Natural History, Reptiles/Sauria
ORDER III. SAURIA.
(Lizards.)
The Sauria or true Lizards, resemble the Crocodiles in their external form, the body being lengthened and tapering to the tail, which is likewise long, in the possession of four limbs (at least in most cases), and in the presence of numerous teeth. They have a moderate number of perfect and moveable ribs, capable of being raised for the purpose of respiration. The lung extends more or less towards the hind part of the body, often penetrating into the abdomen. Their skin is covered with scales, which in many overlap at the hinder edges; in others are flat, with the edges in common contact, and in some are so minute as to impart a kind of granulated or shagreened surface. "The eyes are furnished with eyelids; the ear in some protected by a simple valve, in others by scales rather larger than the surrounding ones, and in others the tympanum is on a level with the surface of the skin."
The ordinary mode of reproduction is by eggs, which are coated with a calcareous, brittle shell: those of the Chameleon, however, have the covering tough, resembling parchment. In the extensive Family of the Skinks, all the species, as we believe, are ovoviviparous, as are also some of the Lizards proper, for example, our own little Zootoca. The young come into existence in the same form which they retain through life.
"The passage from the Lizard tribe to the Serpents," observes Mr. Bell, "is by a succession of very gradual modifications of development. In the lower forms of the Saurian group, the body becomes gradually elongated and serpentiform: its ribs increase in number, the anterior and posterior limbs are removed farther and farther from each other, and diminish in size and power, exhibiting in some forms the anterior, and in others the posterior only, external to the integument, until at length they cease to appear, being merely rudimentary, and wholly covered by the skin. Of this transition state we have an example in the common Slow-worm (Anguis fragilis), which, though completely serpentiform in its external, appearance, yet possesses the minute rudiments of limbs entirely concealed under the integuments. Notwithstanding this general form of the Serpent, they have not the expansible jaws of the true Serpents: nor is the character of the ears the same, the tympanic membrane not being superficial, nor the auditory passage covered by integument; the eyes, also, like those of the Lizards, are furnished with moveable eyelids, which are wholly wanting in the true Serpents." . . .
"The movements of the Saurian reptiles are effected principally by means of their feet, and in some of the higher forms exclusively so; but as they descend towards the more elongated form of the Skinks and other genera, in which these organs become more and more subordinate, they are greatly assisted by the lateral motion of their bodies, different parts of which are brought into alternate contact with, and pressure upon either the roughness of the ground or the shrubs and herbage through which they pass. A comparison of the progression of these, however, and even of the Slow-worm, with that of the true Snakes, will show that the latter only employ the free termination of their ribs as organs of locomotion. In these the ribs serve absolutely and perfectly the function of feet, and with the exception of their being covered with integument, their action is exactly that of the multitudinous feet in the Scolopendra or Julus, the whole series of ribs coming into contact in succession. At the same time, it is upon the lateral pressure of successive portions of it, that the Serpents mainly depend for the rapidity of their progression."[1]
The Sauria are, we believe, exclusively land-animals, none of them being fitted for inhabiting the water, though some are able to swim, in emergency. Most of them are terrestrial, but not a few are arboreal, more or less entirely, from the Chameleon, which, with his opposible toes, climbs about the branches of trees, to the little Anoles, which run about the trunks and leap from leaf to leaf; and some, as the Geckos, inhabit the crevices of old buildings, among the rafters of which they crawl in all positions, frequently with the back downward. These last are rather slow in their motions, and the Chameleons are still more deliberate; but the characteristic of the Order is extreme agility, and some of the ground Lizards dart to and fro, and skim the surface of the earth with the rapidity of a bird. In one genus, Draco, the skin of the sides is stretched upon a prolongation of the ribs, and acts as a parachute, or as the membrane of the Flying Squirrels, enabling them to take long leaps from tree to tree.
The food of this Order consists principally of insects, but the Monitors of tropical America, which approach the Crocodiles in size, and in some other peculiarities, are said to prey upon other reptiles, the eggs of birds, &c.; and the Iguanas feed on fruit, as does also the Gallywasp of the West Indies, one of the Scincidæ, as we know from personal observation. Mr. Darwin mentions a species of Amblyrhynchus, a native of the Galapagos Islands, which swims out to sea, in order to feed on the sea-weeds that grow at the bottom.
Several of the foreign species are used as human food; Humboldt asserts that all the South American kinds within the tropics, that inhabit dry regions, are esteemed delicacies for the table. The flesh is white, and is said to resemble that of chicken. The Iguanas of the West Indies have always been prized by the Spanish settlers, though the English have commonly rejected them from prejudice.
The tropical regions of the globe swarm with Lizards, the species of which are very numerous; the grassy turf, the sandy plain, the sunny bank, the trees and bushes, the dilapidated wall, every heap of stones, and even the houses of the inhabitants, have their Lizards; some of which are of pleasing forms, most are distinguished for agile and graceful motions, and many are arrayed either in burnished mail, or in various brilliant hues. The colours of some, as the Chameleons, and the Anoles, are subject to changes, not produced by the play of light, as from the iridescent scales of some Serpents, but by actual alteration of tint, at the will of the animal. Most of them throw off the cuticle, at periodical intervals, which retains the form of every scale and plate, impressed convexly on the outer surface, and concavely on the inner. After the sloughing, the new surface is more brilliant than the old. The swift and bright-eyed little Lizards darting and leaping everywhere, in tropical countries, form an attractive feature of the scene, and are not regarded with the fear and disgust with which reptiles are foolishly regarded too often with us. Moore alludes to the beauty of these little creatures,—
"Gay Lizards glittering on the walls
Of ruin'd shrines, busy and bright,
As they were all alive with light."
The Families of the Sauria have been greatly multiplied by some zoologists: we shall prefer to consider them as seven in number; Chamæleonidæ, Geckotidæ, Iguanadæ, Agamadæ, Varanidæ, Lacertadæ, and Scincidæ.
Family I. Chamæleonidæ.
(Chameleons.)
This small but compact and well-defined Family is not only the most anomalous among Reptiles, but perhaps even amongst the whole range of Vertebrate animals. They are distinguished at once by the character of their feet, which is strictly Scansorial, and recalls the form which those organs assume in the Monkeys among Mammalia, and in the Parrots and Woodpeckers among Birds. The toes are five, as in the majority of Saurians, but these are arranged in two sets, three in one set, and two in the other, each set being enveloped in the common skin as far as the claws. These two parcels of toes are opposible to each other, and thus each foot forms a true grasping hand, and is used in the manner which this structure indicates; the Chameleon moving with slow and deliberate steps, always grasping with a firm hold the branch on which it is creeping, before the other feet are relaxed for a fresh step. The tail is round and prehensile at the tip, like that of the American Monkeys; its under surface is roughened, with small granulated papillæ as is that of
the toes also, probably for the more delicate perception of the surface grasped. The tongue affords an analogy to the same organ in the Woodpeckers, no less singular than that of the feet; for though ordinarily concealed within the mouth, it is capable of being darted forward at its insect prey, and being furnished with a glutinous secretion, secures it by its adhesiveness.
One of the most remarkable features in the physiognomy of the Chameleons is the peculiarity of their eyes; these are large, full, and prominent, entirely covered with the common shagreened integument, except a small round aperture opposite to the pupil. Unlike all other vertebrate animals, their eyes act independently of each other, so that one may be directed to an object before, while the other remains still, or is looking behind.[2]
The head in the Chameleons is large, somewhat triangular in outline, and appears set upon the shoulders without the intervention of a neck; it is very broad across the occiput, where it is surmounted by an elevated process, greatly developed in some of the species; ridges also proceed over the eyes, which meet at the muzzle, and are sometimes much prolonged.
The Chameleons, though constituting but a single genus, comprise numerous species, which are scattered over the warmer regions of the eastern hemisphere, from the south of Spain, and the countries bordering the Mediterranean, to Australia. No species is known to exist in America, where the genus seems to be replaced by Anolis and its allies.
Genus Chamæleon. (Cuv.)
As the peculiarities of this genus have already been traced at some length in our account of the Family which it alone constitutes, we need not recapitulate them, but shall confine ourselves to some particulars of the history of the best known species, and an examination of some interesting phenomena, which are displayed by the whole tribe.
CHAMELEON.
The Common Chameleon (Chamæleon vulgaris, Cuv.) is about ten inches in length; the occiput is arched and compressed. It is distinguished from a species found in Central Africa by the occipital keel reaching forward to the centre of the eye, by the back of the head being only slightly lobed, and by the frontal scales being tubercular. It is spread over the whole north of Africa, and the south of Asia, and is said to extend even into Spain.
The changes of colour to which this reptile is subject are so curious as to have attracted popular observation from early times; and though much of fable has been mingled with the descriptions of the phenomenon, it is still exceedingly interesting; and not the less so because of the obscurity which has huug over the causes of the changes, baffling the researches of acute physiologists, and giving rise to many diverse theories. The popular notion is that the Chameleon assumes the tint of the surface on which it rests, becoming green on a leaf, brown on the branch of a tree, white on a stone, &c., but this opinion is at variance with fact, and is now universally exploded by naturalists. Hasselquist, who considers the changes to be the result of a kind of disease, remarks, that he never observed the Chameleon assume the colour of an external object presented to its view, although he made several experiments for the purpose. He says that its natural colour is an iron grey, or black mixed with a little grey. This it sometimes changes, and it becomes entirely of a brimstone yellow, which, except the former, is the colour it most frequently assumes. It sometimes takes a darker or greenish yellow, and sometimes a lighter. He did not observe it assume any other colours, such as blue, red, purple, &c. When changing from black to yellow, the soles of its feet, its head, and the bag under its throat, were the first tinged; and then by degrees that colour spread over the rest of the body. He several times saw it marked with large spots of both colours all over its body, which gave it an elegant appearance. When it became of an iron-grey it dilated its skin, and became plump and handsome; but as soon as it turned yellow, it contracted itself, and appeared empty, lean, and ugly; and the nearer it approached in colour to white, the more empty and ugly it appeared; but its shape was always the most unpleasant when it was speckled. Mr. Hasselquist kept a Chameleon for nearly a month. During the whole time it was very lively, climbing up and down its cage, fond of being near the light; and constantly rolling about its large eyes. It took no food during the whole of this time, so that it became lean, and evidently suffered from hunger. At length, through weakness, it fell from its cage upon the floor, when a turtle that was in the same room, bit it, and hastened its death.
M. d'Obsonville's account differs somewhat from the above, and he considers that he has discovered the secret cause of the changes in the blood. "The colour of the Chameleon," he observes, "is naturally green; but it is susceptible of many shades, and particularly of three very distinct ones; Saxon green, deep green, and a shade bordering on blue and yellow green. When free, in health, and at ease, it is of a beautiful green; some parts excepted, where the skin being thicker and more rough, produces gradations of brown, red, or light grey. When the animal is provoked in open air, and well fed, it becomes a blue green, but when feeble, or deprived of free air, the prevailing tint is yellow green. Under other circumstances, and especially at the approach of one of its own species, no matter of which sex, or when surrounded and teased by a number of insects thrown upon him, he then almost in a moment takes alternately the three different tints of green. If he be dying, particularly of hunger, the yellow is at first predominant; but in the first stage of putrefaction this changes to the colour of dead leaves.
“The causes of these changes are various; and first, the blood of the Chameleon is of a violet blue, which colour it will preserve for some minutes on linen or paper, especially on such as have been steeped in alum-water. In the second place, the different tunicles of the vessels are yellow, as well in their trunks as in their ramifications. The epidermis, or exterior skin, when separated, is transparent, without any colour; and the second skin is yellow, as are all the little vessels that touch it. Hence it is probable that the change of colour depends upon the mixtures of blue and yellow, from which result different shades of green. Thus, when the animal, healthy and well-fed, is provoked, its blood is carried in greater abundance from the heart towards the extremities; and swelling the vessels that are spread over the skin, its blue colour subsides, and with the yellow of the vessels, produces a blue green, that is seen through the epidermis. When, on the contrary, the animal is impoverished, and deprived of free air, the exterior vessels being more empty, their colour prevails, and the animal becomes of a yellow green, till it recovers its liberty, is well nourished, and without pain, when it regains its former colour; this being the consequence of an equilibrium in the liquids, and of a due proportion of them in the vessels.”
To mention the various hypotheses by which these interesting changes of colour have been attempted to be explained, would not suit our pages; we content ourselves with adding the conclusions of Dr. Milne Edwards, who, in an elaborate memoir on the subject, is considered by some to have solved the problem. We have room only for the results at which he arrives, which he embodies in the following propositions:
1. That the change in the colour of Chameleons does not depend essentially either on the more or less considerable swelling of their bodies, or the changes which might hence result to the condition of their blood or circulation; nor does it depend on the greater or less distance which may exist between the several cutaneous tubercles, although it is not to be denied that these circumstances probably exercise some influence upon the phenomenon.
2. That there exists in the skins of these animals two layers of membraneous pigment, placed the one above the other, but disposed in such a way as to appear simultaneously under the cuticle, and sometimes in such a manner that the one may hide the other.
3. That everything remarkable in the changes of colour that manifest themselves in the Chameleon, may be explained by the appearance of the pigment of the deeper layer to an extent more or less considerable, in the midst of the pigment of the superficial layer, or from its disappearance beneath this layer.
4. That these displacements of the deeper pigment do in reality occur; and it is a probable consequence that the Chameleon's colour changes during life, and may continue to change even after death.
5. That there exists a close analogy between the mechanism by the help of which the changes of colour appear to take place in these reptiles, and that which determines the successive appearance and disappearance of coloured spots in the mantles of several of the Cephalopods.[3]
Whether this learned zoologist has set the question completely at rest in these observations or not, we may be permitted to doubt; and to inquire with Mr. Martin, “how the mechanical admixture of two pigments can produce the various tints, exhibited at various times by the skin of the Chameleon, as primary yellow, and red, yellowish-grey, brown, and violet, or dull inky blue?”
The Chameleon is vulgarly reputed to feed on air; which absurd notion may have arisen from its habit of frequently inflating its body to an extraordinary degree, when it appears plump and well-fed. The air penetrates even into the feet and tail, increasing the bulk of the animal to double its former size. At other times it becomes quite flaccid, and then has a dreadful appearance of leanness, like that of a skeleton enclosed in a loose skin. In this state the lungs are very small, but when fully inflated, their vesicles cover almost the whole of the viscera. It feeds, like most other Lizards, on insects, to capture which it has no powers of pursuit, for its motions are slow in the extreme. To this slowness there is indeed one exception, without which the creature would starve. Its habit is to lie in ambush, as it were, among the leaves, and watch for flies and other insects that may by chance alight or crawl within reach of its tongue. This organ, as we have said, is capable of being projected to a great length with great rapidity and precision; its tip, which is dilated, is somewhat tubular, and secretes a glutinous fluid, to which, when suddenly launched, the prey adheres, and is in an instant retracted into the mouth.
Some interesting details of the action of this organ, as observed in a state of captivity, are given in a paper by Mr. Houlston, published in the “Transactions of the Irish Society:” “When a fly, so maimed as not to be able to escape, but still sufficiently vigorous to move its legs and wings, was so placed that its fluttering might attract the Chameleon's attention, the animal advanced slowly until within tongue's reach of it; then, steadying itself like a pointer, sometimes stretching out its tail, sometimes fixing it against an adjacent body, and directing both eyes steadfastly on the prey, it slowly opened its mouth and suddenly darted forth its tongue, which advancing in a straight line, seldom failed of striking, with its glutinous cupped extremity, the object aimed at. Near the point of the tongue there is a small gland, which secretes a glutinous fluid, but even when the point happened to err, the prey did not always escape, sometimes adhering to the sides of the tongue. The tongue thus laden, then retired into the mouth, but somewhat more tardily than in its advance. When projected, the tongue acquired a thickness equal to the largest swan-quill, and a length not less, sometimes, than six or seven inches. Its consistence I attempted on one occasion to ascertain, by catching it between my fingers, when it imparted the feel of an elastic body, yielding slightly when pressed on, and expanding as soon as the pressure was removed. The experiment only caused a short delay in its progress, but neither altered its form or course, nor unfastened the prey from its extremity.
“The tongue is probably the sole agent of the Chameleon in obtaining food. Flies have often rested on its body, and though it has looked wistfully at them, it has had no means of taking them. I have frequently observed them on its very lips, without any attempt being made to seize them. Even when placed before it, if not sufficiently distant to afford room for the necessary evolution of the tongue, the Chameleon was under the necessity of retiring for the purpose.
“If the fly happened to be on a flat surface, so placed as to oblige the creature to direct its tongue perpendicularly against the surface, the cupped extremity would adhere, for a short time, in the same manner as a child's leather-sucker does to a stone. But the animal seemed most annoyed when seizing its prey on the sides of its cage, which was made of paper, the down of the paper sticking to the mucus on the tongue. On one occasion when two Chameleons attempted at the same moment to catch a fly placed between them, their tongues struck against each other, and remained connected for a short time.”
In Loudon's "Magazine of Natural History" are recorded some particulars of two Chameleons, which were sent from Malaga, in Spain, and which lived in the possession of Mr. Slight several months. They were kept unconfined in a wicker-basket in a bow-window, and slept many hours in the day, lying on a projecting ridge of the wicker-work. During sunshine, they flattened themselves, to expose a larger surface to its influence, when they were usually of a greenish stone-colour, and pale. If disturbed, they contracted their abdomen, expanding the ribs, and often became instantly of a dark green, or even indigo green. Sometimes only one side changed colour. The larger was vigorous, and in health; when awake, its eye (of a dark colour and very lustrous) was turned in every direction, the motions being by a kind of jerk, and very rapid, as if in search of prey. Mr. Slight was accustomed to put six or seven cockroaches in a shallow tin vessel, and the Chameleon on its edge, with its head projecting over the brim. After making a circuit round a portion of the vessel it would distend the throat-pouch, and stretching forward its body on the fore-legs, it would suddenly dart out its tongue with such force as to make a very sensible ring on the opposite side of the tin. It would catch the insect in the trumpet-shaped extremity of the tongue, which was retracted quick as lightning, and mastication and swallowing followed. In this manner it would take three or four insects from the vessel, but fed only once in three or four days, and would not eat hard-shelled beetles. They generally slept on the top of the basket, their heads projecting over the edge, and their tails curled round one of the small divisions of the wicker-work, and it was curious to observe the firmness of their hold in this way. On going in with a candle, they always appeared of a pale ashy stone-colour or a spectral blue, like the tint cast upon the face by coming opposite a blue bottle in a chemist's window. Their motions were exceedingly slow, always firmly attaching one foot before letting go with the other. They were lost several times, and Mr. Slight was afraid to step about the room, lest he should tread on them, but they were generally found in the folds of the curtain, not on the blue lining, but on the chintz. One side was often seen nearly of a stone colour, while the other was blackish green; the changes of hue were always rapid, and attended by either elevation or depression of the ribs.
Family II. Geckotidæ.
(Geckos.)
The Geckos form a numerous but well-defined Family, widely diffused over the hot regions of both hemispheres. They are all of small size, but of somewhat uncouth proportions, and of repulsive appearance; the head being large and flat, the neck short, the body stout and protuberant, with the line of the back rather depressed than ridged. The eyes are full and large, and being destitute of visible eyelids, always appear staring; the pupil is, for the most part, a perpendicular line by day, with notched edges. The feet are nearly equal, short, stout, and terminated by five toes, differing little in length, which radiate as if from a centre, so as to form two-thirds of a circle. The under surface of the toes is, in most of the genera, much widened, and furnished with small plates, or laminæ, overlapping each other in a regular manner, which varies in different genera and species. The toes are frequently united by a membrane at their base.
FEET OF GECKOS.
The claws are pointed, hooked, and kept constantly sharp, by an apparatus by which they are capable of retraction, like those of the cat. In some genera, however, the claws are wanting.
The jaws of the Geckos are armed all round with a single row of minute teeth, which are compressed, with cutting edges, implanted in the interior surface of the jaw-bone; the palate is destitute of teeth. The mouth is wide; the tongue is thick and fleshy; slightly extensile, with the extremity sometimes notched. The ears are situated on the sides of the head, the tympanum or drum, a membrane sunk considerably below the general surface, the orifice bordered by two folds of skin. The skin is very loosely attached to the muscles, weak, and easily torn: it is roughened with minute granular scales, which, on the sides and hinder parts become more inclined, and overlapping, and on the under parts take the form of regular scales. The tail varies in length, but never exceeds that of the body; like that of most Lizards, it is very brittle, and liable to be separated by accident; it is, however, soon replaced. In some species, the sides of the body, the tail, and the limbs, are furnished with expansions of the skin, sometimes fringed or vandyked in a singular manner. The males have femoral pores more frequently than the females, but not invariably.
"The skull of the Geckotidæ is marked by some peculiar characters. The bones are well-defined,
SKULL OF GECKO.
nor do the sutures seem to be obliterated by age. In general contour it approaches the skull of the Crocodilidæ by its width, its flatness, and its length; its particular resemblances to the same part in that Family are to be found in the disposition of the orbits, and the articulation of the jaws. The excavations for the eyes are very large, and apparently incomplete, inasmuch as the orbital frame is not entirely bony in its back part, nor has it, so to speak, any flooring; so that when deprived of the softer parts, the cavity communicates with the mouth. The articulation of the jaw is quite backward."[4] The spinal column is destitute of any bony processes or projections; the vertebræ are said to be hollowed out, on their anterior and posterior surfaces, into conical cavities, somewhat like the vertebræ of fishes. The number of ribs varies according to the species.
We have said that the skin is easily detached; when held up to the light, it is seen to be regularly furnished with small, delicate, rounded, escutcheon-like bodies, set in its substance. The form and distribution of these bodies are different in different species, and they are found in the skin of the belly, the neck, the head, the thighs, and the tail.
The colours of the Geckos are commonly sombre, and even lurid; frequently various shades of grey and brown, more or less irregularly clouded or mottled; they have the power in some degree of changing their hues, the colours being darker or paler, and the markings becoming visible or evanescent, at will. Some of the small species are marked with bright colours, which are not mutable. Wagler was informed by some travellers, that certain Geckotidæ of India become luminous or phosphorescent during the night; but we know not how far this information is to be depended on. The skin is moulted or sloughed off, at certain times, when that which envelops the head and fore parts of the body is detached first, the separation proceeding gradually to the tail. During the process, which lasts for a day or two, the half-detached skin hangs about the animal in loose folds, resembling the finest muslin, apparently to its great annoyance. The colours of the body after this shedding of the cuticle are much brighter and more definite.
By means of the singular lamellated structure on the under surface of the toes, the Geckos, or at least many of them, are enabled to cling to vertical or even inverted surfaces, as house-flies do. The mode in which this is effected, we do not thoroughly understand; but we may conjecture that it is by the raising of these imbricated plates by muscular action, so as to form a vacuum beneath the sole, when the pressure of the external air causes the toe to adhere firmly to the surface. The similarity of the structure to that of the coronal sucker in the Remora, suggests this explanation. A familiar illustration of the principle is seen in the leathern suckers which children make, which adhere so firmly that large stones are lifted by them.
M. Duméril has noticed a peculiarity in the œsophagus or gullet of this Family, which is the more extraordinary, since the part is not exposed to the light. In many species, both living and dead, which he examined, he found the interior of this tube, which is very wide, strongly coloured with different shades, uniform in the same individual, sometimes orange-yellow, but more generally deep black. We have observed something analogous to this in the rich Vermillion hue of the whole interior of the mouth and vomer of some West Indian fishes.
The names Gecko, Geitje, Tockaie, &c., by which these reptiles have been called in different localities, are derived from the sounds emitted by them, which are supposed to resemble these words. M. Duméril is unable to account for the production of this voice, the more especially as they are destitute of the dewlap, or goître, which we find in the Iguanadæ. He suggests, however, that the movement of the tongue may bear a part in its emission, and the reception of that organ in the concavity of the palate; perhaps in a similar way to that in which the cracking sound is produced by a rider, when he stimulates his horse,—the tongue being applied to the palate, and quickly withdrawn. The goître of the Anoles does not appear to us to be in any way connected with the emission of sounds.
The motions of the Geckos are slow and stealthy: they creep along with an almost imperceptible step, with the chin and belly resting on the surface on which they move; yet on alarm they display surprising agility. They watch, the whole day long, at the mouth of some hole or crevice, the head peeping out; and if they do venture to travel, rarely wander far from their retreat, into which they vanish in an instant, if disturbed. Their senses seem acute, and to be exercised by day, though night is the season of their activity.
The following summary of the habits of these animals we extract from the elaborate article on this Family in the Penny Cyclopædia, though a few of the remarks we have already anticipated, and though we cannot fully agree with some of the conclusions:—
"The Geckotidæ are none of them large in size, and the greatest number feed on small animals, such as insects, their larvæ and pupæ. These they catch either by lying in ambush, or by pursuing their feeble prey in the holes and dark crevices to which it retires. The structure of their feet enables them to run in every direction over the smoothest surfaces, and they can even remain suspended beneath the large leaves which a luxuriant tropical vegetation so frequently puts forth. The sharp or retractile nails with which the feet of the greater number are armed enable them to cling to and make rapid progress on trees with the smoothest bark, or penetrate the holes of rocks, and to climb walls. Of sombre or varying colours, adapted generally to the locality where their lot is cast, they will often remain for hours in positions as extraordinary as the flies and insects for which they watch; the wonderful apparatus with which their feet are furnished enabling them to overcome the general law of gravity, and without which they would instantly fall to the earth. The hues of their skins thus render them less objects of suspicion to the little animals for which they lie in wait, and also serve to dodge even the acute eye of the bird of prey that seeks to destroy them. Their eyes enable them to discern objects in the dark, and are at the same time capable of bearing the rays of a bright sun; for many insects are nocturnal or crepuscular, while the great mass of them are diurnal. The pursuit of their prey leads them near the habitations of man, whose dwelling always attracts certain kinds of insects, and they sometimes fall victims to their appearance, which frequently inspires terror, and often disgust. A Gecko, confident in his powers of flight, appears boldly to await his adversary, and his sudden disappearance at a nearer approach adds to the horror which his uncouth form inspires. The poor Geckos, too, have a bad name. They are supposed to poison whatever they touch, be it animate or inanimate, and their saliva is said to vex the skin of those on whom it falls with foul eruptions. Many of these cuticular irritations, when they have actually existed from the intervention of these animals, may have arisen from the extremely sharp claws of a Gecko running over a sleeping man, or small blisters may have been raised by the adherent apparatus at the bottom of its feet.”
The explanation here given of the baneful effects supposed to be produced by the feet of some species of this Family, though repeated in most works on the subject, seems to us futile and unsatisfactory. We do not believe that the adhesion of the suckers of the toes of these minute animals would produce the smallest appreciable result on the skin of a man, in the way of raising blisters, nor that the muscular power with which the little claws are moved would be sufficient to pierce the flesh.
The genera and species which compose the Family are rather numerous, and are scattered over all the great divisions of the globe. Europe, however, has but two, neither of which is found in the British Isles. To Asia, Africa, America, and Australasia, the remainder are distributed in about equal proportions, each of these regions having twelve or fourteen species; the whole amounting to between fifty and sixty.
Genus Thecadactylus (Cuv.).
The claw in this genus is completely retractile; the toes, which are widened throughout their length, being furnished with transverse plates beneath, which are divided by a deep longitudinal groove, to receive the claw. Those known have the innermost toe destitute of a claw, they have no femoral pores, and the tail is clothed with minute scales on both the upper and under surfaces.
The Smooth Sheath-claw (Thecadactylus lævis, Cuv.) has the transverse scales beneath the toes numerous: it is about nine inches in length, of a stout form, of a pale reddish hue, marked with transverse bands of brown; the sides are spotted with red, and there is over each shoulder a black patch with a white dot in the centre. The tail is vertically compressed towards the tip; but this organ is readily detached, not only by violence, but by the convulsive action of the reptile itself, if put alive into spirits. In this latter case the separated tail sometimes contracts and assumes an almost globular form. From having been seen in collections in this state, it has been supposed to be a distinct species, and has been named the Turnip-tailed Gecko (Gecko rapicauda). If the animal escape after having thrown off its tail, a new one will be reproduced in a short time, soon assuming the size and appearance of the old one, and leaving scarcely any trace of the misfortune, as we have proved in specimens in our own possession in captivity.
The Smooth Sheath-claw is a native of Jamaica, where it is very common. From its singular voice, uttered on the approach of night, and continued at intervals through the darkness, it is there called the Croaking Lizard. The sound which it emits might rather be called cackling than croaking, having some resemblance to the
SMOOTH SHEATH-CLAW.
noise produced by drawing a stick across the teeth of a comb. It frequents hollow trees, and the roofs and rafters of deserted houses, a pair generally living together; one or both may commonly be seen, day after day, at the same spot, frequently peeping out of a crevice, and remaining perfectly still for hours. They move with excessive deliberation, but are easily alarmed, when they dart into their hole with inconceivable rapidity. They may often be observed crawling on the vertical side of a beam, but we have never seen one actually inverted.
The food of this species principally consists of insects; but we have frequently found in its stomach substances of a vegetable nature also, as pulpy berries, and seeds of various kinds. Its eggs, which are about half-an-inch in length, irregularly oval and flattened, are laid in any crevice; they are covered with a hard and brittle calcareous shell. The young, when excluded, are exactly like the adult, but have the hues much more brilliant: they are able to run with agility the moment they leave the shell.
The sombre and lurid appearance of this Lizard, its stealthy motions, its nocturnal activity, and singular harsh cry, and especially a certain sinister aspect, produced by its large globular eye, unprotected by an eyelid, and divided by its linear pupil, have doubtless combined to give to it in the popular mind a character for evil, which its fellows in other regions possess, but to which it seems to have no rightful claim; for though dreaded, and vulgarly reputed poisonous, we have every reason to believe that it is a perfectly innocuous reptile.
Family III. Iguanadæ.
(Iguanas.)
Some of the largest and some of the smallest of the Lizards are found in this Family, for while the true Iguanas sometimes measure six feet in length, there are some of the Anoles which scarcely attain half as many inches. It comprises many genera and species, which, with scarcely an exception, are confined to the warmer parts of the American continent and the adjacent islands. They are marked by a long and slender body, and greatly lengthened tail; by having five toes on each foot, which are very unequal in length, those of the hind feet particularly so; by the eye being protected by eyelids, meeting in a longitudinal line; by the tympanum or drum of the ear being membranous, and but little beneath the surface; by the tongue being thick, fleshy, and not extensile, and notched only at the tip; by teeth in the palate; and by numerous others
TEETH OF IGUANA.
attached to the inner edge of the jawbone, which for the most part are lobed or dilated, and have a crenated or notched edge. Besides these distinctions, the body is covered with scales or tubercles, often ridged or spinous, always horny in texture, not bony: those of the head frequently take the form of many-sided plates, more or less large, and those of the belly are square and overlapping. The scales of the back are generally elevated into spinous processes, forming a saw-like crest, which runs down the back and tail in various degrees. The toes are always free, commonly slender; but in some genera, as Anolis, Dactyloa, &c., they have the dilated and lamellated tips of the Geckotidæ. These have the power of crawling with ease and rapidity on perpendicular surfaces, and haunt out-buildings, and even dwelling-houses in the hot parts of America and the West Indies, running with great agility about the walls, and leaping from place to place; while others run and leap with equal sprightliness among the twigs and leaves of low shrubs in pursuit of insects. These have the faculty of changing their colours, which is effected with a rapidity and to an extent scarcely inferior to what we see in the Chameleons. All the genera appear to be more or less arboreal; the larger species, or true Iguanas, living almost entirely on trees: these are reported to be able to swim with ease, but their feet do not manifest any structural adaptation to aquatic habits, and we doubt whether they ever take to the water except in an emergency, or impelled by some unusual motive.
Most of the species in this Family have some expansion of loose skin about the neck. In the Iguanas it hangs down in a permanent sort of dewlap, but in the Anoles it is ordinarily contracted and consequently invisible, but is expanded broadly during excitement. It does not, however, form a bag, nor is it susceptible of inflation, as commonly represented, but is simply extended by means of the branches of the tongue-bone (os hyoïdes), which in repose pass down longitudinally beneath the skin. Under the influence of excitement, the tips of this bony fork are drawn downward and forward, stretching the skin with them, in an elliptical form, the two inner surfaces of the skin being in contact.[5] This goître is almost always of bright colours, usually some tint of orange or red, and is not susceptible of change in hue, as has been erroneously stated even when the colours of the body are mutable.
HEAD OF ANOLIS.
The food of the smaller species of the Iguanadæ consists chiefly of insects, in the capture of which they display great agility. We have, however, seen specimens of the genus Dactyloa (allied to Anolis) engaged in feeding on pulpy berries; and MM. Duméril and Bibron state that in their dissections of many of the larger species they have found the stomach filled with vegetable matters, such as flowers, leaves, and seeds, in considerable quantities, and hence these herpetologists conclude that most of the species are herbivorous. The true Iguanas are said, however, to feed voraciously on animal matters also, such as the eggs of birds, the intestines of fowls, and insects.
An interesting anecdote recorded by Professor Bell of one of the smallest of the Iguanadæ shows that insectivorous animals may be exposed to danger from the noxious qualities of the insects which they attack. “Some years since,” observes this zoologist, “I had in my possession two living specimens of the beautiful little green Anolis of the West Indies, a lizard about the size of our own smallest species. I was in the habit of feeding them with flies and other insects, and having one day placed in the cage with them a very large garden spider, Epeira diadema, one of the lizards darted at it, but seized it only by the leg. The spider instantly ran round and round the creature's mouth, weaving a very thick web round both jaws, and then gave it a severe bite in the lip, just as this species of spider usually does with any large insect which it has taken. The lizard was greatly distressed, and I removed the spider, and rubbed off the web, the confinement of which appeared to give it great annoyance; but in a few days it died, though previously in as perfect, health as its companion, which lived for a long time afterwards.”[6]
Genus Iguana (Laur.).
To this genus, which is very restricted in extent, belong the largest species of the Family, and almost of the Order. They are marked by a prolongation of the skin, which stretching under the whole surface of the head and neck, forms a very thin, but very deep dewlap or pouch, the border of which describes a curve, and is set along its front edge with spinous processes like the teeth of a saw. The skin is irregularly folded on the sides of this dewlap, behind which there is another transverse fold passing obliquely over each shoulder. On the sides of the neck and body, also, the skin has a tendency to form loose folds. The head is rather large, and has somewhat of the form of a four-sided pyramid. The neck is compressed, the body rounded, but flattened on the under surface. The toes are long, and very unequal, increasing rapidly in length from the innermost to the fourth, which is longest, the fifth being short: their edges are notched. The tail is long, slender, compressed, and tapered to a fine point.
The general surface of the body is covered with small square or lozenge-form scales, keeled along the middle, which slightly overlap each other; those of the tail present at regular intervals verticillations or rings, produced by every fourth or fifth series being a little larger than the others, but this structure ceases to be perceptible towards the tip. The line of scales which runs down the middle of the back and tail, forms a saw-like crest, commencing from the hind-head, and reaching the extremity of the tail. It is composed of strongly compressed scales, which are pointed and curved backwards, and which gradually diminish in height towards the end of the tail. On the top and sides of the head the scales are larger than the rest, but varying in size, many-sided, some flat, some convex, and some ridged: the lips are covered with large four-sided plates. The under surface of the thighs has a single row of pores, surrounded by small scales disposed like the petals of a flower around its disk.[7]
We have already mentioned MM. Duméril and Bibron’s conclusions of the nature of these Reptiles’ food from anatomical investigation. These are confirmed by a fact related of a living Iguana, which was kept in a hot-house near Bristol. It had refused to eat insects and other kinds of animal food, until happening to be near some kidney-bean plants, it began to eat their leaves, and was thenceforward supplied with these plants. Other accounts, as we shall presently see, describe them in their native regions as feeding on fruits.
Some writers have enumerated many species of this genus, but the eminent herpetologists above mentioned reduce the whole to three, all of which are widely spread over South America and the
Antilles. The most common is Iguana tuberculata (Laurenti), which, in five stages of its life, has been described and figured by Spix, in his magnificent work on the Zoology of Brazil, under five different names.
This is the common Iguana or Guana of the European colonies, a name which seems to be of Indian origin, and which was probably that by which the reptile was distinguished at the time of the discovery of America. It is said to have been common in the West Indian Isles in former years, but it seems to have disappeared, at least from Jamaica; it is possible, however, that some large species of Cyclura, an allied genus, inhabiting that island, and provincially called by the name of Guana, may have been mistaken for it.
The Green Iguana attains a length of five or six feet; its general hue is green, more or less deep, sometimes merging into blue: the sides are marked with oblique stripes of brown, edged with yellow; a line of yellow frequently appears over the shoulder; the tail is crossed by broad bands of brown, alternating with the green. In some specimens, the sides and limbs are variously clouded or spotted with brown.
The esteem in which the flesh of this reptile is held in the countries which it inhabits is spoken of by most writers who mention its existence. Delicatissima and sapidissima are among the numerous specific names which have been assigned to it. Excellent, however, as is its flavour, it is not considered very wholesome, and to persons labouring under certain diseases it is highly injurious.
In Paramaribo, where the Iguana is considered one of the most delicious animals brought to the daily market, it is always in request and sells at a high price, being immoderately esteemed by those epicures who consider a fricaseed frog preferable to a chicken. The eggs, which are spoken of as very agreeable in flavour, and which are constantly sought after in Surinam and Guiana, have common qualities with those of the Turtle, especially those taken from the gravid Turtle killed for the market;—a yolk that never boils hard, and a slight envelope of albumen that never whitens. They are described as being as large as, but a little longer than, pigeons’ eggs; equally thick at both ends, but soft, with powdery crystals of carbonate of lime, and therefore differing from the egg of the Alligator, which they resemble in shape, but which has a shell unusually thick and compact. They are found deposited in sand, some six dozen together.[8]
Goldsmith gives a very graphic description of the manner of pursuing and taking the Iguana as a pastime. From his speaking of the Mapou, the Colonial-French for the Eriodendron, or silk cotton-tree, it is probable he derived his account from Father Labat’s amusing notices of tropical natural history. After repeating that its flesh is considered the greatest delicacy of America, he represents the sportsmen of the tropics as going out to hunt this Lizard with the same sort of preparation for success that an English poacher makes for the seizure of the pheasant or the hare. “In the beginning of the season,” he says, “when the great floods of the tropical climates are passed away, and vegetation starts into universal verdure, the sportsmen are seen with a noose and a stick wandering along the sides of the river to take the Iguana. The animal, though apparently formed for combat, is the most harmless creature of all the forest: it lives among the trees, or sports on the water, without ever offering to offend; there having fed upon the flowers of the Mahot (Hibiscus tiliaceus), and the leaves of the Mapou (Eriodendron anfractuosum), that grow along the banks of the stream, it goes to repose upon the branches of the trees that hang over the water. Upon the land the animal is swift of foot; but when once in possession of a tree, it seems conscious of the security of its situation, and never offers to stir. There the sportsman easily finds it, and as easily fastens his noose, round its neck: if the head be placed in such a manner that the noose cannot readily be fastened, by hitting the animal a blow on the nose with a stick, it lifts the head, and offers it in some measure to the noose. In this manner, and also by the tail, the Iguana is dragged from the tree and killed by repeated blows on the head.”[9]
The mode in which the animal is induced to permit the placing of the fatal noose over its head has been described as follows; and we can in some measure confirm its credibility from personal experience, having often captured Dactyloa Edwardsii, and other West Indian Iguanadæ by this very artifice. “They are in the habit of sitting on the branches of trees, facing the sun, with only the front part of their head exposed. On these occasions the following method is resorted to by the huntsman. He approaches gently, whistling as he advances; this attracts the attention of the reptile, and appears to please it, for it advances its head further from its retreat. When the huntsman is come sufficiently near, he gently rubs the end of his pole against the sides and throat of the Iguana, who not only suffers this sort of caress without resistance, but appears to return and enjoy it. The huntsman continuing to employ these means, induces his victim to expose its head sufficiently to allow him to pass a loop, which is fastened to the end of his pole, over the head and round the neck of the reptile; and this accomplished, he brings it to the ground with a violent jerk, and places his foot on its body. The Iguana now proves itself less passive than usual, for when it finds its confidence deceived, and itself captured, it exerts itself with violence, rolls its sparkling eyes, and inflates its throat; but such efforts are useless, the huntsman manages to tie its fore -feet together, and to secure them under the creature's throat, so that it can neither fly nor fight. If taken alive, it appears at first sullen and intractable, but after a time becomes domesticated, and runs about the house and garden with as much confidence as a cat.”
Catesby’s account of the Iguana was probably derived from personal acquaintance with it in the Bahama Islands. He says,—
“These reptiles nestle in hollow trees; their eggs have not a hard shell like those of alligators, but a skin only, like those of a turtle, and are esteemed good food. They lay a great number of eggs at a time in the earth, which are hatched by the sun's heat. The Guanas furnish a great part of the subsistence of the inhabitants of the Bahama Islands; for which purpose they visit many of the remote kayes and islands in their sloops to catch them, which they do by dogs trained up for that purpose, and which are so dexterous as not often to kill them. If they do so, however, the Guanas serve only for present use; if otherwise, they sew up their mouths to prevent their biting, and put them into the hold of their sloop, until they have obtained a sufficient number, which they either carry alive for sale to Carolina, or salt and barrel up for the use of their families at home. These Guanas feed wholly on vegetables and fruit, especially on a particular kind of fungus growing at the roots of trees, and on the fruits of the different kinds of Ananas: their flesh is easy of digestion, delicate, and well tasted. They are sometimes roasted, but the more common mode is to boil them, taking out the fat, which is melted and clarified and put into a dish, into which they dip the flesh of the Guana as they eat it. Though not amphibious, they are said to keep under water above an hour. They cannot run fast, and their holes are a greater security to them than their heels. They are so impatient of cold that they rarely appear out of their holes but when the sun shines.”[10]
Brown, in his “History of Jamaica” (1756), says that the Guana lives for a considerable time without food, and changes its colour with the weather, or the natural moisture of its place of residence. “I have kept,” he adds, “a grown Guana about the house for more than two months: it was very fierce and ill-natured at the beginning, but after some few days it grew more tame, and would at length pass the greatest part of the day upon the bed or couch, but always went out at night. The flesh of this creature is liked by many people, and frequently served up in fricassees at their tables, in which state it is often preferred to the best fowls. When taken young, the Guana is easily tamed, and is both a harmless and beautiful creature in that state.”
In the unpublished MSS. of Dr. Robinson on the Natural History of Jamaica, preserved in the Library of the Jamaica Society, the Iguana is spoken of as familiarly known in that island. After some descriptive notes, he observes,–
“They are said to be inoffensive animals, and meddle with no living creature, unless first attacked, when they bite hard. One of them bit a cat’s paw quite off, that was held to it; and I have seen the above snap at a stick that has been held towards it, with great tokens of wrath, sullenness, and fierceness. They are found in Salt Pond Hills, where they live upon vegetables and fruit; and can by the help of their open toes climb upon trees and shrubs. They hide themselves in holes among the rocks, and are hunted with small dogs by the negroes, who sell them in the towns to many people who admire them as a great delicacy. Their flesh is said to be very white, tender, and well tasted, and even superior to that of a chicken; but for my part I never had an opportunity of tasting this animal’s flesh. The fat is said to be good to cleanse iron utensils with, and preserve them from rust.”
We think it very probable, however, that both these notes of Robinson’s, and those already cited from Brown, belong to the Cyclura, which we know to be an inhabitant of the district mentioned by the former. In another passage, however, it appears to have been a true Iguana, which he speaks of as having been brought from the Isle of Pines, “of a wonderful size, being, as they judged, between six and seven feet in length. . . The hind quarter weighed five pounds, whence they concluded that the Iguana must have weighed twenty pounds.”
Family IV. Agamadæ.
(Agamas.)
The subjects of the present group are by some zoologists (among whom are the great French herpetologists we have so often cited) considered as forming a division of the Iguanadæ; but they are by others elevated to the rank of a Family, and as such we prefer to treat of them. Their most important distinctions are to be found in the teeth; these are entirely wanting in the palate; and those of the jaw, instead of being implanted on its inner side, are seated on the ridge of the jaw-bone, to which they are soldered, and of which they appear to be a continuation.
In the form of the head and of the teeth the Agamadæ resemble the true Lizards, but differ from them in the imbricated scales with which their tails are clothed. The body is for the most part thicker and shorter than the usual proportions; the skin is loose and capable of being inflated with air at pleasure; the head is short, flat, and broad, particularly behind; the neck also is short, and the tail seldom longer than the body. From these peculiarities the Agamas are sometimes called frog-lizards. The whole head, body, and limbs, are commonly covered with lozenge-form or hexagonal scales, which are often prolonged into little spines, which bristle up formidably, when the body is distended with air.
Some of the species, indeed, are so armed with spinous processes of various forms and lengths, as
MOLOCH LIZARD.
to present a truly frightful appearance; such as, for example, the Moloch Lizard of Australia (Moloch horridus).
“Some of the most singular shapes among the existing races of reptiles,” observes Mr. Swainson, “will be found in this Family. The Phrynosoma, with its fat body and short tail, immediately reminds us of a toad. Megalochilus has much of the same shape, but seems to have a large pair of rounded ears standing out from the sides of the head. Those of the sub-genera of Draco are most extraordinary reptiles; the Sitana has an enormous pouch under the throat, which it can swell out so as to appear like a Tetraodon, or porcupine fish. Chlamydosaurus, again, is provided with an immense fringe round the throat, perfectly resembling the broad collars worn by ladies of the present day. The flying lizards (Draco), however, even surpass these, for they possess a distinct pair of wings, attached to the sides of their body, supported by rays, and capable of being expanded or folded at pleasure. These extraordinary reptiles, however, are by no means formidable; they are all of a comparatively small size, live in trees, and feed only upon insects. Of their peculiar habits, however, in other respects, we unfortunately are at present ignorant. There can be no doubt that these wings are used to support them in the air, when leaping from bough to bough, much in the same manner as the loose skin that performs that office among the flying squirrels.”[11]
The Agamadæ are spread over both hemispheres, but are most numerous in the tropical regions of Asia and Africa. They feed chiefly on insects, but some are said to be herbivorous; and seem to affect dry, stony places.
Genus Phrynosoma (Wiegm.).
In this singular genus, whose orbicular form scarcely recals the idea of a lizard, the tail is flattened, and shorter than the body; the whole form greatly depressed; the body nearly globular; the scales on the belly, limbs, and tail, are small and overlapping; those of the upper parts rather larger, and interspersed with longitudinal rows of spines; the hind head is set with large spines.
TAPAYAXIN.
Family V. Varanidæ.
(Monitors.)
These are Lizards of large size, in some respects approaching the Crocodiles. MM. Duméril and Bibron, who designate them by the appellation of Broad-backed Saurians, assign to them the following characters. They have the body very much elongated, rounded, and without a dorsal crest, supported on strong legs and feet, with distinct and very long, but unequal toes. The tail is slightly compressed, and at least twice as long as the trunk. The skin is furnished with enchased scales, which are tuberculous, projecting, rounded upon the head, as well as upon the back and sides, always distributed in rings or circular bands, parallel under the belly and round the tail. The tongue is protractile, fleshy, and similar to that of the Serpents,—that is to say, capable of elongation, and of being withdrawal into a sheath,—narrow and flattened at the base, and deeply divided and separated at the extremity into two points.
They are distinguished from the other Families by evident and easily seized peculiarities. From the Crocodilidæ, in the toes which are all furnished with claws, and never palmated at the base; in the cutaneous tubercles, which are neither square nor furnished with projecting ridges; in the protractile tongue; in the form of the teeth, the pupils, the auditory conduits, and especially in the male genital organs, which are double. From the Chameleonidæ, because their tongue is forked at the point; their eyes furnished with two distinct lids, in addition to the auditory conduits; their body depressed instead of being compressed; and on account of the relative length of their tail, which is never prehensile. From the Geckotidæ, in the form and inequality of the length of the toes, the movements of the tongue, and the presence of movable lids. From the Iguanadæ, in the scales of the trunk, the absence of a dorsal crest, and the vaginal conformation of the tongue. From the Lacertadæ, in the difference of the teguments of the head and body, and the form of the teeth. Finally, from the Chalcididæ and the Scincidæ, in the non-rounded form of the trunk, and the distinct origin of the tail, the structure of the tongue, and especially in the form and disposition of the scales.
The teeth of the Varanidæ are always flattened at the root, which is lodged in the length of a
UNDER JAW OF MONITOR.
furrow constituting a common alveolus or socket, having no internal border. The crowns or free portions of the teeth are most commonly pointed and curved backwards. There are no teeth in the palate. The neck is longer in proportion than in other Lizards, which gives them an unusual aspect.
The whole surface of the body is covered with tubercles, which do not overlap, but are most frequently arranged in transverse series. Some species have the scales of the back set with a ring of small projecting points, the regularity of which is highly ornamental. Those of the lower parts are flat, lengthened, and somewhat six-sided. There is no collar of great scales beneath the neck, but there is a transverse fold of the skin.
The colours of these Lizards vary from black to green more or less deep, with spots which seem to depend on the tubercles, the tints of which, variously grouped, present more or less regular designs, resembling Mosaic work; so that the skin of the Monitors may be employed in the arts like shagreen.
The tongue, unlike that organ in the Families we have described, is fleshy, and very extensile, so that it can be thrown forth to a length double that of the head. The greater part is cylindrical, but the terminal fourth is split into two conical, horny, very flexible points. When retracted, more than half the length is encased in a sort of sheath; and the portion that remains exposed is frequently tinged with bright colours, so as to be easily distinguished by its hue, even when not protruded.
The Monitors are found in both hemispheres; and with the exception of Europe and North America, neither of which have any, the species are equally divided among the great divisions of the globe: viz., four in Africa, four in Asia, four in Australasia, and four in South America.
These are divided into two groups, the terrestrial and the aquatic Monitors, the habits of which differ much from each other. The former have the tail conical and nearly round, and these live in sandy districts or among dry rocks, never frequenting water. They run with rapidity, with a serpentine motion, a mode of progression produced by the long and muscular tail, which helps to push them forward, and aids them in leaping on the prey which they pursue. Some of these were known to the ancients, who regarded them as terrestrial Crocodiles, probably from their size and ferocity.
The aquatic Monitors, which are by far the more numerous, have the tail, which is very muscular and strong, compressed through its whole length; it thus forms a powerful organ of progression in swimming, especially as its upper surface is frequently surmounted with one or two rows of flattened scales forming an elevated crest. These frequent the banks of lakes and rivers, which they traverse by swimming, and into which they are said to drag their living prey, when they have seized it, in the manner of the Crocodiles.
The food of the Varanidæ consists, it appears, of any animals which they have size and strength sufficient to overcome. The terrestrial species hunt after large insects, such as cockroaches, locusts, and beetles; the eggs of ground-building birds, and small vertebrate animals. The aquatic species are still more formidable, for, besides fishes, tortoises, chameleons, and the eggs of birds and of crocodiles, they are said to prey on quadrupeds of considerable size and strength. M. Leschenault de Latour asserts that they associate in bands, and watch at the margins of the rivers to attack quadrupeds that come to quench their thirst; and that he has seen them attack a young stag as he attempted to swim across a river, in order to drown him. He even declares that he found the thigh-bone of a sheep in the stomach of one which he dissected. Inhabiting, in many cases, waters which are likewise tenanted by Crocodiles and Alligators, they are vulgarly believed to be beneficial to mankind by giving warning of the proximity of these much-dreaded creatures. This, it is asserted, they do by a hissing, or whistling sound; and though, probably, having little foundation in truth, this reputation has procured them the names of Monitors, Sauvegardes, &c., and has caused them to be regarded with a measure of popular respect.
Genus Varanus. (Merr.)
The scales of the body in this genus are set side by side in the skin, and are each surrounded by a ring of small and close-set tubercles: the upper edge of the tail is more or less sharp, and there is a fold beneath the neck, passing transversely in front of the breast.
We illustrate the terrestrial Monitors by the White-throated Varan of South Africa, (Varanus albogularis, Kuhl,) a species the locality of which was unknown, till it was met with by Dr. A. Smith in his late zoological expedition into the interior of that continent. Though he did not obtain any specimens of this Lizard south of Latakoo, yet there is reason to believe that it has been occasionally seen within the limits of the Cape Colony; and the Doctor supposes that it is the reptile which is called das Adder by the Boors, and which is so much dreaded from its reputed venomous qualities.
The specimen from which Dr. Smith’s description was taken was no more than two feet eight inches in length; but specimens occur which have attained a size nearly double of this. The ground-colour is yellow, variously banded, blotched, and spotted with brown, so as to produce a rich and beautiful effect.
WHITE-THROATED VARAN.
The enterprising zoologist who discovered this reptile thus describes its manners:—“It is usually met with in rocky precipices, or on low stony hills, and, when surprised, seeks concealment in the chinks of the former, or in the irregular cavities of the latter; and when any irregularities exist upon the surface of the rocks or stones, it clasps them so firmly with its toes, that it becomes a task of no small difficulty to dislodge it, even though it can be easily reached. Under such circumstances the strength of no one man is able to withdraw a full-grown individual; and I have seen two persons required to pull a specimen out of a position it had attained, even with the assistance of a rope fixed in front of its hinder legs. The moment it was dislodged it flew with fury at its enemies, who by flight only saved themselves from being bitten. After it was killed it was discovered that the points of all the nails had been broken previously, or at the moment it lost its hold. It feeds upon frogs, crabs, and small quadrupeds; and from its partiality to the two former, it is often found among rocks near to springs or running streams; which fact having been observed by the natives, has led them to regard it as sacred, and not to be injured without danger of drought."[13]
Genus Teius. (Merr.)
This limited genus of large Lizards is by some zoologists made the type of a separate Family; but they seem to have so many affinities with the Monitors of the Old World as to be rightly associated with them. In many of their habits they agree with the aquatic forms we have just described, and partake of a similar name and reputation, being commonly known as Sauvegardes.
The scales of the back are small, angular, smooth, not overlapping, disposed in transverse bands; those of the belly are flat, four-sided, longer than broad. The tail is rounded, but somewhat four-sided, a little compressed towards the tip. The skin of the throat and breast forms two or three transverse folds. There are femoral pores. The head is covered with large plates or shields: the palate is destitute of teeth; those of the jaw are notched at the summit; the tongue is very long, capable of great protrusion, sheathed at the base, and divided at the tip into two long and slender filaments.
The Sauvegardes are Lizards of imposing appearance; they are stoutly built, and richly coloured; being marked with spots of rich yellow on deep black, or vice versâ.
These Lizards are natives of the tropical parts of America. They attain a considerable size, frequently measuring four or five feet in length. According to MM. Duméril and Bibron, they generally inhabit the fields and borders of woods, but never climb trees; they appear also to frequent sandy arid tracts, and it is said they excavate burrows, in which they lay themselves up for the winter. Sometimes, in their efforts to elude pursuit, they come upon a lake, pond, or river, when, as we are informed by D’Azara, in order to avoid the danger that menaces them, they plunge in and do not leave the water till all fear of harm is past. These Lizards have not indeed webbed feet, as MM. Duméril and Bibron observe, but under these circumstances their long and compressed tail becomes without doubt a sort of oar, which well answers their purpose. D’Azara states that they feed on fruits and insects, as well as on toads, serpents, young chickens, and eggs; also that they are fond of honey; and that in order to procure it without fear of the bees, they come forward at intervals, and each time as they run away, they give the hive a blow with their tail, till by repeated attacks they weary out the industrious insects, and drive them from their home.[14] It is not certain that the Sauveguardes are frugivorous; but there is no doubt that they feed on insects, for MM. Duméril and Bibron found remains of them in the stomachs of all the individuals which they opened. In one they found the fragments of Coleoptera and the remains of caterpillars; in another, portions of skin and bones which had certainly belonged to a common Ameiva.
But two species of this genus are recognised, of which we select for illustration the Teguixin (Teius teguixin, Linn.), as the longest and best known. It is well figured in Madame Merian’s splendid but not always faithful plates on the insects, &c., of Surinam, whence some naturalists, in honour of that lady, have distinguished the species by her name Monitor Merianæ.
This noble Lizard is reported to attain the length of four or even five feet, and a thickness proportionate. Its ground-colour is a deep velvety black, beautifully varied with rich yellow spots, sometimes irregularly scattered, sometimes arranged in transverse bands, and sometimes in two longitudinal stripes running the whole length of the body. The face and whole under parts are yellow banded with black, and the posterior half of the tail is ringed with alternate bands of the same colours.
The Teguixin is spread over the greater part of South America, from Guiana to Brazil; it is also attributed to the West Indies, but we think erroneously, though it may possibly occur in
TEGUIXIN.
Trinidad. Our knowledge of its habits is principally derived from the great naturalist of South America, D’Azara. He asserts that though it readily takes to the water as a refuge from danger, it does not swim, but sinks and walks along at the bottom. It fights with resolute courage when attacked or captured, biting with great severity and maintaining its grasp with inflexible pertinacity. It manifests much ferocity also in the seizure of its animal prey. Its flesh is eaten, and highly esteemed; nor are its excellences esteemed only by the epicure; for a medical value is attached to rings of the skin stripped from its tail, which are worn by the simple natives of those regions as preventives of paralysis, and curatives of painful humours.
Family VI. Lacertadæ.
(Lizards.)
The two species which constitute the only British representatives of the vast Saurian Order are members of this Family, which is known by the following characters:—
The body is long, slender, and elegant, without spines on any part; the toes are free, long, and very unequal; the tongue long, extensile, sheathed at the base, and terminating in two long slender points; there is a collar round the neck, formed by a transverse range of broad scales, separated from those of the breast by a space covered with minute ones, and overlapping them; a part of the bones of the skull projects over the temples and orbits; the palate is in general furnished with minute teeth, and those of the jaw are placed on the same line, and have a cutting edge.
The upper parts of the body are covered with small overlapping scales; the top of the head and the temples are covered with broad plates or shields, of various but regular forms, the margins of which are in contact. On the slight variations of form or relative position in these plates, generic distinctions often rest, and hence, for the sake of perspicuity in description, these have received names, which we here enumerate, copying the accompanying illustration from Professor Bell's beautiful work on British Reptiles.
HEAD OF LIZARD.
The plate marked 1 is termed the rostral; 2, the nasal; 3, internasal; 4, fronto-nasal; 5, frontal; 6, anterior palpebral; 7, posterior palpebral; 8, frontoparietal; 9, inter-parietal; 10, parietal; 11, occipital.
The scales of the tail, which are arranged in distinct rings or transverse bands, are long and narrow, especially towards the tip of this organ. The lower parts of the body are clothed with broad plate arranged lengthwise in several rows; not overlapping, but in contact at their margins.
The femoral pores, which we have before mentioned, either as present or absent, in other Saurian groups, are always found in the Lacertadæ. "They consist, probably," observes Professor Bell, "of very small follicular glands, each placed in a scale, the middle of which is pierced by the opening of the follicle. In some, the scale is very little larger than the pore, and appears almost like a minute tube; in others, the scale is larger and triangular. The use of these pores is not known. They vary exceedingly in number, even in the same species: in this respect, therefore, they afford no distinctive characters."
FEMORAL PORES OF AMEIVA.
The Lizards are confined to the Old World, where the species are numerous. None of them attain a large size, but the colours of most are elegant and beautiful, and some shine in the most gem-like radiance of green and gold. Their graceful slender forms, rapid motions, and gay tints, associated with the fairest weather of summer, and the sunniest spots of the country, cause them to be generally looked upon not only without alarm, but even with admiration; and, we may add, that there is an expression so meek and gentle in the countenance of the Lacertæ, that physiognomy would be greatly at fault if it were found connected with poisonous fangs, or ferocious propensities. Indeed their bright eyes as they timidly peep from under the overhanging leaves, and the rustling that their fleet steps make as they dart away among the herbage, are felt to be as poetical accompaniments of rural scenes as the flowers and the birds. Thus Byron says,—
" The green hills
Are clothed with early blossoms; through the grass
The quick-eyed Lizard rustles, and the bills
Of summer-birds sing welcome, as ye pass."
And Moore, whose poetry so faithfully reflects the beautiful in nature, speaks of
"Gay Lizards glittering on the walls
Of ruin'd shrines, busy and bright,
As they were all alive with light."
Genus Zootoca. (Wagl.)
The distinctive characters of this genus are the following. The throat is furnished with a distinct collar; the nostrils are placed near the outer and lower margin of the nasal plates; there is a bony plate over the orbits; the temples are covered not with plates, but with close-pressed scales; the scales of the back are lengthened and six-sided; the palate is destitute of teeth; the femoral pores are small and round, so as almost to form tubes. The young are produced alive; the membrane of the egg, answering to the shell, being ruptured either immediately before, or in the moment of, birth.
The most common of our native Lizards is of this genus, the Nimble or Viviparous Lizard (Zootoca vivipara, Jacq.), whose history Professor Bell thus pleasingly records:—
"This agile and pretty little creature is the common inhabitant of almost all our heaths and banks in most of the districts of England, and extending even into Scotland: it is also one of the few reptiles found in Ireland. On the continent its range does not appear to be very extensive: it is not found in Italy, nor, I believe, in France, and is very probably confined in a great measure to our own latitude. Its movements are beautifully gracile as well as rapid;
VIVIPAROUS LIZARD.
it comes out of its hiding-place during the warm parts of the day from the early spring till autumn has far advanced, basking in the sun; and turning its head with a sudden motion the instant that an insect comes within its view, and darting like lightning upon its prey, it seizes it with its little sharp teeth and speedily swallows it. Thus it will often take a great number of the smaller insects, preferring those of the dipterous order; though it will not refuse many of the coleoptera or orthoptera, if they be not too large.
"Instead of depositing her eggs in the sand to be hatched by the warmth of the sun, the female of the present species retains the eggs within the oviduct until the young are ready to leave them, and they are produced alive. As in all the ovo-viviparous reptiles, the covering of the egg is very thin, and merely membranous. In this respect they differ from those which deposit their eggs before the embryo is formed. In the latter case a more efficient protection is necessary, and the covering is either calcareous, as in the Tortoises and Crocodiles, or of a substance resembling parchment, as those of the Snakes and most Lizards. In the Viper, which also produces its young alive, the covering, as in the present animal, is extremely thin and very easily torn; and there is reason to believe that the laceration of this membrane and the emancipation of the young take place in, and are occasioned by, the very act of parturition.
"As the young ones are occasionally found with the mother, there is some reason to believe that these little animals are not wholly devoid of the instinct of parental care and tendance; but it is scarcely probable that the exercise of this feeling is ever very powerful, or that it endures for any considerable period. The young, when brought forth, are fully formed and capable of running about, and very shortly afterwards of taking their own food. The usual number is from three to six.
"Although I have alluded to the sun's influence as being the means of hastening the evolution of the embryo in the oviparous reptiles, it is not to be concluded that the same source of warmth is unnecessary in the present and similar instances. The only difference is, that in the ovo-viviparous species the solar heat is communicated to the embryo through the medium of the mother; and hence we often see the pregnant female, about the month of June, constantly basking in the sun, and lying in such a position as to expose the body most fully to his influence. Every one who has watched the habits of our native reptiles must have seen the same circumstance in the gravid female of the Common Viper, and may have observed how much more reluctantly and tardily she leaves the genial spot than the male."[15]
Mr. W. C. L. Martin also thus speaks of the agile movements of this pretty and familiar little reptile:—"It is astonishing to see how rapidly, when alarmed, these agile little creatures gain their burrows, or disappear from view, diving beneath the intertangled vegetation: they seem gone in the twinkling of an eye. Not less prompt and rapid are they in catching their prey; the moment an insect comes near them, or settles on a leaf within due distance, their bright eyes mark it; the next instant it is seized and swallowed: the act is wonderfully quick and instantaneous. The sight of these animals is indeed very acute, and their hearing appears also to be by no means deficient; we have seen them on the slightest noise, on the snapping of a branch, or a rustle made among the leaves, dart off to their burrows, and after a little time cautiously make their re-appearance, and on the least alarm again seek refuge in their retreat."[16]
Few persons can have paid any attention to these reptiles without having been struck with a phenomenon which, when observed for the first time, seems singular in the extreme,—the facility with which the tail breaks off on the slightest violence. We well remember the astonishment with which we first witnessed the circumstance, and the painful feeling of compunction with which we regarded the writhing fragment left in our fingers, with its white projecting muscle, slightly bleeding, and thought of the involuntary mutilation that we had committed. We were not then aware of the rapidity with which the lost organ would be reproduced.
Dr. Drummond has described his surprise at a similar incident:— "Being on the sea-shore at Pulo Bay, in Sardinia, and searching for specimens of natural history, I observed a large Lizard running for shelter under a heap of stones. I was just in time to seize it by the end of the tail, but suddenly the resistance made by the animal to my attempt to drag it from its hiding-place ceased, and I gave it up for lost; but I as suddenly had cause for alarm myself on seeing what appeared to be a small Snake leaping with great agility about my feet, and springing as high as my knee. I instantly started out of its way, and watched it at a respectful distance, when I found that it was the tail of the animal, which I was not before aware could so easily separate."[17]
This singular phenomenon is doubtless dependent on a peculiarity of structure no less singular, first noticed by Cuvier. That illustrious physiologist considers it a very interesting fact that a great number of the vertebræ of the tail in the common Lizards are divided in the middle in a vertical plane into two portions; and that these portions are separated with even more facility than two contiguous vertebræ at the point of articulation; and this for the simple reason that the articulation is complicated, formed of many irregularities of surface (apophyses), and strengthened by ligaments, while the adhesion of the two parts of each vertebra is retained only by the continuous periosteum (or membrane that invests the bone), and by the surrounding tendons. This structure he had observed besides in the Iguanæ and the Anoles, and is of opinion that it would be found in all the genera which, like those mentioned, are subject to the rupture of the tail. "Every one knows," adds this anatomist, "that the tail shoots out again after having been broken, but neither the skeleton nor its integuments are, in that case, the same as before the rupture. The scales of the skin are generally small, without ridges and without spines, though they may have had the contrary qualities in the original tail; and internally, instead of the numerous vertebræ, with all their apparatus of apophyses and ligaments, there is nothing but a long cartilaginous cone of one piece, which only presents annular wrinkles, numerous indeed, but scarcely at all elevated." We have some reasons for thinking, however, that in time the reproduced tail would assume at least the exterior appearance, if not the interior structure of the original member.Like most of the tribe, the Viviparous Lizard varies considerably in its colours and markings. The most common variety is of an olive hue, with a line of dark brown down the back, and a band of the same down each side, with rows of black spots between; the under parts are, in the male, bright orange, spotted with black,—in the female pale greyish-green, without spots. Six inches is the average length of the adult male.
Family VII.—Scincidæ.
(Snake-Lizards.)
There is not perhaps in the whole circle of zoology, a more beautiful example of the gradation between forms whose extremities are widely distinct from each other, than is presented by the gradual and almost imperceptible transition of the Lizards into the Serpents. If we look at a Chameleon, or an Iguana on the one hand, and then at a Rattlesnake or a Cobra di Capello on the other, they seem almost as remotely separated as animals of the same class can be; and yet so minute are the steps by which we are led from one to the other, that it is impossible with any satisfaction to draw a line that shall divide them, other than such as is merely conventional and arbitrary. Pressed by this difficulty, while some zoologists, as Mr. Gray, separate the Lizards from the Serpents by a third order, called Saurophidia, constituted expressly for the reception of these intermediate and transition forms, others, with Merrem have preferred to consider the whole of the scaled reptiles as forming but a single Order.
Some of the steps of this beautiful gradation, by which the four long-toed and muscular limbs that mark the Lizard pass away, and leave no trace in the lithe cylindrical Serpent, are thus graphically enumerated by Professor Bell. "From the well-known family of the Scinks (Scincidæ), with their true legs and five-toed feet, down to the Slow-worm (Anguis fragilis) and its immediate congeners, every possible gradation is to be found in the development of the anterior and posterior extremities. Agreeing, as they all do, in the Saurian character of the structure of the head, the consolidation of the bones of the cranium and jaws, and the narrow and confined gape, so different from those parts in the true Serpents, they yet approach the latter in the comparative length of the bodies, and in the gradual diminution and ultimate disappearance of the extremities. In the genus Scincus, for instance, the limbs are already less robust than those of the true Saurians; the two pairs are also more distant from each other, in consequence of the greater comparative elongation of the body. There are as yet five perfect toes on each foot, which, however, are shorter and more even in their relative proportions than in the true Saurians. These deviations become increased in the genus Chalcides, and still more in Seps, which has a very elongated body, the limbs extremely small, and the toes only four or three on each foot. In Monodactylus a further reduction takes place in the development of the limbs, which have dwindled to a mere little undivided finger; they are still, however, four in number; but in the genus Bipes the anterior ones have wholly disappeared, and are found in a rudimentary state under the integument, the posterior ones constituting only small undivided processes. These also being removed, the Ophidian form of the present genus, [Anguis] and those of Tortix, Typhlops, and others, with all the Amphisbænidæ, succeed, in which the bones of the shoulder, the sternum, and the pelvis, exist in a more or less rudimentary condition; and lead us towards the true Snakes, in which all these parts are lost, excepting the rudiments of a posterior extremity, which in the Boa appears externally in the form of a small horny hook, or holder, on each side of the vent. In the Serpents, the gape, too, has assumed its extreme power of extension, from the bones of the jaws and other parts of the face being separate; and in most of them the scales, which in the former groups were similar on the upper and under parts of the body and tail, are small and imbricated above, whilst beneath they assume the form of broad transverse plates."[18]
The Scinks have the head covered with large horny plates, of angular forms, in contact with each other at their edges, with the sutures or divisions always distinct: the neck is of the same size as the breast; the body and limbs are clothed with scales, more or less angular, frequently wide, with a somewhat rounded edge, disposed in quincunx (or like the meshes of a net), and overlapping each other, much like the scales of a fish. The back is rounded, without any crest; the belly is also more or less rounded, and covered with scales similar to those of the back. The tongue is free, fleshy, not very thick, slightly notched at the tip, and covered either totally or partially with scaly papillæ.
Thus the Scincidæ are at once distinguishable from all the Saurian Orders, except the Lacertadæ, by the broad plates which cover the head; and from the latter by the belly being clothed with scales not diverse from those which cover the rest of the trunk.
HEAD OF GALLY-WASP.
The Scinks are a harmless race, for the most part living upon insects, slugs, and worms; but one of the most typical species, the great Gally-wasp of Jamaica, we have found to feed on fruits and other vegetable substances. Of their reproduction little seems known, but as the Gally-wasps, the Mabouyas, and the Slow-worm are viviparous, perhaps the same is true of the whole Family. They are commonly agile creatures, and the shortness of their limbs, and the smoothness of their scales, enable them to glide through small apertures with facility.
The geographical range of the species is very wide, they being spread, as MM. Duméril and Bibron observe, over nearly the whole surface of the globe, for they are found in very high latitudes, even in countries where the lowness of the temperature would seem to forbid the existence of Reptiles; thus the Slow-worm (Anguis fragilis), for example, is found as far north as Sweden, and perhaps farther. Their geographical distribution is otherwise remarkable. Europe does not possess a single species which is peculiar to itself, for though seven species are found there, they are all shared with Africa, and two of them also with Australia and Polynesia. Africa, besides these, has eighteen of its own; seventeen are peculiar to Asia, and three others it shares with America or Polynesia. Sixteen species are American, but one of these is also Asiatic, and another is cosmopolite. Australia and Polynesia are the regions richest in the Scincidæ, for they possess forty species, four only of which are common to other divisions; and it is remarkable that all the other Saurian Families are comparatively deficient there.
Genus Celestus. (Gray.)
The nostrils in this genus open on the sides of the muzzle, in the nasal plate; the tongue is notched at the tip, clothed with papillæ, which are scale-shaped in front, and slender or bristle-shaped behind; the teeth are conical or rounded; the palate is not furnished with teeth, but is furrowed lengthwise; the muzzle is somewhat obtuse; there are four feet, each terminating in five unequal toes, which are compressed, not toothed at their edges,
SCALE OF GULLY-WASP.
and furnished with claws; the palms and soles of the feet are set with tubercles; the tail is conical, or slightly compressed, and sharp-pointed; the scales are marked with numerous striæ, or delicate lines.
One of the largest species of the Family is the Gaily-wasp of Jamaica (Celestus occiduus, Gray), which grows to about two feet in length, and nine inches in circumference. Its head is large, and somewhat triangular, being pointed at the muzzle and swollen at the occiput; the legs and feet are very small, but perfectly formed. Its hue is pale yellow, irregularly spotted and dashed with brown, but the head is black.
The Gaily-wasp inhabits marshy lowlands in the island above named, where it forms burrows in the soft earth by means of its short paws. These excavations resemble those of the Land-crab (Gecarcinus ruricola), but are deeper and more tortuous. The animal is nocturnal, rarely coming forth till after the heat of the day has begun to abate. It is not very timid, but will sit in the mouth of its hole, and retracting the skin of its lips, show its teeth at an intruder like a dog. Great dread is entertained of the bite of this reptile, which is held to be venomous. That its muscular powers are great, there is no doubt, and that its blunt teeth would painfully bruise the flesh, and produce an injury perhaps more difficult to be healed than even a lacerated
GALLY-WASP.
wound, is not improbable. With all our inquiries made in the island, we have never been able to trace any direct accounts of serious mischief done by this animal; and those which seemed most circumstantial of second-hand narratives are such as in a great degree may be accounted for by the imagination,—the fears of the patient, in the case of a bite, being very highly excited. The creature is acknowledged, however, to be inoffensive, biting only in self-defence, when accidentally trodden on, or attacked.
In the stomachs of such individuals as we have dissected, we found only vegetable food; fragments of large fruits, bitten off but not masticated; and the soft white bases of the spongy leaves of bulrush were conspicuous. The flesh has been cooked and eaten by those who could overcome the general aversion with which the animal is viewed, and it was found to be excellent.
The female brings forth her young alive; these are numerous, for we have taken seventeen young, perfectly formed and nearly ready for the birth, from the body of one mother. These were about five inches in total length, of which much more than half belonged to the tail, a proportion very different from that of the adult.
Genus Anguis. (Linn.)
The great disparity of form which we have already alluded to between the genera of the Family before us, induces us to select two examples for its illustration. In the genus Celestus, the limbs, though small, are perfectly formed, and furnished with the full number of perfect toes; the body is thick and stout, and the whole appearance Lizard-like. In the genus Anguis, there is not the slightest appearance of any external limbs, the body is very long, slender, and cylindrical, and the whole appearance is Snake-like. Indeed so completely is this the case, that not only by unscientific observers, but by such men as Linnæus, Cuvier, and other illustrious zoologists, the Slow-worms have been arranged with the Serpents. Yet the agreement is merely superficial; they certainly form, as already remarked, a beautiful and interesting link between the Lizards and the Snakes; but their whole anatomical structure, and other peculiarities manifest that their true affinities are with the former rather than the latter.
The technical characters of the genus Anguis are as follows: the body and tail are cylindrical and obtuse; the scales are smooth, overlapping,
Head of slow-worm.
nearly equal on the upper and under parts; the head is covered with about nine larger plates; the drum of the ear (tympanum) is concealed beneath the skin, but communicating with the air, according to MM. Duméril and Bibron, by a minute linear orifice; the teeth of the jaws are hooked and compressed; there are none on the palate; the eyes are furnished with three lids; there is no Head op slow-worm, external trace of limbs, but the bones of the shoulders and of the pelvis exist in a rudimentary form.
The common Slow-worm (Anguis fragilis, Linn.) is often called the Blind-worm, from the minuteness of its eyes, which are, however, sharp and brilliant. The former appellation refers to the sluggishness of its movements, and the specific term fragilis, to the brittleness of its body, when the muscles are contracted from sudden fear. If laid hold of and pursued, instead of attempting to escape or to defend itself, it contracts itself to such a degree of rigidity as to be easily snapped in two.
Twelve inches may be considered the average length attained by this reptile, though it has been known considerably longer. It is nearly of equal thickness throughout, but rather more slender towards the tail, the tip of which is abrupt. The colour is brownish grey, with a silvery gloss;
SLOW-WORM.
several rows of obscure dark dots run down the sides, and a black line down the middle of the back. In some varieties, however, these marks are scarcely visible. The under-parts are bluish-black.
The Slow-worm is spread over nearly the whole of Europe, from Sweden and Russia to the shores of the Mediterranean: it is found in the Swiss Alps at an elevation of nearly 6000 feet; it is well known in every part of Great Britain, but has not been found in Ireland. With the common propensity to attach venomous qualities to all reptiles, the vulgar in our own country suppose the inoffensive little Slow-worm to be highly poisonous, and this false notion is shared by many whose powers and opportunities of observation should have taught them better. Shakspeare talks of it as "the eyeless venom'd worm," and speaks of "the blind-worm's sting" among the horrors which are to be boiled "i' the charmed pot" of the witches. Dr. Borlase, as cited by Pennant, speaks from hearsay of a man in Oxfordshire who had lost his life by the bite of a Slow-worm, which, however, the reptile could not have been, from the description which he himself gives.
No animal, in fact, can possibly be more harmless than the vilified Slow-worm. "Even when handled roughly," observes Professor Bell, "it rarely attempts to bite; and when it is irritated so as to induce it to seize upon the finger, the teeth are so small as scarcely to make an impression."
Like all the other reptiles that inhabit these islands, the Slow-worm retires to a place of security on the approach of winter, which it passes in a state of insensibility. Sometimes it contents itself with hiding under a compact mass of decaying leaves in a sheltered situation, but more commonly it penetrates into the soft earth, where it is covered with heath or brushwood, forming burrows by means of its smooth muzzle and polished body, to the depth of three or four feet, describing in its course "different circuits, and having several issues." It comes forth earlier in the spring than any other of our Snakes or Lizards; but Lacépède asserts that it continues to live in its burrow, coming up to obtain air and food, when it raises its head out of its hole ready to retreat on any alarm. "Even in the winter," says Mr. Martin, "it sometimes does this, though snow may be on the ground, if the sun be shining with a warm though transient gleam."[19] In summer it may frequently be seen on sunny banks and beneath hedges, enjoying the warmth and basking in the genial beam: it is easily captured, and as easily killed, for its fright produces the rigid brittleness already described, instead of quickening its efforts to escape.
The food of the Slow-worm must of necessity be very small, for the mouth not being dilatable, as in the true Snakes, it cannot possibly receive such prey as Frogs, Toads, and Rats, which have been absurdly assigned to it. Professor Bell has found insects in its stomach, and M. de Sept Fontaines asserts that it will readily feed on earth-worms, even of six or seven inches in length. But yet another prey seems to be still more acceptable, according to the following very interesting note by Mr. Daniel.
"A Blind-worm that I kept alive for nine weeks, would, when touched, turn and bite, although not very sharply: its bite was not sufficient to draw blood, but it always retained its hold until released. It drank sparingly of milk, raising its head when drinking. It fed upon the little white slug (Limax agrestis, Linn.) so common in fields and gardens, eating six or seven of them, one after another; but it did not eat every day. It invariably took them in one position. Elevating its head slowly above its victim, it would suddenly seize the slug by the middle, in the same way that a ferret or dog will generally take a rat by the loins; it would then hold it thus sometimes for more than a minute, when it would pass its prey through its jaws, and swallow the slug head foremost. It refused the larger slugs, and would not touch either young frogs or mice. Snakes kept in the same cage took both frogs and mice. The Blind-worm avoided the water; the Snakes, on the contrary, coiled themselves in the pan containing water which was put into the cage, and appeared to delight in it. The Blind-worm was a remarkably fine one, measuring fifteen inches in length. It cast its slough whilst in my keeping. The skin came off in separate pieces, the largest of which was two inches in length; splitting first on the belly, and the peeling from the head being completed the last."[20]
For some other details of the history of this little reptile, we quote Professor Bell, from whose elegant work on British Herpetology, most of the above particulars have been gleaned. "One very interesting point in its habits, is its being ovo-viviparous. Like the Zootoca vivipara, the young of this animal are hatched before they come into the world, and it is probable that in this case, as in that of the species just named, as well as in the Viper and the Rattlesnake, the rupture of the membrane of the egg takes place during parturition. The female is said to go with young about six weeks or two months: there can be no doubt, however, that the duration of this period must depend upon the temperature to which the animal is exposed. They are produced in June or July. The number of young ones produced at one birth varies from seven to twelve or thirteen. When brought forth, they are from eighteen to twenty-two lines in length. The young become very active almost immediately after their birth, and soon learn to feed upon small soft insects, and probably small worms, snails, or slugs.
"The shedding of its skin is performed by this species in the same manner as by most of the true Ophidians. It is, in fact, taken off in one piece, when the animal is at liberty and strong enough to effect this; and, like the others, it leaves its skin turned inside out, attached to the brushwood, or other substance which it has employed to entangle or secure it as it was coming off. It is, however, stated, that in some cases it is inverted only as far as the vent, and that the tail slips out of its covering 'like a sword out of its scabbard.'"[21]
- ↑ British Reptiles, Introd. xx.
- ↑ "These most singular creatures are particularly remarkable for the diminished sympathy of the two sides of their whole frame, one of which may be asleep and the other awake, one of one colour and the other of another, &c.; the separate movement of their eyes being merely another phase of the same phenomenon. Hence it is remarkable, that unlike most other animals, the Chameleon is totally unable to swim, from the incapability of its limbs of acting in due concert."—Blyth's Cuvier, 278.
- ↑ Ann. des Sci. Nat.; 1834.
- ↑ Penny Cyclop., xi. 102.
- ↑ The apparatus by which this extension is effected was thus described as long ago as 1825, by Professor Bell. “The framework of this structure consists of a remarkable developement of the os hyoides or bone of the tongue. This bone is situated immediately under the larynx. It has two long, slender, bony processes on each side, which, for the sake of distinction, I shall term the anterior and posterior lateral processes,—a small one which is filiform, given off from the anterior part of the bone, and closely connected with the under part of the tongue,—and a very long, delicate, and elastic cartilage, extending from the body of the bone, nearly to the middle of the abdomen, immediately beneath the skin, to the internal surface of which it is attached by condensed cellular tissue. In its form it is slightly flattened and tapering to its extremity, where it is extremely slight and flexible.
“The anterior lateral process extends backwards to the angle of the lower jaw, over the muscles of which it is curved upwards. The posterior lateral process is placed in a similar direction, but does not take the same curve over the edge of the jaw. These two processes run parallel to each other through almost their whole length, but at a small distance apart.
“There are several pairs of muscles attached to these little bones, by the action of which the phænomena are produced, which it is my object to explain. Of these the following are the principal. A broad strong muscle arises from the whole edge of the posterior lateral process, and is inserted into the clavicle. It is consequently of considerable length; and by its contraction the whole bony frame- work is drawn back and a little downwards, so that the distance between the two extremities of the long elastic cartilage being diminished, this organ is thrown into a curve, and the skin of the throat and belly is stretched upon it, exactly as the silk is strained upon the whale-bone ribs of an opened umbrella. The parts are restored to their natural state by the action of [counteracting] muscles.” (Zool. Journ. ii. 12.) - ↑ “British. Reptiles.” Intr. xx.
- ↑ Dum. et Bibr.
- ↑ At Aritaka, on the Essequibo, Schomburghk relates that south of the rapids, numerous sandbanks rising out of the water serve as a depository for the eggs of the Guana; in a very short time they took some hundreds.
- ↑ “Animated Nature,” book ii., chap. 3.
- ↑ “Natural History of Carolina,” &c.
- ↑ “Classification of Reptiles,” ii. 161.
- ↑ “Penny Cyclop.” i. 193.
- ↑ Illust. Zool. S. Afr.
- ↑ This sagacity seems somewhat apocryphal.
- ↑ Brit. Rept. 34.
- ↑ Pict. Museum, ii. 94.
- ↑ First Steps to Anatomy, 86.
- ↑ Brit. Reptiles, 40.
- ↑ Pict. Mus. ii. 99.
- ↑ White's "Nat. Hist. of Selborne" (Bennett's edit.)
- ↑ Brit. Rept. 44.