tree to tree, where it searches among the leaves for the insects on which it subsists: but it cannot fly like the bird, or the bat, or the extinct Pterodactylus. Among the Mammalia, we find a certain degree of analogy to this Lizard in the flying squirrels, which have a membrane extending along the sides, between the anterior and posteterior extremities, so as to endow them with the power of taking long, skimming leaps, among their native branches.

The characters of the genus Draco, in addition to the membranous parachutes, are as follow. The body is covered with minute scales; the tongue is fleshy, and capable of very little power of protrusion. Beneath the throat hangs a pendulous fold of skin, forming a dewlap of considerable extent. The tail is long and slender. The teeth in each jaw consist of four little incisors in front, and on each side a canine tooth, and twelve little grinders, each crowned with three points.

One of the most common of the species is the DRACO DAUDINII of Bibron, (Draco volans, Gmelin.) It is a native of Java; and lives in the woods, on the branches of which it rests, concealed amidst the foliage. It is quick and alert in its actions.

We might here enter into the characters of several other genera, as Leiolepis, Grammatophora, Agama, Stellio, Uromastix, etc.; but as we aim only at a sketch, and as these genera are interesting rather to the naturalist than to the general reader, we shall omit an express account of them, referring the student to MM. Dumeril and Bibron's work on Reptiles, for full information.

VI. FAMILY, TRUE LIZARDS.

To the British naturalist, this family offers many points of interest. It is that to which every Lizard indigenous in our islands is referable; and of which, consequently, the habits and the manners are the best understood.

Our own species, therefore, will chiefly claim our notice, though not to the exclusion of some of the more remarkable of the genera peculiar to distant regions.

With respect to the general characters of this family, they may be summed up as follow :—

The body is rounded and elongated; and the tail, which mostly exceeds the body, is conical, terminating in a slender point, and is covered with scales, disposed in regular rings around it.

The limbs are well developed; the toes are four or five in number on each foot, and are armed with hooked claws.

The head is pyramidal, flattened above, and covered with plates; the tympanic membrane is distinct; there is usually a membrana nictitans, for the protection of the eye, besides the ordinary eyelids. The mouth is very wide, and its edges are covered with large labial plates.

The skin is scaly, the scales varying in form; but there is no dorsal ridge, though sometimes a ridge along the tail. The throat is not dilated into a dewlap; but a distinct row of large, broad scales, with one or more transverse folds, dividing between them and the general scaling of the under parts, forms a throat collar, which is very distinct. The abdomen is protected by scales, always much larger than those of the back, and either oblong or rounded. The thighs are mostly furnished with a line of pores.

The tongue is free, fleshy, slender, and bifid; it is capable often of great extension; and is frequently lodged in a basal sheath.

The teeth are variable in form and structure, but are inserted into the internal edge of a common furrow, running along the ridge of the maxillary bones. Sometimes there are teeth in the palate; sometimes the contrary.

And here it may be observed, that M. Dumeril divides the Lizards proper, into two sections, according to the characters which the teeth present.

The first section, which he terms Pleodonta, (πλeos, pleos, full, not hollow, and odovs, odovтos, odous, odontos, a tooth,) is distinguished by the teeth being completely solid, without any interior cavity; and by their being firmly fixed, by their edges and outer surface, to the bones of the jaws, in a groove, along the inner aspect of their ridge.

The second section, termed Colodonta, (koos, koilos, hollow,) is characterized by the teeth being hollowed by a sort of canal, and but slightly adherent to the bones of the jaws, against which they are placed in a groove within the ridge of the jaw; and to the bottom of which their base, or root, is not firmly attached.

The Pleodonta are all peculiar to America; the Cœlodonta to the old world. No true Lizard has yet been discovered, either in Australia, or the Polynesian islands.

Of all the Sauria, the animals of the present family are the most active and vivacious; their movements are distinguished by extreme promptness and rapidity, and they disappear from our sight, with the celerity of lightning. It is, however, only by sudden darts, and for short distances, that these movements are executed; and if the animals do not soon gain their hiding-place, or burrow, they become fatigued, and easily fall a prey to their enemies. Hence, they never undertake long excursions from their native spot, or from the retreat which they have selected.

If we notice a Lizard running over the ground, or diving amidst tangled herbage, we cannot but perceive that the movements of its body are serpentine. These animals, in fact, assist themselves in locomotion, not exclusively by the limbs, but, also, and that materially, by the body, and especially by the tail. The latter is liable to accidents, and is so brittle, as to break off easily, but it is soon renewed: the renewed part, however, is clearly distinguishable, by a difference of colouring, from the rest; and the vertebræ, instead of being hard and bony, are in a state of cartilage. We have said, that the head

of these Reptiles is covered with plates; these are of different sizes and figures, and have received different names, according to their situation. The annexed sketch will serve to explain their general character; but the reader must bear in mind, that they vary greatly in the various genera, and even species. a, the rostral plate; b, the nasal plates; c, the internasal plate; d, the fronto-nasal plates; e, the palpebral plates; f, the frontal plate; g, the parietal plates; h, the fronto-parietal plates; i, the interparietal plate; k, the occipital plates.

Besides these, may be enumerated the labial plates, which cover the edges of the mouth, or rather the margin of the upper and under jaws; the mental, (mentum, the chin,) or chin plate; and the sub-maxillary plates, which cover the under surface of the lower jaw, from the chin to the throat.

I. PLEODONTA.

We have said that the Pleodonta are exclusively American.

GENUS ADA.

To this section belongs a group, of which the genus Ada, of Mr. Gray, (divided by M. Bibron into the genera Crocodilurus and Thorictes,) is an example. The species, in size and aquatic habits, and in the compressed form of the tail, approach the Crocodiles. The tail, in fact, is not only compressed, and oar-like, but is surmounted by a double serrated, scaly ridge, the one distinct from the other, extending down its whole length. These Reptiles, although the toes are not palmated, like those of the Crocodile, pass the greater portion of their life in the water. It is in the large rivers,

With a tail like that of a Crocodile.

lakes, or wide morasses of South America, that these Lizards are to be seen; but we know little of their habits.

The COMMON ADA, of Mr. Gray, (Thorictes dracana, Bibron; La grande dragonne, Cuvier,) attains to the length of from four to six feet. It is a native of Guiana; and, if the large Lizard which M. Humboldt and Bonpland often saw, in the lake of Valencia, be the same, it also inhabits Mexico.

In Guiana, it frequents the morasses and lakes; and is said to be very frequently seen on the land, as often, indeed, as in the water: it is not easy to capture alive, because, when pursued, it takes refuge in its burrows, or holes, which are deep. M. de Laborde kept one of these animals for some time; it passed whole hours in the water, and when alarmed, fled to it, and plunged in, in order to conceal itself. It was fond of lying on the water's edge, basking in the rays of the sun. It bit very severely, inflicting painful wounds; and would frequently shoot out its quivering tongue, like a serpent. Its flesh is accounted excellent by the natives, who compare it to that of a fowl; its eggs are, also, in great request.

Passing from the crocodile-like Lizards, we come to an allied group, in which the tail is either conical, or slightly flattened both above and below, and at the sides; the angles, however, being rounded. To this group belongs the genus Teguixin, Gray, (Salvator, Bibron ;) and to which, when noticing the Varans, we have already alluded.

GENUS TEGUIXIN.

In the genus Teguixin, the tongue is bifid, very long, and extensible; there are no teeth on the palate; the nostrils open on the sides of the extremity of the muzzle; the tympanic membrane covers the orifice of the ear; the skin of the throat forms two or three transverse folds; the back is covered with little angular scales,