and furnished with nails. It presents us with only two species; of these, one, the VERMILION TORTOISE, (Homopus areolatus,) is a native of eastern Africa and Madagascar.

Its colour after death, is generally a pale green, the centre of each plate being of a chesnut brown; while the limbs and head are yellowish. When alive, however, the top of the head is of a fine red, the jaws and limbs are greenish, and the neck black, with a tinge of green. The carapace varies from yellow to yellowish green, or pale green sometimes intermingled with shades of purple; but the margin and the centre of each plate are chesnut coloured.

This species is of one the smallest known of land Tortoises, seldom exceeding five or six inches in total length. The other species (H. signatus, Bibr.) is also a native of Africa; but its shell only has been hitherto described. We have been able to ascertain nothing respecting their habits.

GENUS PYXIS.

This genus is distinguished by the anterior part of the plastron being moveable, and capable of being closed on the upper shell, so as to shut in the animal's head and fore-limbs.

One species only is known, namely,

The ARACHNOID TORTOISE, (P. arachnoides, Bell.) The first description of this curious Tortoise is due to Mr. Bell, whose account was published in the 15th vol. of the Linnean Transactions It is a native of India, and the islands of the Indian Archipelago; but we are entirely without information as to its habits and manners.

It is natural to ask, why this creature should have its shell so constructed, as to be able to shut itself up within it. Doubtless, it has some peculiar enemies, against which it needs this curious mode of self-protection. What these enemies may be, we do not know; but this we do know, that extraordinary contrivances for effecting the preservation of any animal, imply the liability of

that animal to attacks from foes, which render such contrivances necessary; contrivances which bespeak the care of the great Creator.

The general colour of the head, neck, and tail, is brown; the limbs are yellowish, with a black stripe. The ground colour of the carapace is reddish yellow; each plate has eight or ten triangular black marks, disposed in a radiating manner: the plastron is of the same colour as the carapace, with black marks on each side. This species is of small size, being about six inches in total length. The annexed sketch represents this prettily

marked Tortoise in two aspects: Fig. 1, shows the under surface; the joint of the plastron is clearly visible: fig. the upper.

2,

GENUS CINIXYS.

in page 19, contains but three species, as far as known at present. Two of the species are natives of Guiana; but the country of the third is not ascertained.

No information respecting the habits of the animals of this species has been received. The species in question are HOME'S TORTOISE, (C. Homeana, Bell;) the INDENTED TORTOISE, (C. erosa, Gray;) and BELL'S TORTOISE, (C. Bellii, Gray.)

We shall now leave the land, or terrestrial Tortoises, having said enough to give a clear idea of their general character. The reader must remember, that we aim only at an outline, and not at a description and comparison of every species; and will, therefore, not be surprised at our passing rapidly from one group to another.

II. MARSH TORTOISES, OR EMYDES.

THE family to which we now proceed is much more extensive than that of the land Tortoises. All the species inhabit marshy places, ponds, lakes, and small rivers. The conformation of their feet, to which we have alluded, enables them both to swim with facility, and to walk on the ground; they can leave the water at will, and crawl about the banks of the stream, or traverse the muddy margin of the lake, to which they always retreat for safety. We have stated, that in the land Tortoises the osseous box in which they are inclosed is strong and thick, and completely solidified; the upper portion, or carapace, being remarkable, at least in most instances, for its convexity. In these marsh Tortoises, however, not only is this box less thick and strong than in the land Tortoises, but it remains for a considerable period before becoming solidified. Long after the animals are hatched, the spaces between the ribs, and the intervals which separate the parts of which the plastron is

composed, are in a cartilaginous state, and yield to the pressure of the finger. In some species, this slowness of ossification is more remarkable than in others; but when the ossification is complete, the whole forms but a comparatively feeble shield; and the carapace, moreover, is greatly, depressed, except in two or three instances. Generally, the horny plates covering the carapace are thin and smooth, exhibiting either no areolæ, or marked centres, and linear elevations, or but slight indications of them. In some instances, the scales are arranged like slates on the roof of a house; the posterior margin of one, overlaying the anterior margin of that next following.

The general figure of the osseous box of the marsh Tortoise is oval; mostly, however, the carapace is broader behind than before, but sometimes there is no difference; and in these cases, the sides of the carapace between the fore and hind limbs are straight.

Almost all the marsh Tortoises are capable of withdrawing and concealing their limbs and head within the carapace and plastron; and in the genus Cistudo, by aid of the two moveable portions of the latter, the animals can completely shut themselves up. But in the genus Emysaurus, neither the carapace nor plastron is sufficiently extensive to allow of the concealment of those parts; and in another genus, Platysternon, the plastron from its breadth suffices to conceal the limbs when folded; but the head remains constantly exposed. The limbs are never covered with coarse tubercular scales; the scales, on the contrary, are always flat, thin, small, and disposed like tiles, that is, imbricated.

The tail generally extends beyond the margin of the carapace as far as the feet when they are stretched back; sometimes, however, it is very short.

The neck is mostly of considerable length, not however from the number of the vertebræ, which is usually only eight, but from their elongated form; when retracted, it is either folded back upon itself, as in one

group, (the Cryptodera,) or turned to one side, as in another group, (the Pleurodera).

In modes of life and general habits, the marsh Tortoises are very different from their terrestrial relatives. Far from being slow and laboured in their movements, they are prompt, and comparatively quick, and they swim. with considerable address. Their food, instead of consisting of vegetable substances, is derived from another source. They are carnivorous, and prey upon frogs, insects, worms, and small fishes, which they pursue with avidity. Like the land Tortoises, the females deposit their eggs in shallow excavations, which they make in the earth, on the banks of the waters which they ordinarily inhabit; so that as soon as the young are hatched, they may have a place of refuge from danger; for, at this early age, they have many enemies to avoid, such as snakes, birds of prey, and various quadrupeds.

The number of Tortoises belonging to this family, as far as known at present, amounts to seventy-four. Of these, according to M. Bibron, three are European, eighteen Asiatic, six African, twenty-three South American, twenty-two North American, and two Australian. We have previously stated, that the marsh Tortoises are divided into two sub-families or tribes, namely, Cryptodera and Pleurodera.

The Cryptodera are distinguished from the Pleurodera, not only by the power which they possess of withdrawing their cylindrical neck, sheathed in loose skin, immediately under the centre of the fore part of the carapace, but also by the shape of the head. The head at the back part, is as deep as it is broad, and it diminishes in breadth from the eye to the muzzle; so that at its fore part it assumes the form of a blunt triangle. The eyes are placed on the sides of the head, and the orbits are large. The jaws are much stronger than in the Pleurodera; they have sometimes only a simple cutting edge;