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“ He that has humanity, forewarn'd, will tread aside, and let the reptile live."--COWPER.

moult, or

change their feathers,

1000. Why do birds periodically?

The moulting of birds is a process analogous to the nutrition, expenditure, and decay, which occurs in all animal bodies. When an atom, or it may be an organ, has fulfilled its functions, it dies ; and when completely dead, it separates and falls, because a dead substance cannot co-exist with a living.

Moulting is nothing else but this natural death of part of the bird, in consequence of the development of other interior parts, which are being matured to carry on the functions of the parts undergoing decay.

some

1001. We find the germs of leaves, flowers, and fruits, in vegetables, and tho hairs, feathers, scales, horns, epidermis, &c., in animals increasing and developing themselves in spring, to flourish in succession, at least for the duration of the summer. But at the approach of the autumnal equinox, plants and animals, being more or loss exhausted by the vast expenditure of their vital forces in the great work of reproduction, and also by the increased energy with which those vital forces acted in proportion to the surface, their external functions begin to be enfeebled, and by so much the more as the heat of the sun diminishes. Then these external parts, these vernal productions, cease to receive aliment through the body: they have, besides, arrived at the full term of their augmentation, and can admit of no further nutriment. They dry up, wither, are detached, and fall. Thus is produced, sooner or later, the fall of flowers, leaves, and fruits, and the change of hairs, feathers, horns, epidermis, scales, &c.

CLASSIFICATION OF THE VARIOUS REPTILES.

CLASS III.-REPTILIA.

ORDER I.-CHELONIA.

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1002. Why is the first order of reptiles called chelonia ?

From a Greek word meaning a tortoise ; the order including the various species of tortoise and turtle. They have horny cases, are destitute of teeth, have thick fleshy tongues, well developed eyes, and their limbs differ from an elephantine club foot, to feet divided and webbed.

“ A tortoise, introduced here (Lambeth Palace) in 1633, lived till the year 1753, and possibly might have continued much longer, had it not been for the carelessness of the gardener.”

PENNANT.

1003. Why are reptiles so called ?

The term is derived from a Latin word repo, I creep; since the imperfection of the legs and feet in some cases, and the total absence of these members in others, necessarily entail a creeping movement to enable the animal to move along the ground.

1004. Why are turtles and tortoises covered with hard external shells ?

Because they are destitute of bony skeletons within, and the horny covering is made to answer all the purposes of the usual osseous structure.

But, besides this, they are defenceless animals, except so far as the shell affords a retreat to the head, legs, and tail, which are withdrawn within the shell upon the occurrence of any danger.

1005. It may appear at first sight that there is a great affinity between the armour, or rather box, in which the tortoise is enclosed, and the coat of mail with which many quadrupeds are covered, as, for instance, the armadillo (416). But there is this important difference: the coat of mail in the latter quadruped is a simple horny addition to the skin itself, resting upon, and supported by, processes of the skeleton; whereas the osseous shell of the tortoise is part and parcel of the skeleton itself, which is so modified as to protect the internal organs, enclosing them as in a casket, which is covered either with horny plates variously arranged, or with a tough leathery skin.*

1006. Why do the checks of tortoises and turtles appear to be frequently distended ?

Because they swallow air instead of breaking it by the ordinary process. The jaws being firmly closed, the cavity of the mouth is enlarged by the drawing down of the root of the tongue; and into the vacuum thus formed the air rushes through the nostrils. The free part of the tongue is then applied to the posterior openings of the nostrils, so as to stop them; the gullet is also closed, the root

the tongue is elevated, the broad muscles of the throat contract,

• Knight's “Museum of Animated Nature."

A lizard's body lean and long,

A fish's head, a serpent's tongue.”-MERRICK.

and the air is forced the windpipe into the lungs, which become filled by a repetition of the process.

1007. Why have tortoises and turtles no teeth ?

Because, for cropping the tender vegetation upon which they live, teeth are less adapted than the serrated horny coverings with which they are provided, and by which they are enabled to crop and mince the vegetable aliment upon which they subsist.

ORDER II.-SAURIA.

1008. Why is the second order of reptiles denominated sauria ?

From a Greek word meaning a lizard. The mouths of these animals are always armed with teeth, and the toes are generally furnished with claws. They have all a tail more or less long, and generally very thick at the base.

1009. Why does the crocodile, which devours birds, beasts, and even human beings, allow one species of bird, the ziczac, to be on familiar terms with him ? It is said that when the crocodile comes on shore, he opens his

jaws, and this bird enters and swallows the leeches which are found about the animal's jaws and teeth, and which have collected there owing to the creature being for so long a time in the water; the relief afforded by having the leeches withdrawn, induces the croco

dile not only to tolerate the advances of the bird, but to encourage them.

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“ An alligator stuffed, and other skins of ill-shap'd fishes."

SHAKSPERE.

1010. This is a disputed point in natural history, and is doubted simply on account of its apparent improbability, rather than from any evidence which has been adduced to the contrary. The following anecdote, however, related by Mr. Curzon, goes far to confirm this seemingly incredible account :—“I had always,” says Mr. Curzon, “a strong predilection for crocodile shooting, and had destroyed several of these dragons of the water. On one occasion, I saw a long way off a large one, twelve or fifteen feet long, lying asleep under a perpendicular bank, about ten feet high on the margin of the river. I stopped the boat at some distance; and, noting the place as well as I could, I took a circuit inland, and came down cautiously to the top of the bank, whence, with a heavy rifle, I made sure of my game. I had already cut off his head in my imagination, and was considering whether it should be stuffed with its mouth open or shut. I peeped over the bank : there he was within ten feet of the sight of the rifle. I was on the point of firing at his eye, when I observed that he was attended by a bird called the zic-zac. It is of the plover species, of a greyish colour, and about the size of a small pigeon.” The remainder of the narrative corroborates the fact.

1011. Why do both jaws of the crocodile move ?

Because its habits of life render it necessary to be able to seize its prey with great rapiditythe prey often lying on the surface of the water. The power of moving both jaws facilitates this kind of seizure, by bringing the level of the water surface instantly and equally within the action of the upper and lower jaws.

1012. Why is the alligator so called ?

Either from the Spanish and Portuguese lagarto, meaning a lizard, or from the Latin lacertus, the arm, in reference to the arm-like appearance of the legs.

1013. Why are the monitor lizards so called ?

It is said that when the larger reptiles approach them they utter a cry of alarm, which gives warning to other creatures of the dangerous approach of the crocodile and the alligator.

1014. Why has the chameleon the power of changing its colour ?

This faculty has been attributed to the protective instinct of the animal, by which it seeks to render itself less observable by enemies, by assuming the colour of the bed upon which it lies,

“ Wak'd by his warming ray, the reptile young

Come wing'd abroad ; by the light air upborne,
Lighter, and full of soul.”-Thomsox.

1015. The means by which this change of colour is accomplished is a matter of doubt. Some naturalists attribute it to the distension of the chameleon's body occasioning differcnces in the cuticle, affecting its reflective properties ; others, that the animal has the power of throwing into its skin a different pigment, or colouring matter, from the blood; others, to nervous or galvanic action. "The chameleon, though long an object of interest and study, still presents many remarkable characteristics demanding explanation.

It appears, from the observations of Dr. Weissenborn, who had a chameleon for :some time in his possession, that the nervous currents in one half of the animal may go on independently of those in the other, and that the animal has two lateral centres of perception, sensation, and motion, besides the common one in which must reside the faculty of concentration. “Notwithstanding the strictly symmetrical structure of the chameleon, as to its two halves, the eyes move independently of each other, and convey different impressions to their centres of perception. The consequence is, that when the animal is agitated, its movements appear like those of two animals glued together. Each half wishes to move its own way, and there is no concordance of action. The chameleon, therefore, is not able to swim like other animals; it is so frightened if put into water, the faculty of concentration is lost, and it tumbles about as if in a state of intoxication. On the other hand, when the creature is undisturbed, the eye which receives the strongest impression propagates it to the common centre, and prevails upon the other eye to follow that impression, and direct itself to the same object. The chameleon, moreover, may be asleep on one side, and awake on the other. When cautiously approaching my specimen at night with a candle, so as not to awaken the whole animal by the shaking of the room, the eye turned towards the flame would open, and begin to move, and the corresponding side to change colour, whereas the other side would remain for several seconds longer in its torpid and changeable state, with its eye shut.”

1016. Why has the agama the power of inflating its body with air?

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