when a few slender bones are found, the rudimentary representatives of the pelvis, and bones of the thighs and legs, as we see them in higher animals. The skeleton of a Snake is very elegant, and at once conveys to our minds an idea of flexibility; and this is borne out by an examination of its component parts.

SKELETON OF A SNAKE.

On turning to the vertebral column, we find it to consist of a series of bones united to each other, by ball and socket articulations; the head of each separate vertebra being received into a deep, cup-like cavity of the one succeeding it. The whole of the spine is, in fact, a chain of these joints, firmly locked together, and each moveable to such an extent, as is compatible with the safety of the spinal chord. On referring to the sketch, this description will be better understood.

A, is one of the vertebræ, removed to show the arti

culating ball, b, which is fitted into the cup, c, of the next vertebræ, E.

The Snake is capable of twining in the most extraordinary manner; but, after all, its pliability consists less in the mobility of each joint separately, great as this may be, than in the number of joints into which the column is divided. From each of these distinct bones, (those of the tail excepted,) forming the vertebral column, and which are so numerous, (amounting, in some species, to more than three hundred,) two ribs arise, one on each side, (see skeleton of Serpent.) These ribs form a great portion of a circle, so as to embrace nearly the whole circumference of the body, and are the efficient agents of locomotion. They play each on a convex protuberance of the respective vertebræ, and are acted upon by powerful muscles, which move them backwards and forwards. Instead of being attached by their extremity to a breast-bone, as in Mammalia and lizards, each pair of ribs is connected with one of the scuta of the under surface, by means of a slender cartilage. It is on the points of these ribs, which may be likened to the limbs of a millipede, that the weight of the Snake rests; and they work in progressive order, like the legs of that creature. While the muscles, after each progressive stroke, keep the anterior ribs firm, the body, by the action of the rest in rotation, is brought up in a series of undulatory move

ments, the anterior ribs at the proper instant taking up their work. The ribs move, of course, in pairs, and each pair as it is advanced, carries forward with it the scale to which their extremities are fixed; so that each of these scales may be regarded as a broad firm termination, or foot, common to a pair of ribs; and their projecting edges, laying hold of the ground, become a fixed point for the advance of the body. If a Snake be allowed to crawl over the hand, the progressive movement of the ribs, and the advance and application of the edge of each scale may be distinctly felt. The same may be seen when a Snake crawls over the back of a book, or any raised edge requiring the firm application of only one or two scales at the same instant.

The ordinary motion, then, of the Snake, is by a succession of short steps, taken by its numerous ribs, as we see when looking at a millipede; the foot of these ribs (we might say limbs) being a broad scale, common to each pair. A more rapid progress, however, is effected by the body being thrown into great curvatures, the fore part being fixed, and the rest being brought up by the action of the muscles and ribs; the hind part, or tail, being then fixed, and the fore part projected forwards, and so on alternately. In this manner, the Snake can glide along with great velocity, the body assuming a series of rapid undulations from side to side. These animals, however, can also proceed in a series of bounds. The body is raised in the form of an arch, with the head and neck on the one part, and the tail on the other, touching the ground; the tail is brought up to the head, and fixed, the head is raised, then darted forwards, and again fixed, the back arched, and the tail brought up as before.

Many Serpents can spring vigorously and suddenly, and thus dart upon their enemy. In order to do this, they generally first coil themselves up, in a spiral manner, by the contraction of the muscles of one side; then by the sudden relaxation of these muscles, and the violent

and instantaneous action of the muscles of the other side, which uncoils them, they are propelled with great quickness, and to a considerable distance. When a spiral spring, the coils of which are distant, is pressed upon the table till they close, and suddenly released, we see a similar projectile impulse given.

We shall now pass to a consideration of the skull of Serpents, as far, at least, as regards the general mechanism of its structure.

The Snake, as is well known, is capable of swallowing its undivided food, many times larger in bulk than the circumference of its own body; nay, the disproportion, in this respect, is almost incredible. That the skin, the gullet, and the stomach, are capable of enormous dilatation, is a wise provision in its favour: but with every allowance for the dilating powers of the skin and viscera, a difficulty still remains; namely, the passage of the food through the jaws.

Here we see one of the beautiful instances of harmony, which are ever apparent in the works of the Almighty. The bones forming the jaws and face (so to call it) of the Snake, unlike what is seen in Mammalia, where they are firmly locked together, and where the lower jaw moves on closely bound hinges, are all loose and unconnected, except by skin and ligaments. The upper jaw is in two pieces, with a separate intermaxillary bone between the points of each; and the bones of the face, continuing in their state of elemental subdivision, are all disunited. The lower jaw is also composed of two distinct lateral branches, each branch being, in fact, itself made up of two portions, united by a loose kind of suture. Instead of being secured by firm points to the skull, the lower jaw is attached on each side, by a lax articulation, to a moveable bone, called the tympanic portion of the temporal bone. The articulation admits of a natural kind of dislocation, so that it gives way in the act of swallowing, and recovers itself when the prey is fairly engulphed. The annexed figure represents the

upper view of the skull of the Python of Java, a Serpent

of enormous mag

nitude; and shows

the manner in which the bones are all subdivided. The skull is attached to the first vertebra by a single condyle only. Such is the general plan of construction in the Serpent's skull: there is, it is true, considerable modification of details, in different

species,

but the great outline is the same. Serpents may be characterized as poisonous, or venomous, that is, producing death by

their bite; or as innoxious, that is, producing by their bite no mischief beyond the wound itself.

Among the innoxious tribe, we may place the Boa, the Python, the common Snake of England, and many more. These all possess a double row, on each side, above, of sharp-pointed teeth, regularly inclined backwards, so that the hand may be passed down over them with impunity, but not drawn back; for then, they pierce the skin immediately. Hence, while they offer no impediment to the passage of food, they securely detain the struggling victim. Of this double row of teeth, on each side, above, one runs along the jaw bone, the other along the bone of the palate.

The cut on next page represents the under surface of