Part 3
If we take a Common Snail, and plunge it into boiling water, which will instantly kill it, so that it can be removed from the shell, we shall find the whole of that part of the body which was lodged in the upper whorls, or spiral part of the shell, is covered with a thin membrane or skin; this is called the _mantle_, and that portion of it which corresponds with what we may consider as the back of the mollusk, and which is considerably thickened, is termed the _collar_; here are situated the glands, which secrete the colouring and other matter of which the shell is mainly composed; although the substance called nacre, or mother-of-pearl, is secreted in the thinner part of the mantle; it is however from the collar that the growth or increase of the shell proceeds. It is in accordance with certain variations in the shape and disposition of this mantle and collar, that shells assume such very different shapes. Sometimes the whorls or spiral ridges, are projected or thrown far out, and this produces the _turbinated_ shell. Sometimes they scarcely rise above each other, but rather spread towards the sides, and then we have the _discoid_ shape. Generally speaking, the whorls of a shell take a direction from left to right, but occasionally an opposite one; they are then called sinistral, or left-handed shells: such are not common. If one of the twisted shells be divided length-ways, it will be seen that the inside of the whorls wind in an ascending direction, round the _Columella_, or central column, as the spiral staircases in the Crystal Palace.
But let us return to our Garden Snail, who has many near relatives in Britain, several of which have beautifully-marked and convoluted shells, as will be seen by a reference to our coloured illustrations, Plate I. We will introduce them in due order. Fig. 1, the Banded Snail, (_Helix nemoralis_,) from the Latin _nemus_—a wood or grove; the prettily-striped shells of this species may be found in great plenty among the roots and in the crevices of the rugged boles of old forest trees, as well as in hedge-rows and in mossy banks, and other situations near woods. Fig. 2, the Heath Snail, (_H. ericetorum_,) from _erica_, the Latin for heath; a small species with brown bands, remarkable for its large _umbilicus_, perforating the centre of the shell nearly through. Fig. 3, the Silky Snail, (_H. sericea_,) from the Latin _sericus_—silk-like; the shell of this species is covered with short slimy hairs, which give it a glistening appearance. Fig. 4, the Stone Snail, (_H. lapicida_,) from the Latin _lapis_—a stone: Linnæus called the species the Stone Cutter, probably on account of its habit of frequenting stony places, and the peculiar construction of the shell, which has a sharp edge running round each whorl; it is commonly found lodged in the cavities of loose-lying stones, but which it can scarcely be suspected of having hollowed out for its own accommodation.
Fig. 5, the Elegant Cyclostome, (_Cyclostoma elegans_.) On turning to the dictionary, we find that _cyclostomous_ means having a circular mouth. This species is sometimes called _Turbo elegans_; the beautifully-marked shells are often found in chalk-hills covered with brushwood. This pretty mollusk has a curious mode of travelling; the under surface of the foot, which is long, is divided by a deep fissure, into two narrow strips, like ribbons; these take hold of whatever the creature may be moving on alternately; one keeping fast hold while the other advances, in like manner to fix itself, and drag the body forward. Fig. 6, the Undulated Plekocheilos, (_P. undulatus_;) the Latin _plecto_—to twist or twine, seems to be the root from which the generic name of this Snail is derived; the specific name will be easily understood; to undulate, is to flow like waves, and the lines on the shell it will be seen are undulating. This is not a British species, but is introduced here to give variety to the group; it is a West Indian Mollusk, and is found in immense numbers in the forests of St. Vincent; it glues its eggs to the leaves of a plant which holds water, and thus secures for them a damp atmosphere at all times. And here we must conclude our chapter of Land Snails, leaving unnoticed very many beautiful and interesting species, both British and Foreign.
Many poets have alluded to the Snail, but we can only find room for a few verses by Cowper:—
To grass, or leaf, or fruit, or wall, The snail sticks close, nor fears to fall, As if he grew there, house and all Together.
Within that house secure he hides, When danger imminent betides Of storm, or other harm besides, Of weather.
Give but his horns the slightest touch, His self-collecting power is such, He shrinks into his house with much Displeasure.
Where’er he dwells, he dwells alone, Except himself has chattels none, Well satisfied to be his own Whole treasure.
Thus hermit-like, his life he leads, Nor partner of his banquet needs, And if he meets one only feeds The faster.
Who seeks him must be worse than blind, (He and his house are so combin’d,) If, finding it, he fails to find Its master.
FRESH-WATER SHELLS.
Many of the following group of Fresh-water Shells, are remarkable for elegance of form, and some for richness of colouring; hence, perhaps, the scientific name applied to the family in which they are mostly included—_Limnæidæ_, which, like _limn_—to paint, agrees with the French _enluminer_. These mollusks are found in rivers, streams, ditches, and moist marshy places. Like those which live wholly on land, they breathe through lungs, and therefore cannot exist without air; which accounts for their frequently coming to the surface, when under water. In brooks, as well as in stagnant pools, which abound with aquatic plants, they may be found in vast numbers, feeding upon the moist vegetation.
[Illustration]
The Common Limnea, (_L. stagnalis_,) is mostly an inhabitant of stagnant waters, where it is often seen floating with the shell reversed, as in a boat; this shell, like most of those of the Fresh-water Mollusks, is thin, and easily broken; the shape it will be seen, is peculiarly elegant, the spire being slender and pointed—very different from that of the Spreading Limnea, called by naturalists, _L. auricularia_, from _aurus_—the ear, to which the broad aperture, or opening of the shell, may be compared; this resembles the other species in its habits. The Horny Planorbis, in Latin _P. corneus_, from _cornu_—a horn. The shape, you will see, is flat, the whorls rolling upon each other like the folds of a bugle horn; this shape would be termed orbicular, from _orbis_—a sphere, or circular body. This is the largest European species of Fresh-water Shells so constructed; it is often found in deep clear ditches, and yields a beautiful purple dye, which, however, soon becomes dull, and changes; it cannot be fixed, and is therefore valueless. The mouth of this shell in fine specimens, is tinged with pale violet or lilac.
[Illustration]
There is another kind, the Keeled Planorbis, (_P. lurinatus_,) which has the outer edge of the shell finely ridged, or keeled; it is very small, and very plentiful in fresh-water, both running and stagnant; where, too, is found the Common Physa, (_P. fontinalis_,) the latter word meaning a spring or fountain. This little mollusk is a quick and active traveller, it sometimes comes out of its shell, and throws itself about in an extraordinary way, keeping fast hold by its foot; the generic name, _Physa_, would seem to have reference to the round, smooth, delicate shell, and to come from the same root as _Physalite_, which means a topaz: the members of this genus are very numerous, being found nearly all over the globe. The next belongs to the family _Auriculadæ_, or Ear Shells. The Midas’ Ear, (_A. Midæ_;) this handsome shell is prized by collectors; it comes from the East Indies. Midas, it is said, was one who set himself up for a judge of music in the old fabulous times, and not appreciating that of Apollo, was rewarded by the angry god with a pair of ass’s ears.
[Illustration]
The Cone-shaped Melampus, (_M. corniformis_,) also an Ear Shell, is found in the rivers of the Antilles Islands. It is a pretty shell; the formation is much the same as that of many of the most highly-prized varieties of Marine Shells; of these we shall have to speak presently. _Melampodium_ in Latin, signifies a poisonous plant called Black Helebore; in the Mythology, _Melampus_ was a great magician, who did all sorts of wonderful things; but we cannot tell what relation there exists between either the plant or the magician and this pretty cone shell. To give variety to this group, we will now throw in a land species called _Megaspira Ruschenbergiana_, about the origin of whose name we cannot even hazard a guess; the termination of the generic name, you will see is _spira_, and a glance at the shell will at once suggest a reason for this; its long tapering spire consists of twenty-three closely-set gradually increasing whorls. This is a rare shell, whose inhabitant has not yet been described by naturalists; several of the marine species closely resemble it in shape. Much more might be said about the Land and Fresh-water Shells, but we must here leave them, having a wide field before us, namely, the Sea or Marine _Testacea_, one of the most common of which is
[Illustration]
THE WHELK,
A univalve shell inhabited by a gasteropod mollusk, or, we should rather say, naturally so tenanted, for very frequently it is taken possession of by the Soldier or Hermit Crab, which having no hard covering to protect their soft plump bodies, are obliged to take lodgings where they can get them, and generally prefer the Whelk shell, of which we here give a figure.
[Illustration]
This is one of the commonest of our Marine Mollusks; it is called by naturalists _Buccinum undatum_; the first, or generic term, being the Latin for a trumpet, and the second, or specific name, meaning waved, or, as we often say, undulated. So we call this the Waved Whelk; fishermen term it the Conch, or the Buckie, and tell strange stories of its ravenous appetite and murderous propensities; how, with its spiny tongue, situated at the end of a long flexible proboscis or trunk, it drills a hole in the shell of the Oyster, or other testacean, and sucks out the contents; empty shells, so drilled, are frequently found on the shore, and often, when the dredge is let down into an oyster bed, it comes up time after time filled with Whelks, of which such numbers are sometimes taken, that they are sold to the farmers to be used as manure for the soil. This mollusk is a favourite article of food with the poorer classes of our land, but it is hard and indigestible. The shell may frequently be found in large numbers among the beach stones; it is strong and firm, from three to four inches long, of a dirty yellowish white. There are two other Whelks common upon our coasts—the Stone or Dog Whelk, (_B. lapillus_,) from the Latin _lapis_—a stone, and _B. reticulatum_, so called because the shell is _reticulated_, or marked with many lines crossing each other, like net-work; it comes from the Latin _reticulum_—a net; hence also we have _reticule_—a small work bag, at one time very much carried by ladies.
ROCK SHELLS,
Are so called on account of their rough and wrinkled forms; they are nearly allied to the Whelks, to which they bear a close resemblance. Several species are found on our shores, the most common being the Humble Murex, (_M. despectus_,) from the Latin _despecto_—to despise; this is often used by the fishermen for bait. Some of the foreign Rock Shells are very curious and beautiful; three of them will be found on Plate II.—Figs. 1, 2, and 3. The Common Thorny Woodcock, (_M. tribulus_,) from the French for trouble, whence we have also tribulation, which is sometimes said to be a thorny path. This curious shell is also called Venus’ Comb. It is found in the Indian Ocean, from whence it is also brought. Fig. 2, the Woodcock’s Head, (_M. haustellum_,) from the Latin _haustus_—a draught; the bill of the Woodcock being adapted for sucking. This term is also applied to insects that live by suction. The shell, it will be seen, is destitute of spines, but it is ribbed and beautifully marked. Fig. 3 is worthy of its name—the Royal Murex, (_M. regius_,) from _regno_—to reign. It is a splendid species, of the rich colouring of which, art can give but a faint impression. It is brought from the western coast of Central and South America, where, as well as in the islands of the South Pacific, many new shells of the genus _Murex_ have been discovered.
[Illustration]
One shell found on our own coast, often mistaken for a Whelk, is the Pelican’s-foot Strombus, called in scientific language, _Strombus pes-pelicanus_, which is but a Latinized form of the English name. This shell varies greatly in shape in different stages of its growth, and by an inexperienced conchologist, the young, middle-aged, and old Strombus, might be taken for distinct species. In the _Strombidæ_ family, so called we know not why, the same word in Latin meaning a kind of shell-fish, are some species which have produced pearls. One member of the family which we sometimes see in collections, is a large and very beautiful shell; this is the Broad-winged Strombus, (_S. latissimus_,) probably from _latesco_—to wax or grow broad, or large; _issimus_ being in the superlative degree, would indicate that this shell was very much so, as we find it is, sometimes measuring as much as twelve inches across. In Plate II, is a representation of this handsome shell, greatly reduced in size, of course: see Fig. 4. We here give a figure, as more curious than beautiful, of the Scorpion Pteroceras, (_P. scorpius_,) which also belongs to the _Strombidæ_ family; as does the curious Chinese Spindle, (_Rostellaria rectirostris_.) The generic name of the first of these species, comes from the Greek _Ptero_, pronounced _tero_, meaning a wing, and _cerus_—waxen. Both the generic and specific names of the second refer to the peculiar conformation of the shell, being derived from the Latin, and meaning a straight line or beak.
[Illustration: CHINESE SPINDLE.]
On Plate III, will be found the Imbricated Purpurea, (_P. imbricata_,) Fig. 1, which claims a close alliance with the Whelks. The generic name has reference to the dye yielded by this, as well as all the shells of the genus; the specific name comes from the Latin _imbrex_—the gutter-tile; thus _imbricated_, a term often used in Natural History, means ridged, like the roof of a house, where the tiles are placed to overlap each other, so that the rain will run off. The Persian Purpura, or, as it is called in Latin, _Purpura Persica_, Fig. 2, is another handsome shell of this family group; its name indicates the place where it is found. The other species described comes from South America, and the _P. lapillus_, (the meaning of the specific name has already been explained,) is common on our shores, being found in great abundance on the rocks at low waiter. We read in scripture, of Tyrian purple, and there is every reason to suppose that the rich colour was obtained from these and other shell-fish.
PERIWINKLE.
[Illustration]
This is the commonest representative which we have of the family _Turbinidæ_, which comprehends, according to Cuvier, all the species which have the shell completely and regularly _turbinated_, that is, if we translate the Latin word into English, twisted. The little Periwinkle, (here he is,) is by no means a handsome mollusk, but some of his relatives are very beautiful as we shall presently show. He is called by naturalists _T. littoreus_, from _littoralis_—belonging to the shore, and often eaten by boys and girls with great relish; but he is not very digestible, and sometimes occasions dangerous disorders. The Swedish peasants believe that when the Periwinkle crawls high upon the rocks, a storm is brewing from the south; but Linnæus quotes a Norwegian author to shew that according to popular belief, it foretells the approach of a land wind with a calm on shore. Man may learn much of elemental changes from an observation of the movements and habits of all living creatures, which are instructed by God to provide for their safety and wants, and often perceive, long before man himself does, the indications of calm and tempest, rain and drought, etc. But our little _Turbo_, what of him? will you boil him, and pick out his curled-up form with a pin? or let him go crawling about the rocks, feeding upon the delicate earlier growth of marine vegetation? In the former case, you will have to reject the little kind of horny scale attached to his foot, which forms, when he retires into his habitation, a closely-fitting door to make all snug.
Several species of this genus are found on our shores; one of those is the _Turbo rudis_, or Red Turbo, which has a very thick periwinkle-like shell, about three-quarters of an inch long; the colour is dull red, fawn, or drab.
Of the foreign _Turbinæ_, sometimes called Turban Shells, we will now introduce two or three species, which will be found on Plate III. Fig. 3 is the Marbled Turbo, (_T. marmoratus_,) from the Latin _marmor_—marble; a large handsome shell well known to conchologists, and a native of the Indian seas. Fig. 4 is the Twisted Turbo, (_T. torquatus_;) this shell, when deprived of its outer coat or layer, is beautifully _nacreous_, or if we may so speak, mother-of-pearly. The specimens which have reached England were brought from King George’s Sound. Fig. 5 is called Cook’s Turbo, (_T. Cookii_:) this is a handsome South Sea shell, oftentimes of large size. It has been found in great numbers on the coast of New Zealand.
On Plate IV, we have placed two very curiously formed and marked shells, called Wentletraps, also belonging to the family _Turbinidæ_. The scientific name is _Scalaria_, from the Latin _scala_—a ladder, which the ribbed shells are supposed to resemble. Of this genus there are about eighty distinct species known; they are mostly deep-sea shells found in warm latitudes, although several inhabit the European seas, and one, the Common False Wentletrap, (_S. communis_,) Fig. 1, may often be picked up on our own shores. Fig. 2, the Royal Staircase Wentletrap, is a rare and valuable shell, generally brought from India and China; the scientific name is _S. pretiosa_, given to it by the French Naturalist Lamarck, on account of the high price which it fetched, _pretiose_, in Latin, meaning costly, valuable. As much as £100 have been given for a single specimen of this shell; and a fine one, especially if it exceed two inches in length, yet commands a considerable sum, although not nearly so much as that. A good deal like the False Wentletrap in general outline, is the Awl-shaped Turritella, found in the African and Indian Seas. This is the _T. terebra_ of naturalists; the first name referring to the turret shape common to the genus, and the last being the Latin word for an auger, or piercer. The Roseate Turritella, (_T. rosea_,) is also sometimes seen in collections; the beautiful rosy tint of the live shell changes to a dull red or brown, on the death of the mollusk.
TROCHUS, OR TOP-SHELL.
“Of the shelled Mollusca which the dredge ever and anon brings up,” says Mr. Gosse, in his delightful volume on the _Aquarium_, or _Aqua-vivarium_, as the glass tank in which living marine animals and vegetables are kept, is called, from the Latin _aqua_—water, and _vivo_—to live, “the _Trochi_ are among the most conspicuous for beauty. The chief glory of this genus is the richly-painted internal surface of their shells, in which they are not excelled by any even of the true margaritiferous or pearly bivalves.”
Of this _Trochidæ_ family, a few of the members must be introduced to our readers; it is rather a numerous one, consisting of more than one hundred species, which are scattered nearly all over the world, few seas being without some of them. They are found at various depths, from near the surface to forty-five fathoms down, creeping on rocks, sand, masses of sea-weed, etc. We will first speak of those found on our own shores, the two commonest, as well as the smallest of which, are the Grey and the Spotted Trochi, scientifically named _T. cinerarius_ and _T. maculata_, the translation of the first Latin specific name being ashy or ash-coloured, and that of the second, spotted. _Trochus_, in the same language signifies a top, and has reference to the shape of most of these shells, which are something like a boy’s whip-top.
Children on the coast sometimes call the last-named of the above species Pepper-and-salt Shells, because in colour they resemble the cloth so named. The Muddy-red Trochus, (_T. ziziphinus_,) so called, perhaps, because in colour it resembles the ziziphia, or fruit of the jujube tree, is also common with us. This shell is about an inch long, of a grey tint dashed with dark spots, these follow the line of the spiral turnings, which are very regular, proceeding from the opening below to the apex or point. Seen on shore, its colours are dull and faint, but beneath the water, inhabited by a living mollusk, it looks as though made of pearl, and studded with rubies; the animal, too, is richly coloured, being yellow with black stripes.—See Plate IV, Fig. 3.
Not so common as the last is another British mollusk of this genus, called the Granulated Trochus, (_T. granulatus_.) It is the larger, and, as many think, the more elegant shell of the two, being in colour, a faint flesh tint or yellowish white, shaded here and there with purple; the spiral lines which encircle it are composed of small round knobs which stand out like beads.
There is a singular shell of this genus, called the Carrier Trochus, (_T. phorus_;) it is generally found loaded with foreign objects, such as shells, small stones, bits of coral, etc., which it attaches to itself, and so goes about like a collector of natural curiosities, with his cabinet on his back.
The Imperial Trochus, (_T. imperialis_,) Fig. 4, whose scientific name explains itself, is one of the handsomest shells of the genus; it is very rare, and has hitherto been found only at New Zealand. Let us give our young readers a specimen of the way in which scientific writers describe shells; thus, this foreign Trochus, they tell us is “orbicularly conical, the apex obtuse, the whorls turgidly convex, squamoso radiate at the margin.” This is quite a simple affair to some descriptions, and simple in fact it is to one, who, by attentive study, has become familiarized with the meaning of the terms. To one also who is acquainted with the Greek and Latin tongues, they will be sufficiently plain, although he has never seen them applied before, for they are all derived from those dead languages, as they are called, and so convey their own meaning to every educated naturalist, no matter of what nation he may be; and hence their chief value. It is not necessary for our readers to trouble themselves about the meaning of such terms at present; by and by it will be necessary for them to do so, if they wish to prosecute the study of any natural science.