Although the snail and the slug belong | furrows to the gasteropoda, we shall have little or nothing to say of them in this paper, since they and their friends are provided with pulmonary sacs or air-cavities, which enable them to breathe on land, and are not dwellers in the deep at all. The sea-snails (or gasteropods) are to be found on almost every variety of shore, inhabiting different zones of depth, from high-water mark to the deep-sea bottom. The pretty, many-coloured, ridged winkle congregates in hollows of the rock, scarcely within reach of the spray, except at springtides. The limpet adheres by thousands but a little lower. On the boulders, about half-tide level, the purple and one or two species of trochus (or top-shells) may be seen. Lower still, to the verge of extreme low tide, we find the purple-spotted trochus, the ridged and furrowed rock-shell, the dog-winkle, the chitons (looking like the millepedes of our gardens) and the lovely little cowry enveloped in its variegated mantle. If we turn over stones at the water's edge, especially in spring, we may find the sea-lemon, the lovely Eolis coronata, and other naked-gilled creatures, which resort thither to lay their coils of spawn, the pleuro-branchus, and the great purple sea-hare, which stains the stones with its rich crimson dye. The sea-snails possess a mouth surrounded with contractile lips, and sometimes armed with horny teeth in the palate. They seem also to have very acute organs of smell, since animal substances let down in a net to the bottom often draw thousands together in one night. With these facilities they rasp their way through the shells of mussels, or feast upon dead animals which chance may throw in their way; while in their turn they serve as food to the sea-stars, which swallow the young fry and seize the full-grown individuals with their long arms. You are probably familiar with a little shell, elegantly marked all over with transverse ridges, and varying in size from that of a split-pea to that of a large horse-bean. It is to be picked up on every sandy beach, and is called the furrowed cowry. The are purplish or flesh-colour, the ridges are porcellainous white; the larger. specimens commonly display three spots of dark brown, arranged lengthwise. When tenanted by its living inhabitant, and crawling at ease in clear water,-its foot spreading out to twice the extent of the base of the shell, its mantle turned up and covering the shell, its head (armed with two straight long tentacles) protruding from the front of the shell,-it is a very elegant creature. The furrowed cowry is the only species that lives in the British seas, but about 150 species are known to exist, and most of them are valued as ornaments. The beauty arises in part from the small amount of animal matter which the shells contain, but depends still more on the deposit of a layer of shelly matter over the whole exterior, when the mantle is clasped around it. In the young cowry, before this final deposit of nacre or pearl has taken place, the edge of the shell is sharper, the mouth wider, and the spiral structure more apparent. There is a small species known by the name of the money cowry, which is dredged in the Pacific and Eastern seas, and is the current coin of the natives of Siam, Bengal, and many parts of Africa. In Bengal 3,200 of these shells are reckoned to be equivalent to a rupee, or about two shillings of English money. Several hundred tons of cowries are annually imported into Liverpool, for the purpose of carrying on trade with West Africa. In the Friendly Islands permission to wear the orange cowry as an ornament is only granted to persons of the highest rank. The shape of the shell in the cones is indicated by their name. They are generally very beautifully coloured, and some species are so highly valued that so high a price as 300 guineas has been given for a single specimen. The animals are very predatory in their habits, and some of them are said to bite the hands of their captors. The volutes are also remarkable for their beauty of form and colouring, and are much sought after by collectors. Come we now to the whelks, concerning which you will, perhaps, be able to testify from experience, both as to the taste of the | sometimes been supposed that the Roman animal and the absence of brilliant colours in the shell. The shells, however, present many interesting varieties of form and marking, and the animals are worth attention for their structure and habits. They have a trunk, which they can not only bend in all directions but withdraw entirely into the body, just as when the finger of a glove is pushed back into the part that covers the palm. As this proboscis incloses a tongue furnished with a hundred rows of sharp teeth, the animal is able to file his way into the hardest shell. Burrowing in the sand in chase of hapless bivalves, he bores a hole (cunning fellow!) close to the hinge where the fish is, and then sucks out their life. Look at this old valve of a mactra. Like hundreds more that you may pick up at high-water mark, it is perforated in the place described, the hole so smooth and so perfectly circular that you would suppose a clever artizan had been at work drilling the massive stony shell with his steel wimble. These carnivorous molluscs are not restricted in their destructive operations by any ties of kindred, by any fine notions of morality, for the shell of the whelk itself is not unfrequently found perforated, just as if by one of its own species. Mr. Lewis one day threw a good-sized whelk into a vase, in which was a hermitcrab, destitute of a shell. Pagurus clutched the shell at once and poked in his interrogatory claw, which, touching the operculum of the whelk, made that animal withdraw and leave an empty space, into which Pagurus popped his tail. In a few minutes the whelk, tired of this confinement in his own house, and all alarm being over, began to protrude himself, and in doing so gently pushed the crab before him. In vain did the intruder, feeling himself slipping, cling fiercely to the shell; with slow but irresistible pressure the mollusc ejected him. This was repeated several times, till at length Pagurus gave up in despair. To this family also belongs the helmetshell-one of the largest of the gasteropods, the shell of which is beautifully sculptured by Italian artists in imitation of antique cameos and the purpura, from which it has purple dye was obtained. Certainly a beautiful purple colour is frequently observed on the nacre, in the throat of the various species of purpura; and the purpuro lapillus, a small shell found very abundantly on our own shores, has the power of secreting this dye. Such was the estimation in which this dye was held at one time that, amongst more than one of the nations of antiquity, it was death for any one but the sovereign or supreme judges to wear gar. ments dyed with Tyrian purple. With the Romans the purple was indicative of sovereign power, and their emperors alone were permitted to wear it. The dye, which was extracted by breaking the shells of the purpura, was often mixed with other substances, which brought out more brilliantly the natural colour. The curious eggs of these creatures may sometimes be found in clusters, affixed to little stones, and indeed, when first deposited, some of them seem always to be thus anchored, affording support to others, which stand, acrobat fashion, on the shoulders of the first. It is proper to say that, in the opinion of some, the Tyrian purple was obtained from a species of murex, or rock-shells, the animals of which closely resemble the ordinary whelks. Mr. Gosse says there is little doubt that the purpura is one of the animals enumerated by Pliny as used by the ancients for obtaining this dye; though the principal and that which yielded the richest hue was probably the murex trunculus, a common Mediterranean shell, which does not extend to our shores. The old myth relating to the discovery of the purple dye tells us that the Tyrian Hercules was one day walking with his sweetheart along the shore, followed by her lap-dog, when the playful animal seized a shell that had just been washed up on the beach. were presently dyed with a gorgeous purple tint, which was traceable to a juice that was pressed out of the shell-fish. The lady was charmed with the colour, and longed to have a dress of it, and, as wishes under such circumstances are laws, the enamoured hero set himself to gratify her, and soon succeeded in extracting and applying the dye Its lips which afterwards became so famous. The shell of one species of murex is employed as a lamp in the Shetland cottages; being suspended horizontally and filled with oil, when the canal projecting straight from the front of the shell serves for the reception of the wick. One of the largest of the mollusca is the strombus gigas of the West Indies, whose shell often measures a foot in length, and weighs several pounds. The shelly matter of the interior, which exhibits beautiful pink tints, is much used in the manufacture of cameos, and immense numbers of the shells are imported into this country for that purpose. Coming again to our periwinkles, which belong to the great family of the turritellida, we shall never vote them to be "not worth a pin" when we find them doing service as barometers. The Swedish peasants have observed that whenever the periwinkles ascend the rocks it is a sure sign of a storm being at hand, their instinct having taught them to place themselves out of the reach of the dashing of the waves. When, on the contrary, they make a descent upon the sand, it is an indication of a calm. The periwinkle is even worth notice for its prettiness, as it exhibits itself when crawling upon the glass of an aquarium, or on the seaweeds where it finds its food. The body is prettily banded with multitudes of narrow dark markings, and the mode in which the creature slides itself over the glass is very curious. The true turritella have an elongated spiral shell, with a small opening. The wentle-trap is a very pretty shell, found in tolerable profusion on our sands. A specimen of the royal staircase wentle-trap would formerly fetch eighty or ninety pounds. Besides these shells, the construction of which preserves the usual spiral order, some of the molluscs of this family form an irregularly tabular habitation. Of these the vermetus is remarkable for the close resemblance of its shell to that of the serpula; but when perfect, it may be generally distinguished by the regularly spiral twisting of its first-formed portion. Among the turbinidæ, or top-shells, we may give a few minutes' attention to the trochus. It is not often that the top-shaped shells are found perfect, for they are generally worn away at the apex, so that the colouring substance is removed, and the point of the shell is white. But the shells are to be found plentifully on every coast, either empty and cast ashore by the waves, or living and adhering to the seaweeds that are laid bare at low water. Here, for instance, is a purple-spotted top. Before we take him up, let us notice for a moment with what an easy, even movement he glides along over the leaves of the seaweed, now over the stony projections of the pool, now on the broad weeds again. On lifting the shell we find that the fine, fleshy, apricotcoloured animal clings with considerable force to the weed; and, on transferring it to a glass bottle, we get a better sight of the organ by which it maintains both its stability and its movements. When in motion it strongly reminds one of the human tongue. The shell, the solid house of stone, which our friend trochus has built up to cover his head in the hour of danger, combines the comfortable with the ornamental. Its general form is that of a cone of much regularity, but with an oblique base; this conical form being the result of the winding of a very long cone upon itself in a spire. If you examine a dead shell with care, you will see that this is really so. The trochus is one of our showy shells. This specimen before us has for its ground-colour a chaste, cool grey, occasionally, varied with tints of reddish buff, but most conspicuously adorned with a series of large and regular spots of purplish crimson, running along the lower angle of the spire from the base to the summit. Each of these spots passes off into an oblique line above, the repetition of which augments the beauty of the pattern. The interior of the shell has a glory of quite another character. It is covered with a coat of nacre, or pearl, of exceedingly brilliant and rich lustre; and the presence of this inward pearliness is quite characteristic of the genus, and of most others belonging to the same family—the turbinidæ. Many of the fine large tropical species are specially conspicuous for this adornment. De Mont fort mentions a necklace, which he had seen, that was made out of the nacral part of the shell of a turbo, and which was much more brilliant and beautiful than any of the finest Orient pearls. A trochus in an aquarium will perform the part of a mower, using its tongue as a scythe, and cutting down the green film of vegetation that forms on the glass. There is a small shell extensively employed for ornamental purposes, and known under the name of " Venetian shells." They are used for making studs, necklaces, bracelets, and pins, and really form a very beautiful ornament. This shell is a small univalve, not unlike the trochus, and is referred by Dr. Lankester to the genus Phasianella. The nacre is very brilliant, assuming various tints of blue and purple. Species of the creature are found in the Mediterranean Sea, and it is from this fact that they may have found their way to Venice, and thus to England, with their ordinary name. Shells of this kind are also brought from Australia; and in the South Kensington Museum are several strings of them, which are said to be used by the natives of Tasmania as ornaments. Ianthina is a pretty name, belonging to a creature possessing a beautiful snail-like shell, and from this circumstance, and the fine violet at the base of its shell, receiving the name of violet snail. When irritated or alarmed, the ianthina pours out a violet fluid, which darkens the water around it, and thus serves for its concealment, in the manner of the ink of the cuttle-fish. But the most remarkable circumstance in the history of this delicate and beautiful creature consists in its production of a peculiar float or raft, composed of numerous gristly little vessels filled with air, which springs from the small foot, in place of an operculum. To the lower surface of this curious float the eggcapsules are attached, and thus the ianthina carries its offspring about with it until the young animals are fully formed. The ianthing inhabit the Mediterranean and the warmer parts of the Atlantic Ocean. The shores of the islands of St. Helena and Ascension are sometimes completely covered with them. When the sea is quiet, they appear in vast shoals on the surface, with their foot turned upwards; but as soon as the winds ruffle the ocean they empty their air-cells and sink to the bottom. Another beautiful gasteropod is the earshell, in which the colours present great variety and richness. Its shell, when the surface is polished, possesses a pearly lustre, with resplendent metallic hues. It is consequently in high esteem as an ornament. The animal attaches itself to the rock, after the manner of the limpet, holding on by its large muscular foot with such force that considerable strength is required to detach it. When it is undisturbed, the shell is usually a little separated from the rock; and the best mode of securing the animal is to place some instrument under its edge, and endeavour to remove it before the creature is alarmed. Sometimes, when the hand has been thus used under water, and not with sufficient caution, the shell has been drawn down firmly upon it, and fatal results have followed. Another gasteropod, noted for the firmness of its hold, is the limpet, whose shell is one of the commonest found on the seashore. The adhesion is caused by atmospheric pressure, just as with a boy's sucker; for the limpet is enabled to raise the centre of that part of the body that rests on the rock, while the edge is closely pressed upon it. The firmness of hold is also increased by the fact that, after the animal has remained for some time in one spot, it forms a hollow, into which the shell sinks, so that there is no possibility of reaching its edge. It would almost seem indeed too tight a fit to allow limpet himself to stir, but as he is exclusively a vegetarian in his diet, he must manage in some way to get his daily dinner of greens. A peering naturalist, out one night upon his sea-side prowlings, with a bull's-eye lantern at his girdle-much to the mystification, no doubt, of the coast-guard watching on the cliffs above-observed the strange phenomenon of old aldermanic limpets crawling hither and thither, with tilted shells, about the tender mossy green that grew in patches on the rocks. He was curious enough to mark their movements, and found that, as morning approached, the limpets, in a comfortable state of repletion, glided away from the mossy patch, and be- | undergone preparatory digestion, it has to took themselves, with unerring precision, be further ground by these teeth. This each to his own hollow in the stone, into strange animal, as harmless as a butterfly, which he settled himself as snugly as if he used to be considered a mischievous creature had never moved at all. -a prejudice perhaps resulting from man's propensity to associate evil habits with an unprepossessing appearance, as though either beauty or ugliness were more than skin-deep! The Romans believed that the mere sight of the sea-hare caused sicknesssometimes death. Apuleius happened to have a curiosity about this animal, for which he was accused of magic. The foolhardy meddler who handled the animal swelled, and possibly burst in consequence; at any rate his hair fell from his head and chin. Subtle poisons were concocted from its slimy corpse. But all modern naturalists of reputation who have examined the seahare about its poisonous qualities, have agreed to pronounce it guiltless of the crimes laid to its charge. The whelk is not alone in the possession of a wondrous rasp-like tongue. Many of the sea-snails are furnished with ribbonshaped tongues, studded with microscopic teeth, which exhibit such regular and constant shapes that a mere inspection of a fragment of a tongue will enable the naturalist to pronounce to a certainty upon the affinities of the creature to which it belonged. From an ordinary individual of the common limpet, a tongue two inches in length may be extracted, armed with no fewer than 150 or more bands of denticles, twelve in each row, so that in all it may possess nearly 2,000 teeth. The limpet uses this elaborate organ as a rasp with which to reduce to small particles the substance of the seaweeds upon which it feeds. In some of our common garden-slugs as many as 20,000 teeth may be counted. Wonderful, indeed, is this complication of minute organisms! The sea-ears, or tooth-shells, are very handsome mother-of-pearl shells, frequently used for the inlaying of boxes. They are curved and tapering, resembling the tusk of an elephant, with an opening at each end, and a surface sometimes smooth, sometimes striated. If the spiral shells could be drawn out, they would all be found to consist of a tube, gradually widening from the apex to the base; so that the tooth-shell only differs from its fellows in not being wound into whorls. The animals are carnivorous, and are found in most seas, inhabiting a sandy or muddy bottom. The aplysia, or sea-hares, are such queerlooking creatures that one would fancy them to be great naked snails or slugs ridiculously metamorphosed. If they had begun by being slugs, and then thought of changing into hares, and next resolved to be camels, and after all had contented themselves with their original low estate, we could understand the absurd shape they have got into. The teeth of the sea-hare are in one of its stomachs, and in that one which is farthest from the mouth, so that after the food has Around Weymouth, where the aplysia is common, the fishermen and shore-boys call it the sea-cow. To this they are guided, as indeed are those who call it the sea-hare, by the pair of tentacles which stand erect, but a little diverging from the back of the head, and look somewhat like a hare's ears. When full-grown the animal is three inches in length and upwards of an inch high. Its figure, when it crawls, scarcely exhibits the same outline for two minutes together. See what has happened! "On dropping one of the slimy beasts into this phial of clear sea-water," says Mr. Gosse, "it immediately resented the incarceration by beginning to pour out from beneath the lobes of the mantle a thin stream of fluid of the most royal purple hue, which freely diffused itself through the water. And see! It is still copiously exuding; and the whole contents of the bottle are now fast becoming of so fine and rich a tinge, as already to veil the form of the animal." We come now to the nudibranchiate or naked-gilled gasteropods. The shell possessed by the embryo animals is shed early, and never replaced. The animals are found on all rocky coasts, where they usually inhabit rather deep water, creeping about upon sea-weeds, and occasionally swimming. |