3. Malacopterygii sub-brachiati, or fishes with soft fins

under the gills.

4. Malacopterygii apodes, or fishes without ventral fins. 5. Lopobranchii, or fishes with tufted branchiæ.

6. Plectognathii, or fishes with the upper jaw fixed.

Chondropterygic, or Cartilaginous Fishes.

7. Cyclostomi, or fishes with jaws fixed in an immoveable ring, and with holes for the gills.

8. Selachii, or fishes with moveable jaws and holes for the gills.

9. Sturiones, with the branchiæ in the usual form.

Of the bony fishes, the Acanthropterygii, or fishes with hard spiny fins, are divided into fifteen families, the principal of which are the perch family, the mailed cheek fishes, including the gurnards, the flying fish of the Mediterranean, and the sticklebacks, or jack banticles; the mackerel family, including the tunny, bonito, and sword-fish; the pilot-fish; the dolphin of the Mediterranean, so celebrated for the beauty of its dying tints, and the celebrated john dory. Among the Malacopterygii abdominales, or soft-finned fishes, that have their ventral fins suspended from the abdomen, the most interesting are the carp family, the pike family, the flying fish of the ocean, the salmon family, and the herring family, including the sprat, pilchard, and anchovy.

The Malacopterygii sub-brachiati are soft-finned fishes, with the ventral fins beneath the pectorals; the principal of which are the cod family, including the haddock, whiting, and ling; the flat-fish family, including soles, turbots, plaice, and flounders; and the suckers or lump-fish.

The Malacopterygii apodes are confined to the eel family. The Lopobranchii include the pipe-fish, and other fishes of similar form.

The Plectognathii comprise the very singular forms of the balloon-fish and sun-fish.

The Chondropterygii, or cartilaginous fishes, are divided into only three orders; namely, the Sturiones, or sturgeon family; the Selachii, or sharks and rays, including the torpedo; and the Cyclostomi, or lamprey family.

THE MOLLUSCOUS ANIMALS

Have no bones except their shells. Their sense of feeling appears to be very acute, but the organs for the other senses are either wanting or very imperfect. The blood is cold and white, and the heart often consists of only one ventricle; a few of them have imperfect lungs, but the greater number breathe through gills. They have all the power of remaining a long time in a state of rest, and their movements are either slow or violently laborious. Some of them appear incapable of locomotion. They produce their young from eggs; but some lay their eggs on a part of their own body, where the young are hatched. The following are Cuvier's six

classes:

These animals

1. Cephalopoda, or head-footed Mollusca. are furnished with long fleshy arms or feet, proceeding from the head, which is distinct. There is only one order, which includes the cuttle-fish, nautilus, and belemnites.

2. Pteropoda, or wing-footed Mollusca. These animals have two membranous feet or arms proceeding from the neck. There is only one order, which contains six genera, the best known of which is hyalæa, the shell of which is commonly called Venus's chariot.

3. Gasteropodo, or body-footed Mollusca. All these animals crawl with the flat part of the body, which acts as a kind of sucker. There are nine orders; but the common snail will give an idea of the habits of the class.

4. Acephala, or headless Mollusca.

These animals have two shells united by a hinge, and no distinct head, like the oyster. There are two orders.

5. Brachiopoda, or arm-footed Mollusca. have two shells not united by a hinge. orders.

These animals

There are two

These animals

6. Cirrhopodes, or fringed-footed Mollusca. are soft and headless, like the oyster, but they are furnished with fringe or hair, like tentacula; as, for example, the lepas or barnacle.

It must be observed, that the system of Cuvier is not generally adopted in classing shells, as his classes are formed from the animals alone, and we have many shells, the animals

of which are unknown; and that of Lamarck is preferred, as he founds his classes partly on the animals and partly on the shells. Lamarck divides the species into three classes, namely, Cirrhipeda, Conchifera, and Mollusca. The first is the same as the sixth class of Cuvier; the Conchiferæ are acephalous, or headless, and two-shelled or bivalves, like the oyster; and the Mollusca are univalves and cephalous, that is, they have only one shell, and a kind of head like the snail.

CHEMISTRY, &c.

[INSTEAD of furnishing in this and the next Number our usual chemical dialogue or conversation, we shall insert a somewhat copious extract from a valuable paper which appeared in the " Edinburgh Review," for January, 1845, entitled, "Progress of Scientific Agriculture." We were much struck by the whole article, as opening out a subject as important as it is wonderful. Who can tell the extent to which a better acquaintance with the principles of chemistry, and their proper mode of application to agricultural purposes, shall increase the fertility of our land, and the quantity of nutrition contained in the produce? The paragraphs we extract, will show the important connexion between chemistry and agriculture; and illustrate, at the same time, the marvellous wisdom of God. Wherever we direct our attention, we find in nature a system of designs, adaptations, and contrivances. It is not merely a collection of systems, each independent of the other, but a system of systems,—one system implying other subordinate ones, and each, perhaps, containing others. The more the works of God are considered, the more plainly do we see personal intention and arrangement. Some of the first and strongest laws of our mental constitution deceive us, if this is not the case. Take a steam-boat. There is the boat itself, adapted for floating, and containing passengers and goods. There is the steam-engine, adapted to the production of power. But the boat is suited to the engine, and the engine to the boat. This may serve to explain our meaning. Who would suppose a steam-boat to be a natural

developement? Who could suppose it, till he had disarranged all his original, natural modes of thinking, and put them together in a way suited to his present purpose; making himself able to think that there is no such thing as design in nature, but that all is developement? Even then his work would not be done. All men must learn the same method. And then, how long could society exist? All falsehood is disruptive and ruinous.]

ALL vegetable productions contain from ninety to ninetyeight per cent. of combustible or organic matter; and this has been found, in all cases, to contain three different classes of substances:

First, the starch class; which comprehends starch, gum, and sugar, and certain other substances of a similar kind.

Second, the fatty class; which comprehends solid and liquid oils of various kinds, of which the oils extracted from seeds and nuts are familiar examples.

Third, the gluten class; which comprehends the gluten of wheat, vegetable albumen, vegetable casein, and some other analogous substances, the distinctive characters of which have not as yet been thoroughly investigated.

These several classes of substances are always to be found in sensible quantity in all our cultivated crops; but their proportions vary in different plants, in different parts of the same plant, and in the same part when the plants are grown in different climates, on unlike soils, or by the aid of different manures. Hence the occasional differences in the sensible qualities of the same vegetable, under different circumstances, -the waxiness of the potatoe, the hardness of the pea, and the stubbornness of the barley, become intelligible. The several organic constituents of the grain and root crops are

* When wheaten flour is made into a dough with water, and this dough is washed with a stream of water upon a sieve, as long as the water passes through milky, a tenacious substance, like bird-lime, remains behind. This is the gluten of wheat. Albumen is the name given by chemists to the white of the egg; and casein, that applied to the curd of milk. Of both of these latter, an appreciable quantity is found in almost every kind of vegetable food.

present in unlike proportions, and necessarily give rise to unlike qualities.

But their unlike effects, in the feeding of animals, suggested a further train of investigation. The parts of animals are known to be differently built up, or with different degrees of rapidity and success, by these different varieties of vegetable produce;―of what, then, do the parts of animals themselves consist? The answer to this question throws a new and beautiful light upon our path, clearing up obscure points on the way we have already trodden, and pointing out new tracks, which it will prove interesting hereafter still further to explore.

All animal substances-the flesh, bones, and milk, of all living creatures-consist, like the soil and the plant, of a combustible and an incombustible part. In dry muscle and blood, the incombustible or inorganic part does not exceed two per cent., and in milk evaporated to dryness, seven per cent.; while in dry bone it amounts to about sixty-six per cent. of the whole weight.

The combustible or organic part consists of fibrin,—the fibrous part of lean meat is so called, and of fat. And rigorous analysis appears to show, that this fibrin is almost identical in constitution with the pure gluten of wheat; while the fat of some animals at least, is absolutely identical with the fatty oils contained in certain vegetable productions.

The incombustible part, again, consists of soluble saline substances, and of an insoluble earthy matter, the earth of bones. These two classes of inorganic substances exist also in the ash of all plants, though in variable proportions. The stems and leaves abound more in soluble saline matter, the seeds in bone-earth and other phosphates.

These things being discovered, the uses of the several constituents of the food become in some degree manifest. The fat of the animal was derived directly from the fat of the vegetables on which it lived, its muscular fibre directly from the gluten of its food, and the salts of its blood, and the earth of its bones, from the inorganic matters contained in the ash of the plants on which it fed. The plant produced the