the surface of the head on each side, the two lines being convergent on the snout. It attains to a length of 50 inches, and occurs locally in abundance in southern India, where it is called "cobra monil" ; in Bengal, where it is called "jessur"; in the plains of central India, as well as in the Himalayas to an altitude of 6000 feet; and in Burmah. It is highly poisonous, probably causing many deaths. Fortunately its loud hissing when disturbed warns those who come within dangerous proximity to it.
Echis. The small Viperine snake, Echis carinata (fig. 17), which scarcely exceeds a length of 20 inches, shares with the preceding part of its range, being found in the and districts of southern India, and extending through the intervening parts of Asia to North Africa. It is a desert type, having the lateral scales curiously arranged, strongly keeled, with the tips directed downwards. It produces with their aid a rustling sound. Whilst some observers deny that fatal consequences have resulted from its bite, Dr Imlach reports that it (the "kuppur") is "the most deadly poisonous snake in Sind." This desert type is replaced farther south in Africa where vegetation flourishes by a closely allied genus, Atheris, which, however, possesses a prehensile tail and vivid coloration and has assumed truly arboreal habits.
Pit vipers without rattles. Of the pit vipers without rattles the largest and most formidable inhabit tropical America. Trigonocephalus iararaca, T. atrox, and T. lanceolatus attain to a length of 6 feet, the first two being common in Brazil and northwards to Central America. The last is limited to some islands in the West Indies, especially Martinique and St Lucia, and is generally known by the name of "fer de lance," which has been given to it from the markings on its head. It infests the sugar-plantations, and has greatly multiplied in consequence of the protection which the cover of the cane-fields afforded it, and the abundance of food supplied by the rats which swarm on the plantations. Thus, whilst it did a certain amount of good by the destruction of vermin, it caused a great number of deaths among the black labourers who were engaged in the fields. These three species of Trigonocephalus are surpassed in size by Lachesis mutus, probably the largest of terrestrial poisonous snakes, which is said to exceed a length of 10 feet, and is bulky in proportion. It is confined to the hottest parts of tropical America. Similar snakes, but smaller in size, inhabit the warmer and temperate parts of North America, viz., the Copper-head (Cenchris contortrix) and the Crater-mocassin (C. piscivorus), the former of terrestrial habits, the latter being always found near water and feeding chiefly on aquatic animals. Both are much feared and cause accidents more frequently than rattlesnakes, being more aggressive and striking the intruder without previously warning him of their presence. In the Indian region this type of pit vipers without rattles is likewise well represented, one genus (Trimeresurus) being adapted for an arboreal life, like Atheris among the Viperidae. Their body (fig. 18) is not more elongate than that of other ground Crotalines, but their tail is prehensile, and their colour generally resembles that of the bright foliage among which they live. Sometimes bright yellow or red markings render these snakes still more pleasing to the eye. Accidents caused by them are of not uncommon occurrence, but fortunately only a few individuals exceed a length of 2 feet, and the consequences of their bite are less to be dreaded than of that of other allied genera. Indeed, numerous cases are on record which show that the constitutional symptoms caused by their poison were of short duration, lasting only from two to forty-eight hours, and being confined to nausea, vomiting, and fever. The bite of larger specimens, of from 2 to 3 feet long, is more dangerous and has occasionally proved fatal. They feed on frogs, mammals, and birds. (A. C. G.)
191-1 The Thanatophidia of India, fol., London, 1872.
191-2 Reptiles of British India, London, 1864, 4to.
197-1 Good descriptions and figures of all these snakes are given in Kreffts Snakes of Australia, Sydney, 1869, 4to.
The above article was written by: Albert Günther, M.D.