Part 18

Points to be noted in the external appearance of the Common Lizard, when we have succeeded in capturing one, are the fact that the entire body is clothed with smooth, slightly keeled, and scarcely overlapping scales, small on the upper side, excepting the head, where they are large. On the underside, too, they are larger, especially from the breast to the vent, where they become broad plates, of which there are six rows, the two central rows being much smaller than the lateral ones. A row of larger scales forms a sort of collar across the underside of the neck. The Lizards have not that fixed, ever-open-eyed stare of the Snakes. The Lizard can follow your movements with his eye, and wink at you intelligently, because he is provided with eyelids, which the Snake lacks. He closes his eyes in sleep. When he puts out his tongue to ascertain whether an insect is good for food, you will notice that the broad tip of it is notched into two rounded lobes, instead of being forked into two thread-like points, as in the snakes. The usual attitude of the Common Lizard is with the extended tail and greater part of the body resting on the ground, or other support, whilst the head and foreparts are raised on the arms, and the muzzle turned to one side in an attitude that suggests listening. It has been stated that Lizards are susceptible to musical sounds, and that they may be attracted from their hiding-places by judicious whistling.

On the underside of the thighs will be found a row of small, roundish scales, all perforated, and numbering from seven to thirteen. The perforations are filled with a yellowish or brown substance, which appears as a little cone above the opening. Its purpose has not been settled satisfactorily, but Cope suggests that it may be for giving the Lizard a better hold on slippery surfaces, seeing that the weight of the body rests chiefly upon the thighs. Another point that should be mentioned is the brittleness of the tail. In catching--or attempting to catch--a Lizard, he should be grasped by the shoulders. If the tail be held instead, it will probably come away in the hand, snapping at the base as readily as though it were glass or sealing wax. A sort of tail will grow from the stump if the Lizard lives long enough, but it is always a poor, ungraceful affair.

This species is the Furze Evvet of the New Forest, and the Harriman of Shropshire. In Cheshire it is the Swift. In suitable situations--sandhills, fallows, heaths, and moors--it may be found all over Great Britain, including the Isle of Man, and in most localities it is common. It is the one true reptile that Ireland possesses, and it appears to occur in all parts of the island, though not in any abundance. It appears (like the Natterjack) to have escaped the attentions of St. Patrick when "He gave the snakes and toads a twist and banished them for ever." Its wider distribution includes Northern and Central Europe and Siberia, where it shows a preference for mountainous and high-lying country.

*Sand Lizard* (Lacerta agilis, Linn.).

At a glance there is little beyond its superior size to distinguish the Sand Lizard from the Common Lizard; and in consequence the earlier records of its occurrence in certain localities have had to be severely revised. It appears to have been the rule of many recorders, when specimens of the common species that exceeded average proportions were captured, to put them down as Sand Lizards without any critical examination. The truth is that as a British species the Sand Lizard is found only in certain restricted localities in the southern counties of Dorset, Hampshire, and Surrey, and the sandhills by the sea in Lancashire and Cheshire. Its southern habitats agree almost exactly with those of the Smooth Snake, for which it provides a favourite food. It is not found either in Scotland or Ireland.

The adult male of the Sand Lizard is about seven and a half inches long, of which more than half is tail. The female is about half an inch longer, but the additional measure is added to the body, for the tail is less than half of the whole length. The general colouring may be described as a sandy-brown, with broken bands of darker tint. There is, of course, a considerable amount of colour variation, and in the males there is a marked tendency to a green suffusion, which in many cases is so pronounced as to lead to a belief that the examples in question are the non-indigenous Green Lizard (Lacerta viridis). It was, no doubt, some markedly green males of the Sand Lizard which Gilbert White saw "on a sunny sandbank, near Farnham, in Surrey," and thought were true Green Lizards. There are rows of dark and white spots along the sides of the back, flank, and tail, which give the appearance of longitudinal stripes. The green of the male is more pronounced during the breeding season (May-June) when it is also evident in the usual black-dotted yellow of the underside. The black spots along his sides have white centres. The under parts of the female are cream coloured, and the three rows of white-centred spots on the sides are dark brown.

The female deposits from five to twelve--usually about eight--eggs which have white shells of the consistency of parchment. These are covered with sand or leaves, and left for the sun to incubate. They are laid in July, and the young are hatched in the same month or early in August. The young Sand Lizards are grey-brown above and whitish below.

Like the Common Lizard, the Sand Lizard is very apt to lose its tail by voluntary amputation; and short-tailed specimens are sometimes found which are to be explained by supposing that the original tail has been shed and another grown.

Characters that distinguish the Sand Lizard from the common species will also be found in the general covering of scales--which are strongly keeled--and in the ten to eighteen on the thigh that are perforated, which are triangular, larger and flatter than the corresponding scales in the Common Lizard. If we have an opportunity for examining the mouth, too, we shall find that in addition to the teeth on the jaws there is a row of them--vomerine teeth--on the hinder part of the palate. These are not present in the Common Lizard. Both species spend the winter in a dormant state underground.

Outside England, the Sand Lizard is a native of Central and Northern Europe, its range extending to the North of Russia and Siberia; but it is a lizard of the lower lands, whilst the Common Lizard on the Continent is more plentiful in mountain districts.

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There are two species of Lizards that are natives of the Channel Islands, and strangely one and not the other of these is usually included in lists of British animals because the islands are politically British. But the fauna and flora of the Channel Islands belong to those of the nearest mainland--France--and therefore should not be included among British species unless they occur also in England, Wales, Scotland, or Ireland. The two species referred to are the Green Lizard (Lacerta viridis), with tail equal to three-fourths of its entire length, and the Wall Lizard (Lacerta muralis) of variable brown coloration and a tail one and a half times the length of the head and body. The Green Lizard may sometimes be seen in this country as an escape from captivity, being a favourite subject with the keepers of vivaria.

*Slow-worm* (Anguis fragilis, Linn.).

The average person cannot understand why the naturalist should be so "pig-headed" as to regard the Slow-worm, Blind-worm or Deaf-adder as a lizard when it is so obviously a snake, and has no legs such as a properly constructed lizard should have. If the naturalist were given to argument of the tu quoque order he might retort by asking why the average man persists in styling a swift-gliding reptile a Slow-worm, or one with brilliant eyes a Blind-worm? But the probability is that he will quote Longfellow and tell the inquirer that "things are not [always] what they seem"--that under the close and polished, uniform scaly covering there are vestiges of limbs that have been discarded in the long evolutionary history of the species; that it has eyelids like other lizards, that the two sides of the lower jaw have a bony union in front, and that it has a notched not forked tongue--characters that do not agree with the structure of any snake. But all this will fall upon deaf ears, and the average man will go on slaughtering Slow-worms at sight, and believing that he has done a brave and meritorious thing.

The Slow-worm attains a maximum length of seventeen or eighteen inches, but the average "large" example is about a foot long. Its head is quite small and short, not so broad as the body just behind it. The tail, which is much longer than the head and body, and longer in the male than in the female, tapers gradually, and is very slender before ending in the short sharp point at the tip. In many examples this graceful tapering of the tail is not evident, because at some time it has been broken short, and the effort to renew it, whilst it gives a sort of finish, never appears to be a success. There is usually a ragged end to the old part, and the narrower new part appears to have been rather clumsily stuck inside the fringe of old scales. Many specimens are in this condition, for the Slow-worm is much more ready to part with its tail than either of our other lizards. The scales on the upper and under sides are nearly uniform in size and shape, broader than in the other lizards and rounded on the hind margin which is thinner than the dark coloured central part of the scale. The scales are quite without keels, polished and plainly overlap their fellows. There is a thin dark line down the centre of the back, and another on the upper part of each side.

The small mouth has the jaws well armed with uniform slightly curved teeth, whose points are all directed backwards. The bright eyes are placed low down, not much above the upper jaw. The head is covered by much larger scales than usual, but in this case the head regions are not so clearly mapped out as in the other species, owing to the thin edges of the scales giving no strong outlines. With a live Slow-worm in the hand one gets a clear idea of the smoothness and close attachment of the scaly covering. The feeling conveyed is that there are no scales: that the external coat is continuous and homogeneous; and one marvels at the reptile's power of gliding rapidly through the fingers. Though the Slow-worm may be found on the edge of the wood, or on the heath, sunning itself early in the spring, and apparently a lifeless casting in bronze, on the slightest alarm it dives into the vegetable soil and speedily disappears. In its basking attitude Slow-worm may be an appropriate name; but when it begins to move we are astounded that it has been able to keep so ridiculous a name.

The food of the Slow-worm is governed by the small size of the mouth. It is not an easy matter to study its feeding habits when it is at large, and our knowledge of its food preferences have been derived mainly from Slow-worms in captivity. It will take spiders, small earthworms, and small insects; but always shows a marked preference for the small greyish-white slug (Limax agrestis) that is so great a pest to the grower of tender vegetables. This slug the Slow-worm consumes in quantity. Dr. Gerald Leighton, in his book on the "British Lizards," says: "I can vouch for a meal that consisted of seventeen slugs, the Slow-worm being a large male sixteen inches long. But the usual number taken seems to be from four to ten." Its principal feeding time is soon after sunset, when the slugs are most in evidence on the surface and beginning to make their nefarious attacks on the food of man. If the gardener, professional and amateur, could only be taught such facts, the sudden descent of the sharp edge of spade or hoe upon one of his ablest helpers might be stayed. The reptiles and the batrachians are all his friends.

Like the Common Lizard, the female Slow-worm retains her eggs until they are fully developed, so that in August or September she produces a litter of six to twelve animated silver needles about two inches in length, with a thin black line along the centre of the back, and black on the underside. These are very active and very beautiful, perfectly independent and able to fend for themselves, catching insects, but at once showing preference for slugs if these are to be found of a size small enough to pass the tiny mouth. There is a record of a batch that were three inches in length at birth, but this is unusual. Occasionally the eggs are deposited before hatching.

Although in early spring the Slow-worm may be seen along hedgerows frequently in the daytime, later in the year it must be sought in the dusk when it is food-finding. It then spends the day under flat stones and in burrows. In Cornwall years ago we could always find a number of Slow-worms by turning over such loose stones along the top of the cliffs; and we have since found them pretty generally distributed without much regard to the nature of the soil. Its principal enemies--besides man--are the Viper and the Hedgehog. In the winter the Slow-worm retires--often in the company of half a dozen or so of its own kind--into an underground burrow or a hollow beneath a large stone, and goes to sleep; but it is the first of the reptiles to reappear at the very beginning of spring. Like its congeners it casts its skin from time to time--apparently about four times a year, but the frequency of the sloughing depends, of course, upon whether it is a good slug year or the reverse, for the shedding of the cuticle is in response to the demand for more room for the growing body. The Slow-worm's length of life is not known; but it does not appear to attain to sexual maturity until it is four or five years of age. We have reliable knowledge of one that was captured when about a foot in length (probably five or six years old), fifteen years ago, which is still healthy and active.

It was in the Slow-worm that the discovery was made in 1886 of vestiges of a degenerate median eye connected with the pineal gland--a discovery that set all the biological investigators of the world at work. The same gland has in the last few years been found to have important influence in controlling the growth of the body in all vertebrates.

The Slow-worm is generally distributed throughout the British Islands, with the exception of Ireland; it is much more plentiful in the south and south-west of England than in the east or north, but even in the south it is much more abundant in some districts than in others. Its wider range includes all but the extreme north of Europe, Western Asia, and Algeria.

SNAKES

*Grass Snake* (Tropidonotus natrix, Linn.).

Before entering upon a description of the greatly feared though harmless Grass, Ringed, or Common Snake, it would be well to say a few words on the structure of Snakes in general, and so avoid some amount of repetition, for in a general way our three species are alike.

The Slow-worm, our legless Lizard, affords a convenient transition to the Snakes; but the bony skeletons of Snake and Slow-worm exhibit considerable differences. No Snake possesses a breastbone, bladebone, or collarbone, so that all the ribs are free at their ends, and they are strongly curved to produce the cylindrical form of body. When bulky food is taken the ribs can be flattened out to allow of the necessary distension of the body until digestion and muscular pressure have reduced the bulk. The bones of the skull are connected so loosely that the head can be flattened and widened, so that the mouth can admit prey equal to three times the size of the Snake's head under normal conditions. To assist in the swallowing of such large bodies, the two halves of the lower jaw have no bony connection but are united instead by elastic ligaments, so that each half can be moved independently of the other, and by the alternate movement of the two sides with the teeth all pointing backwards the food is worked back to the throat. There are other teeth on the roof of the mouth which make it difficult for living prey to struggle forward and escape when once it has been seized. The teeth are all thinly coated with enamel, and are not planted in sockets. If they should get broken by the severe work imposed upon them, they are soon replaced by others which lie in reserve. Poison fangs are much larger than ordinary teeth, and the enamel is folded so as to produce a groove down which poison is pressed from a gland into the wound made by the point of the fang. The fang is hinged at its base and ordinarily lies pressed back upon the upper jaw, and is only "erected" when the Snake is prepared to strike.

Externally the Snake is covered by small overlapping scales on the upper parts and by broad plates on the under surface. The head is covered mainly by shields, each of which has a definite name, but for the purposes of this book it is not necessary to enter upon a tedious recital of these terms, beyond giving them for reference under the diagram of a Snake's head.

The eyes of a Snake are always wide open, for there are no movable eyelids to close them. The eyeball has slight power of movement under its transparent cover, which protects it much as the watch-glass protects the delicate hands of the watch. As in the Slow-worm, there is no external indication of ears, though these are present under the scales. The very long and slender tongue divides forwards into two branches, and when not in use is drawn into a sheath at its base. It is constantly used to ascertain the nature of things by contact, and for this purpose is protruded through a little gap in the front of the upper jaw. The gape of the mouth extends far beyond the eye. The forward extremity (glottis) of the wind-pipe can be thrust outside the mouth when, owing to the passage of a bulky victim, there is danger of obstruction by compression.

The British Snakes represent the two families Colubridæ and Viperidæ.