CHAPTER XVII.

MARVELOUS CREEPING ANIMALS.

Reptiles of Antiquity-Animal Curiosities-Fangs of Deadly Poison-Strange Mode of Breathing-Historic Chameleon-Shooting Tongue-Changing Colors-Two Animals in One—A Creature Asleep on one Side and Awake on the Other— Five-Toed Geckos-Curious Suction Foot-Nimble Running on Smooth Surfaces-Tongue like a Dart-The Common Iguana-South American Reptile— Pouch Under the Jaw-Hunting the Iguana-Lizards for Breakfast-Darwin's Description of the Iguana-The Sea Guana-Attachment of Male for FemaleA Gallant Defender-Capital Swimmers-Bellowing Bull-Frogs-Frogs Giving First Idea of Electric Telegraph-Housed in Winter Quarters-Stories of the Domesticated Frog-How a Frog Disappeared and what Became of Him-Wonderful Horned-Frog-The Mysterious Salamander- Old Notions about a Creature that could Resist Fire-Human Clothing that will not Burn-Land Tortoises-Finely Colored Shells-Remarkable Longevity-Elephantine TortoiseHow the Tortoise Feeds-Astounding Surgical Operation-Value of the Tortoise Shell--The Tun Snail-A Creeping Oddity.

IN acquaintance with reptiles may be traced backwards to a very remote period. The sacred Scriptures, especially those of the Old Testament, have numerous passages alluding to them; and the ancient monuments of the Egyptians prove that the great groups of the tortoises, the lizards, the serpents, and the frogs were well known to that people. Those forms of animal life must, therefore, have attracted attention from the earliest times; while a natural desire to ascertain which of them were dangerous must have led to particular inquiry, in order to solve the doubt. It is evident, moreover, from the ancient writings of Athenæus, as well as of Herodotus, the father of history, and the contemporary of the prophet Malachi, that notions not merely vague but precise were entertained respecting many species of reptiles.

Reptiles form, unquestionably, a most remarkable class of animated beings. Some are of strange and uncouth aspect, and others, resplendent with burnished hues, glitter like steel and gold amidst the rays of the sun; not a few are strong and ferocious, and of all it may be said they supply abundant materials for interesting and instructive examination.

These creatures teem within the tropical latitudes. They tenant alike the land and the ocean; some prefer the river and the morass; while many are arboreal in their habits, flitting from spray to spray, and from leaf to leaf, in chase of insects. Reptiles swarm in sandy deserts, among dense

and tangled brushwood, in humid forests, and in pestilential swamps; they colonize the ruins of ancient towns and cities, palaces and temples, and often lurk unsuspected in the dwellings of men.

In the more temperate latitudes of the globe the number of these animals is greatly diminished; none are terrible from their size, and very few are to be dreaded for their poison. Passing still farther northwards, a few species remain which are harmless, while one or two besides, though furnished with poison-fangs, are capable only of destroying creatures of small size or a weak frame. The viper of Northern Europe is the representative in our latitude of the numerous deadly snakes which infest the countries of the tropics; and the harmless common ringed snake takes the place of the mighty python of Java and Bengal.

Localities where Reptiles are Frozen Out.

Advancing to the countries of the polar circles, we cannot find the snake, the lizard, the toad, or the frog. The low state of the temperature, the condition of the land and the water, and the deficiency of snails, insects, and other small animals, their usual food, combine to exclude reptiles from these desolate regions.

We may remark at the outset that reptiles, like birds, spring from an egg. The great marine tortoises, for example, come every year, at their appointed times, to deposit their eggs in the sand on the shores of the sea and banks of rivers, near strands of gentle declivity. There the females hollow out a sort of rude, but strong vaulted nest or oven, as it may be termed, wherein the eggs may have the benefit of the concentrated rays of the sun, so as to enjoy an equable heat, as in the instance of eggs under a sitting hen, but under circumstances which do not permit the body of the mother to impart the necessary warmth. The shell of these eggs is generally solid, and their form globular, or of a short cylindrical shape, equally rounded at the extremities. A female turtle will lay as many as a hundred at one time.

The reptiles differ from other animals in the mode of their respiration. Mammals breathe by expanding the cavity of the chest occupied by the lungs, into which, accordingly, the air enters, through the trachea, or windpipe, to fill up the vacuum occasioned by the dilation of the cavity. Now, this action supposes a certain degree of mobility in the walls of the chest, or, in other words, of the ribs and sternum, or breast bone, which encircle it, independently of the action of the diaphragm-the great muscle of respiration, which parts the chest from the abdominal cavity; but in tortoises the walls of the chest are immovable; they cannot be expanded; the bones are all locked into one solid mass, and there is no diaphragm

parting the cavity occupied by the heart and lungs from that containing the rest of the viscera. There must, therefore, be a peculiar mechanism by which the lungs become filled, and this is clearly discoverable.

If we watch a frog, for instance, we cannot readily discover that it breathes at all, for it never opens its mouth to receive fresh air, and there is no motion of the sides to indicate that it respires; and yet, on any sudden alarm, the animal may be observed blowing itself up, as if by some internal power, though its mouth continues all the while to be closed. The throat, however, may be observed in frequent motion, as if it were economizing its mouthful of air, and transferring it backwards and forwards. between its mouth and the lungs; while, if we look to the nostrils, a twirling motion may be noticed at each movement of the jaws; for it is, in fact, through the nostrils that the frog receives all the air it breathes.

A Creature Strangled by Opening its Mouth.

The jaws are never opened but for eating; and the sides of the mouth form a sort of bellows, of which the nostrils are the inlets, and by their alternate contraction and relaxation the air is swallowed, and forced into the trachea, so as to inflate the lungs. If the mouth of a frog be forcibly kept open, it can no longer breathe, because it is deprived of the power of swallowing the air required for that function; and if the nostrils be closed, in like manner it is suffocated.

The respiration of most of the reptile tribes is performed in a similar manner. The fact is, that the air is forced by the action of the tongue and mouth through the trachea into the lungs, by an act resembling that of swallowing; or rather, in the manner in which the ball or hollow butt of an air-gun is charged by repeated strokes of the piston.

The tortoises have lungs of great extent, passing backwards under the back-plate, and reaching to the posterior part of the body. Turtles, which are aquatic, derive great advantages from this structure, which enables them to give buoyancy to the body-encumbered as it is by a heavy shell-by introducing into it a large volume of air; so that the lungs, in fact, serve the purpose of a large swimming-bladder. That such was the purpose of this structure is evident from the volume of air received into the lungs being much greater than is required for the sole purpose of respiration.

All reptiles are cold-blooded, sluggish, and inert; subsisting on a scanty allowance of food. The heart of the frog may be regarded as consisting of a single ventricle and a single auricle. From the former there proceeds one great arterial trunk, which is properly the aorta. This soon divides into two trunks, which, after sending branches to the head and neck,

bend downwards, and unite to form a single trunk, which is the descending aorta. From this vessel proceed all the arteries, which are distributed to the trunk and to the limbs, and these arterial ramifications are continued into the great venous trunks.

The heart of the tortoise has two distinct auricles-the one receiving the blood from the pulmonary veins, the other, from those of the body generally; so that the mixture of aërated and vitiated blood takes place, not in the auricle, but the ventricle. When all the cavities are distended with blood, the two auricles being nearly of the same size as the ventricle, the whole has the appearance of the union of three hearts. On a similar plan the circulating system of the serpents is constructed.

The Famous Chameleon.

One character of the chameleon consists in the tongue being cylindrical, worm-like, capable of being greatly elongated, and terminating in a fleshy tubercle, lubricated with a viscid saliva. Another appears in the surface of the skin being covered with horny granules, instead of scales. A third is seen in the deep and compressed form of the body, which is surmounted by an acute dorsal ridge; a fourth, in the tail being round, tapering, and capable of grasping; and a fifth, in the parrot-like structure of the feet, which have each five toes, divided into two opposing setsthree being placed outwardly and two inwardly, connected together as far as the second joint, and armed with five sharp claws.

The head of these animals is very large; and from the shortness of the neck, it seems as if set upon the shoulders. The upper part generally presents an elevated central crust; and a ridged arch is over cach orbit to the muzzle. The internal organ of hearing is entirely concealed. The mouth is very wide; the teeth are sharp, small, and three-lobed. The whole of the ball of each eye, except the pupil, is covered with skin, and forms a single circular eyelid, with a central orifice. The furrow between the ball of the eye and the edge of the orbit is very deep; and the cyclid, closely attached to the ball, moves as it moves. As each eye has an independent power of motion, the axis of one eye may be seen directly upwards or backwards, while that of the other is in a contrary direction, giving to the creature a strange and most ludicrous appearance.

The chameleon was once said to live on air; but insects, slugs, and such like creatures form its food. For their seizure its tongue is especially adapted. With the exception of the fleshy tubercle forming its tip, it consists of a hollow tube, which, when withdrawn into the throat, is folded in upon itself, somewhat in the way in which a pocket telescope is shut up. When fully protruded, it reaches to a distance at least equal to