found nothing but ingratitude from man, and though his industry was apparently becoming fatal to himself. From him I will take some of the leading features in the history of those animals which breed in shells; previously taking my division from Aristotle, who, as was said above, divides them into three classes: the Turbinated, or those of the Snail kind; the Bivalved, or those of the Oyster kind; and the Multivalved, or those of the Acorn-shell kind. Of each I will treat in distinct chapters.

CHAPTER V.

OF TURBINATED SHELL-fish of THE SNAIL KIND.

To conceive the manner in which those animals subsist that are hid from us at the bottom of the deep, we must again have recourse to one of a similar nature and formation that we know. The history of the garden snail has been more copiously considered than that of the elephant; and its anatomy is as well if not better known: however, not to give any one object more room in the general picture of nature than it is entitled to, it will be sufficient to observe, that the snail is surprisingly fitted for the life it is formed to lead. It is furnished with the organs of life in a manner almost as complete as the largest animal; with a tongue, brain, salival ducts, glands, nerves, stomach, and intestines; liver, heart, and blood-vessels: besides this, it has a purple bag that furnishes a red matter to different parts of the body, together with strong muscles that hold it to the shell, and which are hardened, like tendons, at their insertion.

But these it possesses in common with other ani

mals. We must now see what it has peculiar to itself The first striking peculiarity is, that the animal has got its eyes on the points of its largest horns. When the snail is in motion, four horns are distinctly seen; but the two uppermost and longest deserve peculiar consideration, both on account of the various motions with which they are endued, as well as their having their eyes fixed at the extreme ends of them. These appear like two blackish points at their ends. When considered as taken out of the body, they are of a bulbous or turnip-like figure; they have but one coat; and the three humours which are common in the eyes of other animals, namely, the vitreous, the aqueous, and the crystalline, are in these very indistinctly seen. The eyes the animal can direct to different objects at pleasure, by a regular motion out of the body; and sometimes it hides them, by a very swift contraction into the belly. Under the small horns is the animal's mouth; and though it may appear too soft a substance to be furnished with teeth, yet it has not less than eight of them, with which it devours leaves, and other substances, seemingly harder than itself, and with which it sometimes bites off pieces of its own shell.

But what is most surprising in the formation of this animal, are the parts that serve for generation. Every snail is at once male and female, and while it impregnates another, is itself impregnated in turn. The vessels supplying the fluid for this purpose are placed chiefly in the fore-part of the neck, and extend themselves over the body; but the male and female organs of generation are always found united, and growing together. There is a large opening on the right side of the neck, which serves for very different purposes. As an anus it gives a passage to the excrements; as a mouth it serves for an opening for respiration; and also, as an organ of generation,

it dilates when the desire of propagation begins. Within this each animal has those parts, or something similar thereto, which continue the kind.

For some days before coition the snails gather together, and lie near each other, eating very little in. the mean time; but they settle their bodies in such a posture that the neck and head are placed upright. In the mean time, the apertures on the side of the neck being greatly dilated, two organs resembling intestines are seen issuing from them, which some have thought to be the instruments of generation. Beside the protrusion of these, each animal is possessed of another peculiarity; for from the same aperture they launch forth a kind of dart at each other, which is pretty hard, barbed, and ending in a very sharp point. This is performed when the apertures approach each other; and then the one is seen to shoot its weapon, which is received by the other, though it sometimes falls to the ground: some minutes after, the snail which received the weapon darts one of its own at its antagonist, which is received in like manner. They then softly approach still nearer, and apply their bodies one to the other, as closely as the palms and fingers of the hands when grasped together. At that time the horns are seen variously moving in all directions, and this sometimes for three days together. The coupling of these animals is generally thrice repeated, at intervals of fifteen days each, and at every time a new dart is mutually emitted.

At the expiration of eighteen days the snails produce their eggs at the opening of the neck, and hide them in the earth with the greatest solicitude and industry. These eggs are in great numbers, round, white, and covered with a soft shell: they are also stuck to each other by an imperceptible slime, like a bunch of grapes, of about the size of a small pea.

When the animal leaves the egg it is seen with a very small shell on its back, which has but one convolution; but in proportion as it grows, the shell increases in the number of its circles. The shell always receives its additions at the mouth, the first centre still remaining; the animal sending forth from its body that slime which hardens into a stony substance, and still is fashioned into similar volutions. The garden snail seldom exceeds four rounds and a half; but some of the sea snails arrive even at ten.

The snail thus fitted with its box, which is light and firm, finds itself defended in a very ample manner from all external injury. Whenever it is invaded, it is but retiring into this fortress, and waiting patiently till the danger is over, Nor is it possessed only of a power of retreating into its shell, but of mending it when broken. Sometimes these animals are crushed seemingly to pieces, and to all appearance utterly destroyed; yet still they set themselves to work, and in a few days mend all their numerous breaches. The same substance by which the shell is originally made, goes to the re-establishment of the ruined habitation. But all the junctures are very easily seen, for they have a fresher colour than the rest, and the whole shell in some measure resembles an old coat patched with new pieces. They are sometimes seen with eight or ten of these patches, so that the damage must have been apparently irreparable. Still, however, though the animal is pos- · sessed of the power of mending its shell, it cannot when come to its full growth make a new one. Swammerdam tried the experiment: he stripped a snail of its shell, without hurting any of the bloodvessels, retaining that part of the shell where the muscles were inserted; but it died in three days af ter it was stripped of its covering, not, however, without making efforts to build up a new shell, for before

its death it pressed out a certain membrane round the whole surface of its body. This membrane was entirely of the shelly nature, and was intended by the animal as a supply towards a new one.

As the snail is furnished with all the organs of life and sensation, it is not wonderful to see it very voracious. It chiefly subsists upon the leaves of plants and trees, but is very delicate in its choice. When the animal moves to seek its food, it goes forward by means of that broad muscular skin which is sometimes seen projecting round the mouth of the shell; this is expanded before, and then contracted with a kind of undulating motion, like a man attempting to move himself forward by one arm while lying on his belly. But the snail has another advantage, by which it not only smooths and planes its way, but also can ascend in the most perpendicular direction. This is by that slimy substance with which it is so copiously furnished, and which it emits wherever it moves. Upon this slime, as upon a kind of carpet, it proceeds slowly along, without any danger of wounding its tender body against the asperities of the pavement; by means of this it moves upwards to its food upon trees, and by this descends, without danger of falling and breaking its shell by the shock.

The appetite of these animals is very great; and the damage gardeners in particular sustain from them, makes them employ every method for their ⚫ destruction. Salt will destroy them, as well as soot; but a tortoise in a garden is said to banish them much more effectually.

At the approach of winter the snail buries itself in the earth, or retires to some hole, to continue in a torpid state during the severity of the season. It is sometimes seen alone, but more frequently in company in its retreat, several being usually found together apparently deprived of life and sensation.