them was seen in latitude 30° north, sleeping on the surface of the water, apparently about midway between the Azores and the Bahama islands, and these were the nearest possible land. This circumstance was the more remarkable as it happened in the month of April, just at their breeding time*.

Like the last species, they lay their eggs in the sand. Their flesh is coarse and rank; but their bodies afford a considerable quantity of oil, which may be used for various purposes. The plates of the shell are not sufficiently thick to be of great use.

The substance that we call Tortoise-shell is the production of the Imbricated Turtlet, a species, considerably allied to the present, that is found in the Asiatic and American seas, and sometimes in the Mediterranean. The plates of this species are far more strong, thick and clear, than in any other, and these constitute the sole value of the animal. They are semi-transparent, beautifully variegated with different colours, and, when properly prepared and polished, are used for a variety of ornamental purposes. They are first softened by steeping in boiling water, after which they may be moulded into almost any form.

* Catesby, ii. 40.

† Testudo imbricata of Linnæus.

Shaw's Gen. Zool. iii. 89.

THE FROG TRIBE.

THE animals that compose this tribe feed on insects and worms, residing principally on the ground, or partly in water, in dark and unfrequented places, from whence they crawl forth only in the night. Many of them have an aspect very disgusting and unpleasant. Some, however, are furnished with slender limbs, and have their toes terminated by flat circularly expanded tips, which enable them to adhere at pleasure to the surfaces of even the smoothest bodies: these reside generally in the trees, where they adhere to the lower sides of the leaves or branches. -None of them drink, but all the species absorb moisture through the skin.

They are all oviparous, and the eggs are perfectly gelatinous. From the egg proceeds a Tadpole without feet, but furnished with a tail to aid its motions in the water: this drops off as the legs become protruded. In this state they have also a sort of gills or subsidiary lungs; and several of them a small tube on the lower lip, by means of which they can fix themselves to bodies, to eat, or perform other functions. They all arrive at maturity about their fourth year, and very few outlive the age of ten or twelve.

The full-grown animals have four feet, and their body is not covered with either plates or scales, but is entirely naked. They are destitute of tails, and their hind-legs are longer than the others.

The number of species hitherto described is about fifty. These are divided into three sections; namely, Frogs, which have smooth bodies, longish legs, and discharge their eggs in a mass.

Hyle, that have their hind-legs very long, and the toes unconnected; and

Toads, which have their bodies puffed up and covered with warts. These have also short legs, and do not leap; and discharge their eggs in a very long necklace-like string.

THE COMMON FROG*.

The Common Frog is found in great quantities in moist situations throughout Europe. Its colour is olive brown variegated above with irregular blackish spots. Beneath each eye is a patch or mark that reaches to the setting-on of the fore-legs.

Its appearance is lively, and its form on the whole by no means inelegant. The limbs are well calculated for aiding the peculiar motions of the animal, and its webbed hind-feet assist its progress in the water; to which it occasionally retires during the heats of summer, and again in the frosts of winter. During the latter period, and till the return of warmer weather, it lies in a state of torpidity, either deeply plunged in the soft mud at the bottom of stagnant waters, or in the hollows beneath their banks.

Rana temporaria. Linn.-Shaw's Gen. Zool..vol. 3. tab. 39.

Its spawn, which is cast generally in the month of March, consists of a clustered mass of gelatinous transparent and spherical eggs, in the middle of each of which is contained the embryo or tadpole, in the forin of a black globule. The spawn lies a month or five weeks, according to the heat of the weather, before the larvæ or tadpoles are hatched.

The tadpole, as in several other species, is furnished with a kind of small tubular sucker beneath the lower jaw, by means of which it hangs at pleasure to the under surface of aquatic plants. The interior organs, when closely examined, are found to differ in many respects from those of the future Frog. The intestines, in particular, are coiled into a flat spiral form, somewhat resembling a cable in miniature. When the animal is about six weeks old the hind-legs appear, and in about a fortnight these are succeeded by the fore-legs in this state it seems to have alliance both to the Frog and Lizard. Not long afterwards the form is completed, and it, for the first time, ventures upon land. Frogs are at this period often seen wandering about the brinks of the water, in such multitudes as to astonish mankind, and induce a belief among the vulgar of their having descended in showers from the clouds.

They now surrender their vegetable food for the smaller species of snails, worms, and insects; and the structure of their tongue is admirably adapted to seizing and securing this prey: the root,is attached to the fore-part of the mouth, so that when unemployed it lies with the tip towards the throat. The animal is by this singular contrivance enabled to bend it to a considerable distance out of its mouth. When

it is about to seize on any object, it darts it out with great agility, and the prey is secured on its broad and jagged glutinous extremity. This it swallows with so' instantaneous a motion that the eye can scarcely follow it*.

Nothing canappear more awkward and ludicrous than a frog engaged with a large worm or a small snake; for nature seems to have put a restraint upon the voracity of these animals, by forming them very inaptly for seizing and holding their larger prey. Dr. Townson had a large Frog that one day swallowed in his presence a Blind-worm† near a span long, which in its struggles frequently got half its body out again : when completely swallowed, its contortions were very visible in the flaccid sides of its victor‡.

With respect to the popular superstition that Frogs frequently descend from the clouds, Mr. Ray informs us, that as he was riding one afternoon in Berkshire, he was much surprised at seeing an immense multitude of Frogs crossing the road. On further examination he found two or three acres of ground nearly covered with them; they were all proceeding in the same direction, towards some woods and ditches that were before them. He however traced them back to the side of a very large pond, which in spawningtime he was informed always abounded so much with Frogs, that their croaking was frequently heard to a great distance; and he therefore naturally concluded that instead of being precipitated from the clouds, they had been bred there, and had been invited by a

* Shaw's Gen. Zool. iii. 97. † Anguis fragilis of Linnæus,

Townson's Tracts.