from the trunk, is not favourable for the execution of rapid, or continued movements; and the shortness of the jaws, and smallness of the mouth, indicate that the prey upon which these Reptiles feed, is weak and minute; having no teeth capable of tearing, or retaining in their gripe, victims of even trifling magnitude, they can only pursue, or attack such as can make no resistance, namely, insects, worms, and slugs. They are endowed neither with courage nor energy; and none are in the habit of taking to the water, or of seeking their prey there.

The species belonging to the genera in which the limbs are present, as usual, doubtless, climb and run with more celerity than those destitute either of one pair, or of all these organs; and appear to resemble our Lizards in habits, but without their restlessness and agility. The species without limbs, or with a rudimentary pair only, slowly crawl by winding flexures of the body; and as most have a lateral fold, which permits, on spreading, the application of the ribs to the ground, these also aid in progression. When the skin, as in the Ptychopleura, is covered with distinct horny scales, disposed in regular rings, the animals live on the surface of the ground, and in these the eyes are furnished with eyelids; but when the skin is covered only with square elevations, as in the Glyptoderma, there are no eyelids; and these animals generally live, like worms, in the soft earth, or in places where the light scarcely penetrates. It is known, that most of the species inhabit (as the Amphisbæna) the nests, or great mounds of sand, formed by the termite ants, which insects, destitute of wings, serve these creeping animals for food. The two extremities of the long body are of equal size, whence they have been, erroneously, termed double-headed snakes; and it is asserted, that they can crawl, like a worm, either with the head, or tail first, through the galleries which they bore in the humid or sandy earth; and hence, the name of Amphisbæna, which signifies a mover in both ways, head or tail first. In these, the eyes are minute, and covered by the skin,

and are only to be discovered by a black, or dusky spot, which the iris presents, as seen through the transparent membrane.

With regard to geographical distribution, Africa and America may be said to divide the Chalcidians between them, for, with the exception of one species, the sole example of its genus, (Trilobonotus, Dumeril and Bibron,) which inhabits New Guinea, they produce all the rest. It is in America, however, that we find the greatest number; for while Africa possesses fifteen species, belonging to five genera, America produces twenty-five, which have been regarded as examples of ten distinct genera.

It is, however, to be observed, that a few species have a general distribution, as, for example, the Scheltopusik, (Pseudopus Pallasii, Cuv.,) which inhabits not only the northern coasts of Africa, but also Dalmatia, the Morea, and the southern districts of Siberia, being at once African, European, and Asiatic. A species of Amphisbæna, (the Amphisbæna cinerea,) also inhabits northern Africa, together with Spain and Portugal; the other species being respectively American and African: and while out of four species of Chalcides, three are American, one (C. Schlegeli, Bibr.) is a native of the island of Java.

Without attempting an elaborate description of all the genera, which is not our present aim, we shall direct our readers to a few of the more remarkable; following them as they lead from the Lizards to the Snakes, irrespective of their subdivision into the sections alluded to.

GENUS ZONURUS.

This genus, subdivided into three sub-genera, Cordylus, Hemicordylus, and Pseudocordylus, is peculiar to Africa. In this group, the limbs are four, and robust; and there are one, two, or three rows of femoral pores; the feet are furnished each with five toes; the tail is short; and the head triangular and flattened. There are no teeth on the palate. The CORDYLE LIZARD

of Shaw, the ROUGH-SCALED CAPE LIZARD of Petiver, (Z. griseus, Bibr.,) is an example. It is a native of South Africa, where it is very common.

GENUS TRILOBONOTUS.

The genus Trilobonotus, of which one species only is known, is destitute of femoral pores; and may at once be distinguished by the scales of the back and tail, which, in the form of strong spines, present a formidable array. The plates covering the head, are soldered to the bones. Of this species, the NEW GUINEA TRILOBONOTE, (T. Nova Guinea,) we present an engraving. One specimen, in the museum of Leyden, is the only example in Europe. Of its habits nothing is known.

GENUS GERRHOSAURUS.

The genus Gerrhosaurus is distinguished by teeth on the palate; by the plates on the head being large, and very distinct from those on the neck; by the limbs being short, the hinder having femoral pores; by the scales of the body forming rings; and by a fold along each side. Five species are known, all natives of Africa and Madagascar.

We figure the Double-banded GERRHOSAURUS, (G. bifasciatus, Bibr., see engraving,) a native of Madagascar. Of its habits we know no details.

GENUS GERRHONOTUS.

Closely allied to the last genus, is the genus Gerrhonotus; the thighs, however, are destitute of pores. Of the eight species known, seven inhabit Mexico, one California. They produce their young alive; and in their habits closely resemble our Lizards.

GENUS CHALCIDES.

Passing from these more lizard-like groups, to the genus Chalcides, we arrive at a genus in which two pairs of limbs are, indeed, present, but both extremely short, and of which the posterior are sometimes represented by