It is from the sound, or air-bladder of this species, that the wellknown substance called isinglass is prepared: this is done by cleansing, splitting, and drying that part, either in the air, or occasionally by a fire, and either twisting or flattening it, according to the particular sorts by which it is distinguished in commerce. An ample account of the preparation of this useful article, may be found in the sixty-third volume of the Philosophical Transactions: the skin, tail, stomach, and intestines of the fish are used for the same purpose; and indeed an isinglass, of a somewhat inferior kind, may be prepared from the same parts of many other fishes. 3. Sterlet. Acipenser ruthenus.-LINN. The sterlet is the smallest species of sturgeon yet discovered: in length, it rarely exceeds three feet, and is principally found in the Caspian sea, and the adjoining rivers Volga and Ural: it is also found, though much less frequently, in the Baltic sea. It is said to have been introduced into some of the large lakes of Sweden by Frederick the first; and into some parts of Brandenburg and Pomerania, by the King of Prussia. The head of this species is longer in proportion than in other sturgeons, and flattened both above and below the body rather more slender; and the bony shields with which the upper parts are covered, less protuberant, and of a thinner substance: along the belly are also disposed two ranges of small, flat shields: the general colour is dusky above; whitish, and variegated with rose-coloured spots beneath the rows of tubercles are of a yellow cast, and the whole skin is slightly roughened into a kind of scaly appearance: the ventral and anal fins, are of a deep rose-colour: the rest blueish-brown: the usual number of shields, or tubercles, is, according to Dr. Bloch, fourteen along the back, and fifty-nine along each side. The sterlet is in much higher esteem, as an article of food, than any other species, and is even considered as one of the most delicate of fishes. Sterlet-soup, it is well known, formed one of the favourite luxuries of that gigantic epicure, Prince Potemkin, of Russia; who, in seasons when the fish happened to be dear, was content to purchase it at a price so extravagant, that a single tureen, forming the mere prelude to his repast, stood him in the sum of 800 rubles! The sterlet indeed, in Russia, makes its appearance chiefly at the entertainments of the higher nobility; and the caviare, prepared from its roe, is said to be confined, almost exclusively, to the use of the royal table. Like the rest of this genus, it is a prolific fish, and usually spawns in the months of May and June: it is said to live on worms and small fishes, and is particularly fond of the roe of the common sturgeon, for which reason, it often follows that species in its migrations. [Shaw. SECTION XVII. Large Shark. Squalus corcharias.-LINN. THE animals of the shark genus are altogether marine, and are said to be much rarer in the Baltic than any other sea: they are viviparous, and are observed to produce more young at a time than the rays, but each included, as in those fishes, in a quadrangular capsule, or involucrum, each extremity of which is extended into a long, contorted, cartilaginous thread of great length. Many of the sharks are said to emit a phosphoric light during the night: they are chiefly of a solitary nature; and, in general, devour with indiscriminating voracity, almost every animal substance, whether living or dead some few species, however, are observed to feed chiefly on fuci, and other marine vegetables. The great or white shark, so remarkable for its vast size, and its powers of destruction, is an inhabitant of most parts of the globe, though much more frequently seen in the warmer than the colder latitudes it is said to reside, principally, in the depths of the ocean, from whence it rises, at intervals, in order to prowl for prey, and is considered as the most voracious of all the inhabitants of the deep. It arrives at the length of more than thirty feet, and is of a somewhat thicker or broader form than most of the genus: the head is of a depressed shape, and broad; terminating in front in an obtusely pointed snout: the mouth is of vast width, and furnished, on the margin of each jaw, with from three to six rows of strong, flat, triangular, sharp-pointed, and finely-serrated teeth, which are so imbedded in their investing cartilage, as to be either raised or de-. pressed at pleasure: the tongue is broad, thick, and cartilaginous, : and the throat extremely wide: the eyes, as in most of the genus, of a blueish or greenish cast, rather small, and half overhung by their skinny veil: the pectoral fins are large, strong, broad, and pointed: the first dorsal fin moderately large, somewhat falcated behind, and pointed; the second is situated very low on the back, near the origin of the tail, which is slightly lengthened, and of a bilobate shape, the upper lobe or division slightly pointed, and the lower or terminal lobe rather rounded: so great is the strength of this part, that even a young shark, of about six feet in length, is able, by a stroke of its tail, to break a man's leg; it is usual, therefore, with sailors, to cut off the tail the instant they drag a shark on board the anal fin is placed somewhat beyond the middle of the abdomen, and is of a moderate size, and of a somewhat square outline the general colour of the whole animal is a pale or whitish asb, darker or brower on the upper parts; the mouth is situated considerably beneath the front, for which reason the animal is said, like most others of this genus, to be obliged to turn on its back in order to seize its prey; an observation as ancient as the days of Pliny, "resupinati vorant: affert moram providentia Naturæ, quia nisi resupini atque conversi, non corripiunt." Plin. lib. 9. c. 8. This, however, is much doubted by Dr. Bloch, who rather supposes the shark to seize its prey in a direct position, or like the generality of fishes. The skin of the shark is very rough, and is used as a kind of shagreen, as well as for smoothing various kinds of wood-work, &c. and from the liver is drawn a great quantity of oil. "Sharks," says Mr. Pennant, " are the dread of sailors in all hot climates, where they constantly attend the ships, in expectation of what may drop overboard: a man that has that misfortune perishes without redemption: they have been seen to dart at him like gudgeons to a worm." They are said to attack Negroes in preference to Europeans; and are observed, in particular, to attend, with unremitting assiduity, the passage of the slave-ships from the coasts of Africa to the West-Indian islands; and, as Cepede very happily and justly observes, may be considered as forming a proper escort to the cruel conductors of those most accursed vessels. "A master of a Guinea-ship," says Pennant," informed me, that a rage of suicide prevailed among his new-bought slaves, from a notion the unhappy creatures had, that after death, they should be restored to their fa |