"Lo! the green serpent, from his dark abode, ORDER III.-OPHIDIA. 1017. Why is the third order of reptiles termed ophidia? 1018. Why are serpents unprovided with feet? One reason, at least, may be found for this deprivation in the fact that, as they are adapted for fulfilling certain ends within particular geographical limits, they are confined to those limits by the absence of locomotive organs'? If creatures like the boa and the rattle-snake could spread themselves from the hot to the temperate latitudes, and diffuse themselves generally through these, they would prove serious pests, and formidable enemies to a great number of useful races. 1019. How are serpents enabled to move along the ground without feet or legs? Locomotion is effected by the contractile force of the muscles, alternately drawing up and extending the body, combined with the adhesion of the tegumentary covering with the ground. The animal attaching to the ground a point near its head contracts its body, or bends it into an arch, bringing forward the "Snakes breathe their amorous sighs in hisses. hinder part, some point of which is then attached to the ground, liberating at the same time the fore part. The posterior point of attachment then becoming a fixed point, the animal throws forward its length by the action of its extensor muscles, after which it again attaches a point in the foremost part of its body to the ground, and repeats the same process. 1020. Why do serpents let themselves fall from trees without sustaining injury? Because their peculiar form, and the elasticity of their parts, prevent concussion from such falls. On reaching the ground, the shock they sustain, instead of proving hurtful, impels them forward, and serves as a stimulus to their subsequent movements. 1021. How does the snake throw its whole body from the ground in a kind of leap? This is performed by placing the body upon the ground in form of a twisted spiral, the folds of the anterior part forming the centre of the figure; then suddenly extending itself in the manner of a spring, it throws itself to a distance. 1022. This movement may sometimes be seen in very hot weather by the banks of the stream, where snakes often lie basking with their bodies coiled in the manner just described, the neck and head being directed from the centre to the circumference above the folds. This position seems to be preferred to any other by the snake while reposing; and it is one from which the animal is enabled to perform the most rapid movement upon a sudden surprise; for, in a wood, from this position they will leap by an instantaneous effort into the brushwood, and thus elule our most energetic efforts to secure them, or even to get sight of them; but by the side of a stream this movement may be better seen, for on a sudden approach they will leap from the bank into the midst of the stream, swim to the opposite side, ascend the bank, and secrete themselves. 1023. Why is the rattlesnake provided with a rattle at the extremity of its tail? The use of this curious apparatus is unknown, though so obvious a contrivance cannot be without its specific uses. "Where at each step the stranger fears to wake The rattling terrors of the vengeful snake."-GOLDSMITH. It has been alleged that it is a signal of warning to keep away animals that might hear it, from the deadly venom of the snake. But it is altogether opposed to the economy of nature to endow an animal with means to scare away the prey upon which it must subsist. It is not unlikely that, as the snake does not climb trees, nor move about with the graceful evolutions of other tribes, but glides along the ground in low and secret places, the rattle is used as a call to members of its own species. 1024. Why have serpents the power of fascination? Being deficient in organs of locomotion, the power of fascination has probably been bestowed upon them as a compensatory endowment. Otherwise, what chance would there be of a snake bringing down a bird, or pursuing successfully a swift rabbit? 1025. Why are the Indian snake-catchers enabled to charm snakes? It seems to be well-established by observation that certain kinds of serpents are exceedingly impressible by musical sounds. A similar fact has been noted with respect to seals, rats, mice, and other animals. But serpents appear to be impressible in a higher degree, and the Indians, who study their habits, learn the exact notes by which the serpents are most affected, and acquire the power of what has been termed "charming them." ORDER IV.-AMPHIBIA. 1026. Why is the fourth order of reptiles called amphibia? From two Greek words, meaning both and life. Amphibials are animals formed to live on land, and to be also capable of living for a long time under water. Their hearts have but one ventricle; their blood is red and cold; and they have such a command of the lungs, as for a considerable time to suspend respiration. These peculiarities, which characterise the amphibia in particular, apply also generally to all the order of reptiles. M "Onely these marishes and myrie bogs, In which the fearefull ewftes do build their bowres, Yield me an hostry 'mongst the croaking frogs."-SPENSER. 1027. Why when the frog is breathing does it keep its mouth firmly shut, and also continually raising and lowering the skin between the bones of the under jaw? Because, owing to its peculiar structure, it cannot breathe with the mouth open; and if it were forcibly kept open, the animal would die of suffocation. 1028. The explanation of this apparent anomaly is as follows:-The frog receives the air which is to be conveyed to the lungs through the nostrils, but there is no vacuum or cavity formed by the expansion of the thorax, so that the mere pressure of the atmosphere following the expansion, does not, in this instance, inflate the lungs. An effort is required after the air is taken into the body, and that is performed chiefly by the tongue. The depression of the skin of the lower jaw lasts much longer than the elevation, because there is a double operation to be performed-the expulsion of the air already in the lungs, and the re-admission of fresh air into the body. When that skin first descends, there is a contractile action of the abdomen, by which the air in the lungs is driven out; and when that is all expired, the abdomen returns to its natural state; but being without bones it cannot form a vacuum, and thus the lungs could not be inflated but by some other action capable of overcoming the resistance of their cells. 1029. How are the showers of frogs, which are often reported as taking place, accounted for? The explanation of this apparent phenomenon is as follows: It is generally about the month of August, and often after a season of drought, that these hordes of frogs make their appearance; the animals have been hatched, and quitted their tadpole state, and native pond. Finding the fields hot and parched, they seek the coolest and dampest places, and conceal themselves under "I had rather be a toad, and live upon the vapour of a dungeon, than keep a corner in the thing I love for others, uses."-SHAKSPERE. clods and stones, where, on account of their dusky colour, they escape notice. When the rain descends, they come forth in hundreds from their hiding places, and hence are supposed to have fallen to earth in a shower. 1030. How is the bull-frog enabled to make the bellowing noise from which it takes its name? This sound is produced by certain portions of the larynx of the animal being convex externally and concave internally, so that when the entrance to the larynx is closed, they form a dome over the windpipe, which, from its vibratory properties, has been compared to a kettle-drum. 1130. How is the croaking of the frog produced? This peculiar sound, which is supposed to be expressive of pleasure, is produced by means of the air which it forces into the globular vocal sacs, which are situated near the corners of the mouth, and causes to vibrate in them. The female being without these organs, produces only a slight noise. 1032. Why are frogs frequently found dead in dusty roads? Because their skin co-operates with their feeble lungs in the aëration of the blood. This internal respiration can only take place when the skin is bedewed with moisture. For this purpose the frog is endowed with certain glands that secrete a fluid to moisten the skin. In dusty roads this fluid becomes clogged with dust, and the respiration of the skin being stopped, the animal dies. 1033. Why are toads useful in greenhouses and other horti cultural buildings? Because they destroy ants; and devour earwigs, caterpillars, small beetles, slugs, and all insects which chance to fall in their way. |