Venoms: Venomous Animals and Antivenomous Serum-therapeutics. A. Calmette
Poisonous snakes are especially common in the tropical zones of the Old and New Worlds. The species found in Europe are but of small size and not very formidable. In hot countries, on the other hand, they attain large dimensions, their venom is much more active, and, although they hardly ever attack man, and in most cases avoid him, they cause a considerable number of fatal accidents.
It is sometimes a rather difficult matter to recognise from the mere appearance of a snake whether it is poisonous or not. Naturalists themselves are occasionally deceived. It is therefore useful to learn to distinguish the most dangerous species by their external characters, and to know in what countries there is a risk of their being encountered.
A.—EUROPE.
Of the continents of the Old World, the poorest in poisonous snakes is Europe. The only species found there are a Cœlopeltis (belonging to the Sub-family Dipsadomorphinæ of the Opisthoglypha), and certain Viperinæ, which rarely exceed 75 centimetres in length.
Cœlopeltis, the cranial skeleton and head of which are represented in fig. 20, is characterised by a narrow, concave frontal shield, projecting supraciliaries, short snout, large eyes, with round pupils, two poison-fangs at the back of the upper maxillaries, and a cylindrical body. The scales of the back are finely grooved, and in the adult slightly concave.
Fig. 20.—Maxillary, Mandible, and Head of Cœlopeltis monspessulana.
The coloration, olivaceous-brown, or deep red on the back, becomes on the ventral surface pale yellow with brown streaks, and from five to seven longitudinal series of small spots, which are blackish and edged with yellow on the sides.
The mean total length is 1,800 millimetres. The tail is somewhat tapering, and about 350 millimetres long.
The only European species is Cœlopeltis monspessulana, which is met with pretty commonly in France, in the neighbourhood of Montpellier, and Nice, near Valencia in Spain, and in Dalmatia. It is likewise found throughout North Africa, and in Asia Minor.
A second species, Cœlopeltis moilensis, occurs in Southern Tunis, Egypt, and Arabia.
The European Viperinæ belong exclusively to the Genus Vipera, the principal zoological characters of which are as follows:—
Head distinct from the neck, covered with small scales, with or without frontal and parietal shields; eyes small, with vertically elongate pupils, separated from the labials by scales; nostrils lateral. Body cylindrical. Scales keel-shaped, with an apical pit, in from 19–31 rows; ventral scales rounded. Tail short; subcaudal scales in two rows.
The Genus Vipera is represented in Europe by several species, which are likewise found in Western Asia and North Africa.
These species are:—
V. ursinii, V. berus, V. aspis, V. latastii, and V. ammodytes. 1
Vipera ursinii.
Snout obtuse, soft on its upper surface, with the frontal and parietal shields distinct, the former about one and a half times as long as broad, and almost always longer than the parietals. A single series of scales between the eyes and the free margin of the lips.
Temporal shields smooth. Body scales in from 19 to 21 rows, strongly keeled on the back, less strongly on the sides.
Colour yellowish or pale brown above, grey or dark brown on the sides, sometimes uniform brown; spots more or less regular on the vertebral column, oval, elliptic or rhomboidal, dark brown or flecked with white, sometimes forming an undulous or zigzag band; two or three longitudinal series of dark brown or black spots on the sides; small dark dots running obliquely from the eye to the angle of the mouth; nose and lips white, and one or two dark angular streaks on the head; chin and throat yellowish; belly black, with transverse series of white or grey dots. No sexual differences in coloration.
Total length from 420–500 millimetres; tail 50–55.
Habitat: South-east France (Basses-Alpes); Italy (Abruzzi); Istria; Mountains of Bosnia; Plains of Lower Austria; Hungary (environs of Buda-Pesth).
Vipera berus (Common Viper, or Adder).
Snout rounded, short and truncate; pupil vertically elongate; vertical diameter of the eyes equal to or greater than the distance separating them from the mouth; frontal and parietal shields distinct, the former as long as broad, usually shorter than the space separating it from the rostral shield; 6–13 scales round the eyes; one or rarely two series of scales between the eyes and the lips; nasal shield single, separated from the rostral by a naso-rostral shield; temporal scales smooth. Body scales in 21 rows (exceptionally 19 or 23), strongly keeled; 132–150 ventral shields; 38–36 subcaudals.
Fig. 21.—(1) Vipera berus; (2) Vipera aspis; (3, 4) Vipera ammodytes. (Natural size.)
Colour very variable, grey, yellowish, olive, brown, or red above, generally with an undulating or zigzag band along the vertebral column, and a series of lateral spots. A black spot shaped like a V, an X, or a circumflex accent, on the head. The tip of the tail is yellow or reddish. Some specimens are entirely black.
Total length from 350 to 700 millimetres; tail 75 to 90.
Habitat: Northern Europe, and especially the mountains of Central Europe; irregularly distributed in Southern Europe; Northern Spain and Portugal, Northern Italy, Bosnia, Caucasus.
This viper, which is very common in France, ranges as far as the Scandinavian Peninsula to about the 65th parallel of North Latitude. It is sometimes met with among the mountains at an altitude of about 6,500 feet (2,000 metres). It is found on heaths, in grass-lands, vineyards, and forests. Certain parts of the sandy moors of North Germany are literally infested with it. It abounds in the Jura, Isère, Ardèche, Auvergne, Brittany, Vendée, and the Forest of Fontainebleau.
It seeks its prey by night, and feeds on voles, small birds, frogs, lizards, and small fish. During the summer it shows a preference for moist places, often even remaining in the water, in which it swims with ease.
Light and fire attract it. It does not climb trees, but is frequently found coiled up on boughs of dead wood scattered on the ground.
When on the defensive, and preparing to bite, it throws its head back, and makes a sudden dart of from a foot to sixteen inches. If irritated it makes a sort of hissing noise.
To pass the winter it retires into the crevices of rocks or into old tree-trunks, where it entwines itself closely with a number of its congeners. In this way ten or fifteen vipers are frequently found together in the same hole.
In April, the whole company awakes, and copulation then takes place. The eggs are laid in August and September, and the young immediately crawl out of the shell, already prepared to bite, and capable of finding their own food. Their length at birth amounts to 230 millimetres.
The two glands of an adult adder contain about 10 centigrammes of poison. This small quantity is sometimes sufficient to cause death; out of 610 persons bitten, Rollinger returns 59 deaths, or about 10 per cent.
In the departments of Vendée and Loire-Inférieure alone, Viaud Grand Marais has noted during a period of six years 321 cases of bites from adders, 62 of which were