Beautiful shells

We have insensibly passed from the Bivalve shells to those composed of several pieces, and therefore called Multivalves; properly, perhaps, the Rock-borers, last described, come into this division, for although their covering consists mainly of two principal portions or valves, yet there are often additional parts; in some a calcarious tube envelopes the whole mollusk, leaving only an opening behind; this is more especially the case with those which most resemble worms, such as the genera Teredina and Teredo, included by Lamarck in the family which he calls Tubulidæ.

The first group of multivalves we shall have to notice, are

THE CHITONS,

forming the family Chitonidæ. The term has a Greek derivation, and means a coat of mail. These mollusks are covered by a shell formed of eight distinct portions, arranged along the back in a single row, and attached to a mantle which resembles leather, being very tough and wrinkled; the edges of this mantle extend beyond the borders of the plates, which overlap each other, so as to constitute a kind of armour, very different from the conical shell of the Limpit, or the turbinated, that is twisted, case of some of the Borers. The coverings of the Chitons are variously marked, so that each distinct species is known by its peculiar pattern, as a knight of old by the quarterings of his shield. All the mantles, however, have scaly, hairy, or spiny margins. In this coat of mail, the animal can roll itself up like an armadillo, and so be tolerably secure from its enemies; it has an oval foot, the sides of which are covered with small leaflets, and by means of this it can attach itself to rocks, like the Limpit, or travel about in search of adventures. It has no distinct head, therefore it is acephalous; nor any perceptible eyes. The mouth is furnished with a long tongue, curled up spirally, like a watch-spring, and armed with horny teeth.

The members of the Chiton family are numerous, being found on most rocky shores; they attain the largest size in the hottest climates, having never been found very far north. The British species are small, and not more than two or three in number; they may be found adhering to stones near low-water mark. We give a figure of one of these called the Tufted Chiton, (C. fascicularis;) this word is from the Latin fasciculus—a little bundle of leaves or flowers, and it refers to the hairy tufts that edge the mantle of this marine slug.

BARNACLES,

Or, as they are sometimes called, Bernicles, belong to what naturalists term the class Cirrhopoda, sometimes spelled cirripeda, which appears to be derived from the Latin cirrus—a tuft or lock of hair curled, and pede—a foot; hence the term may be translated hairy-footed. Such of our readers as have seen the Common or Duck Barnacle, (Pentalasmis anatifera,) will at once understand the applicability of this term. Many a piece of drift wood comes to land literally covered with long fleshy stalks, generally of a purplish red colour, twisting and curling in all directions, and terminating in delicate porcelain-like shells, clear and brittle, of a white colour, just tinged with blue, from between which project the many-jointed cirrhi, or hair-like tentacles, which serve the purpose of a casting net, to seize and drag to the mouth of the animal, its prey, which consists of small mollusks and crustacea.

This is the Barnacle about which such strange stories are told by old writers, who affirmed that the Barnacle or Brent Goose, that in winter visits our shores, is produced from these fleshy foot-stalks and hairy shells by a natural process of growth, or, as some philosophers of our day would say, of development. Gerard, who, in 1597, wrote a “Historie of Plants,” describes the process by which the fish is transformed into the bird; telling his readers that as “the shells gape, the legs hang out, that the bird growing bigger and bigger the shells open more and more, till at length it is attached only by the bill, soon after which it drops into the sea; there it acquires feathers, and grows to a fowle.” There is an amusing illustration given in Gerard’s book, where the young Geese are represented hanging on the branches of trees, just ready to drop into the water, where a number of those that have previously fallen, like ripe fruit, and attained their full plumage, are sailing about very contentedly. It was part of this theory that the Barnacles were of vegetable origin, they grew upon trees, or sprung out of the ground like mushrooms; so we find in the works of an old poet named Du Bartas, these lines:—

The investigations of modern science have quite exploded this foolish notion; we now know exactly what transformations the Barnacle undergoes; strange enough some of them are, but it does not change into a Goose, although its specific name has reference to that bird, being derived from anas, the Latin for Goose.

The shell of the Barnacle is composed of five pieces joined together by membranes; four pieces are lateral, that is to say, they form the sides, the word comes from the Latin latus—a side; the other is a single narrow slip, which fills what would otherwise be an open space down the back between the valves; these parts of the shell appear to be somewhat loosely connected, so as to allow free action to the animal lodged within, which is enclosed in a fine skin or mantle. The mouth is placed at the lower part, near the opening, whence the cirrhi issue forth; this mouth is a curious piece of mechanism, being furnished with a horny lip covered with minute palpi, or feelers; there are three pairs of mandibles, that is jaws, the two outer ones being horny and serrated, that is jagged or toothed like a saw; the inner one is soft and membranous, that is, composed of little fibres, like strings, crossing each other, as we see what are called the veins in a leaf.

Much more might be said about the internal structure of the Cirrhopods, or Balani, as the Barnacle group is sometimes called, from the Latin Balanus—a kind of acorn. By some naturalists, the term is not applied to the stalked Cirrhipoda, like that we have been describing, but only to the sessile kinds, that is, those which set close or grow low; from the same Latin root comes the English word session—a settling. The coverings of these Dwarf Barnacles are sometimes called acorn shells; they are commonly white, of an irregular cone shape, composed of several ribbed pieces, closely fitted together with an opening at the top, closed by an operculum, or stopper.

These shells cover in patches the surface of exposed rocks, drift wood, and any other substance. Some of the mollusks affix themselves to the bodies of Whales, others form a lodgment in the hollows of corals and sponges. Once fixed they remain so during life, taking their chance of such suitable food as may come within their limited sphere of action. At an earlier stage of their existence, both their shape and habits are very different, being lively little creatures, swimming about hither and thither like water-fleas. They are about the tenth of an inch long, and of most grotesque appearance, having six jointed legs set with hairs, the whole being so arranged that they act in concert, and striking or flapping the water, send the little body along in a series of bounds; then the creature has two long arms, each furnished with hooks and a sucker, and a tail tipped with bristles, which is usually folded up under the body; its pair of large staring eyes are pedunculated, that is, set upon foot-stalks; it has a house on its back, like a bivalve shell, into which it can collect its scattered members when occasion requires. When of sufficient age to settle itself in life, and become a staid member of submarine society, it fixes itself to some convenient object, throws away its eyes as no longer useful, gets rid of its preposterous limbs, enlarges its house, and sits down to fishing in a small way for an honest and respectable livelihood.

A piece of timber covered with Stalked Barnacles, wriggling and twisting about like so many helmeted snakes, and waving their plume-like cirrhi, is a very curious sight. They sometimes attach themselves to ship’s bottoms in such numbers as to retard their progress through the water; they do not, however, bore into and destroy the timber, like the Teredines, or ship worms, to which we have alluded in our brief notice of the Pholadæ. The growth of Barnacles must be very rapid, as a ship perfectly free from them, will often return after a short voyage, with her bottom below the water line completely covered.

We give a representation of a group of these stalked mollusks, as they appear affixed to a piece of timber. This is the Common, or Duck Barnacle.

CUTTLE FISH.

Strange and monstrous as are the forms of many of the creatures that inhabit the deep, there are perhaps none more so than those belonging to that division of the class Cephalopoda, called Sepia or Cuttle-fish. But before we go any further let us enquire what is meant by a Cephalopod. Our readers have already learned that Gasteropod means stomach and foot, and that acephalous means headless; now here we have a word which takes a portion of each of the others, cephal—head, and peda, or poda—a foot, consequently ceph-a-lo-po-da, is a class of molluscous animals which have their feet, or organs of motion, arranged around the head, something, you may suppose, like that celebrated hero of nursery rhymes,

Only our bag-shaped Mr. Sepia, with his great round staring eyes, and numerous legs or arms, whichever you please to call them, all twisting and twining about like so many serpents, is a much more formidable looking individual. A strange fellow is this altogether; he has a shell, but he does not use it for a covering, he carries it inside of him, and it serves the purpose of a sort of back-bone; it is horny and calcarious, light and porous, as our readers well know, having most likely often used it to take out unsightly blots, or erase mistakes in their copy or cyphering books.

When Mr. Sepia walks abroad, he sticks his little round body upright, so that his eyes, and mouth, which is armed with a parrot-like beak, are brought close to the surface over which he passes, while his long twining legs go sprawling about in all directions; on the insides of these legs are a great number of small circular suckers, by means of which the animal can fix itself to any object so tightly that it is almost impossible to detach it without tearing off part of the limb. Woe be to the poor unfortunate fish that chances to come in its way; the snaky arms are thrown around it, and made fast, and away goes the cephalopod for a ride, eating on the road to lose no time, on the finny steed that carries it. In some species each of the suckers has a hook in the centre, which of course renders the hold yet firmer, and no doubt adds to the disagreeable sensation which their tight compression must cause; it is likely that these hooks are intended to retain the hold of soft and slippery prey, which might otherwise be too agile for the “ugly customer,” that would affectionately embrace it. But Mr. Sepia, though well armed in front, is rather open to attacks in the rear of his soft naked body; to provide for such an emergency, he is furnished with a little bag of inky fluid, which he squirts out in the face of his pursuer, and escapes under cover of the cloud; this is the substance used by painters, and called sepia, whence the generic name of the mollusks which produce it.

In the British seas none of these cephalopods attain so large a size as to be formidable to man, as they do in warmer climates. It was asserted by Dens, an old navigator, that in the African seas, while three of his men were employed during a calm in scraping the sides of the vessel, they were attacked by a monstrous Cuttle-fish, which seized them in its arms, and drew two of them under water, the third man was with difficulty rescued by cutting off one of the creature’s limbs, which was as thick at the base as the fore-yard of the ship, and had suckers as large as ladles; the rescued sailor was so horrified by the monster, that he died delirious a few hours after. An account is also given of another crew who were similarly attacked off the coast of Angola; the creature threw its arms across the vessel, and had nearly succeeded in dragging it down, and was only prevented doing so by the severing of its limbs with swords and hatchets. A diligent observer of nature has asserted that in the Indian seas Cuttle-fish are often seen two fathoms broad across the centre, with arms nine fathoms long. Only think, what a monster! with a body twelve feet across, and eight or ten legs like water-snakes, some six and thirty feet long. Well may it be said, that the Indians when they go out in boats are in dread of such, and never sail without an axe for their protection.

There is a story told by a gentleman named Beale, who, while searching for shells upon the rocks of the Bonin Islands, encountered a species of Cuttle-fish called by the whalers “the Rock-squid,” and rashly endeavoured to secure it. This cephalopod, whose body was not bigger than a large clenched hand, had tentacles at least four feet across, and having its retreat to the sea cut off by Mr. Beale, twined its limbs around that gentleman’s arm, which was bared to the shoulder for the purpose of thrusting into holes of the rocks after shells, and endeavoured to get its horny beak in a position for biting. The narrator describes the sickening sensation of horror which chilled his very blood, as he felt the creature’s cold slimy grasp, and saw its large staring eyes fixed on him, and the beak opening and closing. He called loudly for help, and was soon joined by his companion, who relieved him by destroying the Cuttle-fish with a knife, and detaching the limbs piece by piece.

There are several species of these cephalopods; the most generally distributed appears to be the Octopus vulgaris, or Common Cuttle-fish, which is sometimes found on our own shores, where also may be obtained the Common Sepiola, S. vulgaris, usually about three inches long, and the Officinal Cuttle-fish, S. Officinalis, which is about a foot in length; we give below small figures of each of these three species, to show the difference in the shape: the two last, it will be observed, have, in addition to the eight tentacles, which give the generic name Octopus, signifying eight, two long side arms, the use of which does not appear to be very clearly determined.

NAUTILUS AND AMMONITE.

The Nautili are called testaceous cephalopods, our readers know, or ought to know, the meaning of both these terms. Like the Cuttle-fish they are sometimes called Polypi, because they have many arms or tentacles, the word poly, with which a great number of English words commence, being the Greek for many. An ancient writer named Aristotle, after describing the naked cephalopods, says, “There are also two polypi in shells; one is called by some, nautilus, and by others, nauticus. It is like the polypus, but its shell resembles a hollow comb or pecten, and is not attached. This polypus ordinarily feeds near the sea-shore; sometimes it is thrown by the waves on the dry land, and the shell falling from it, is caught, and there dies. The other is in a shell like a snail, and this does not go out of its shell, but remains in it like a snail, and sometimes stretches forth its cirrhi.” The first of these animals, there can be no doubt, is the Argonaut, or Paper Nautilus, and the latter that which is called the True Nautilus, of both of which species let us say a few words, which we will introduce by quoting some beautiful lines from a poem called “the Pelican Island,” by James Montgomery.

The tiny mariner here alluded to, is the Paper Nautilus, common in the Mediterranean and some tropical seas; its scientific name is Argonauta argo. In the mythology, we read that Argo was the name of a ship that carried a certain Grecian named Jason, and a crew of argives in search of adventures; some say that the term is derived from a Greek word signifying swift: this party of mariners, said to be the first that ever sailed upon the sea, was called Argonauts, or, as it might be freely translated, seamen of the ship Argo. Nauticus, in Latin, signifies anything relating to ships or navigation, and here you have the whole origin of the name of this little Argonaut, about which we must sing you a song written by Mary Howitt, before we proceed further:—

Many more poems of the like nature we might quote, for this little shelled cephalopod has been a favourite with the poets time out of mind, and in some instances they and the less imaginative naturalists have disagreed in their accounts of its form and operations, for instance, Pope says—

“Catch a fiddle-stick,” say some naturalists, the little Nautilus does nothing of the sort; and if you go to him to learn navigation, you will never be much of a sailor; he may teach you how to sink to the bottom and rise again, and that kind of knowledge might be worth something to you if you could breathe under water; and he might teach you how to swim, but not how to sail, for in spite of all poetic theories, he does the former and not the latter. Most usually he walks about at the bottom of the sea on his long arms, something like the Cuttle-fish, feeding on the marine vegetation; the shell is then uppermost; if we could look inside of it we should see numerous little chambers or cells, the larger and outermost of which only are inhabited by the mollusk, the others being filled with air render the whole light and buoyant. Through the centre of these chambers, down to the smallest of them, runs a membranous tube which can be exhausted or filled with fluid at the pleasure of the animal, and the difference thus effected in the weight of the shell enables it to sink or swim; in the latter case, up it goes to the surface, and “keel upwards from the deep,” emerges, as the poet has said, but once there it soon reverses its position. The shell becomes like a boat it is true, but its inhabitant neither points a sail nor plies the oar, but propels itself along stem foremost by a muscular action, which by alternately compressing and loosening a kind of siphon, throws out jets or gushes of water, which by the resistance they meet with from the surrounding fluid, give the desired onward motion, and away the swimmer goes, his long arms gathered closely together, and streaming behind like the tail of a comet, and its round eyes keeping a sharp look-out on either side. Should it espy danger, the body and limbs are withdrawn into the shell, and the fluid driven through the central tube, so as to compress the air in the pearly cells, and down sinks the swimmer once again to his native depths, where

We give below two figures of the Argonaut, one of which represents him crawling at the bottom of the sea, and the other swimming on the surface.

The True, or Pearly Nautilus, (N. Pompilius,) the origin of whose specific name we have been unable to discover, is much like the Argonaut in appearance and general construction; the shell is externally smoother and more iridescent, it is also generally somewhat thicker than the former kind, and has internally more chambers or divisions; its pearly lustre renders it a beautiful ornament, and the large size it frequently attains a very conspicuous one. Its inhabitant has several peculiarities of organization, which distinguish it from the Argonauts, but into these we need not enter; neither can we pause to describe the other species of nautili, the shells of which, like those of the Cowry and other univalves, are covered with a membrane which hides their beauty. This membrane or mantle sometimes extends some distance beyond the edge of the shell, and, being of a light and filmy appearance, may have been mistaken for a sail hoisted by the creature to catch the breeze, while its long arms, thrust up into the air or down into the water, may have been thought to be masts or oars, so that the poets are not so much to be blamed, if they say as Wordsworth does.

Nearly allied to the Nautili are these beautiful fossil shells called Ammonites, from their fancied resemblance to the horns of a heathen deity or god, called Jupiter Ammon. These shells, at once the wonder and pride of geologists, are found in the chalk formations, and thousands of years must have passed away since they were inhabited by living creatures. The Nautili which swam and sported with them at the depths of the ocean, as is proved by the shells of many species found in the same chalky deposits, have still their living representatives, but those winding galleries and pearly chambers once fragile as paper and brittle as glass, now turned into, and surrounded by solid stone, are all shells of extinct species, and we can hardly see and handle them without some degree of awe and reverence; when we reflect on the great and wonderful changes that have passed over the earth since they were formed by a hand divine, instinct with the breath of life, and then to be embedded in the rock as everlasting characters by which the unborn generations of men might read in history of those changes, and of the providential dealings of God with his creatures. Of these Ammonites, and other fossil shells, much more will have to be said in our proposed geological volume; the poem which follows will very appropriately conclude the above remarks, and our present little work on shells—beautiful, wonderful shells! useful, ornamental, instructive! The subject is one which we would earnestly invite our young readers to study: it is but here introduced; we have picked up a few, very few, of the wonders and beauties of conchology, and presented them to their notice in the hope that they may be induced to desire a more intimate acquaintance with this branch of natural science, which has been hitherto greatly neglected. To understand it thoroughly, much attention and perseverance will be required, but even a slight acquaintance with it will yield both pleasure and profit to the mind.

THE NAUTILUS AND THE AMMONITE.