Part 7

We will now go to Fig. 3, the Spined Cytherea, the Cytherea or Venus Dione of naturalists; the meaning of the term is the mother of Venus, who was, as you will remember, the goddess of beauty, given to this shell perhaps because it is entitled to occupy a place at the head of the Cytherea, a genus of the Cardiidæ, or Cockle family, of which genus there are about seventy-eight living species; this, as it is the most rare, is also, perhaps, the most beautiful; it is found in the seas of America, and is remarkable for the row of spines on the hinder border of each valve; these vary much in size and number, being in some individuals long and far apart, in others, short, thick, and closely set. The colour of the shell also varies considerably, being sometimes of a delicate rose colour; at others, more of a claret; at others again, bordering on purple. It was for one of the first discovered specimens of this shell, that £1000 is said to have been given. Truly a Venus of value this; it ought to be called the Queen of Cockles!

Our next example, (see Fig. 4,) is the Spotted Tridacna, (T. maculatus,) the latter term signifying spotted. In the Chamidæ or Clam family, is placed the Tridacna genus, the discovered species of which are not numerous; they are chiefly found in the Indian seas. The one above mentioned claims pre-eminence for beauty. We cannot quite see the applicability of the generic name; Tridacnus, in Latin, signifies to be eaten at three bites, but he must be a man of large capacity indeed who could so devour the head of this family, the Giant Tradacna, (T. gigas,) a single specimen of which has been known to weigh as much as five hundred and seventy pounds; from three to four hundred is by no means an uncommon size. The shell of this giant mollusk is of a very picturesque shape, something like its spotted congener, as we call anything of the same kind or genus, only it is somewhat plainer, and more deeply ribbed and indented. The inside is of a glossy whiteness, and it is frequently used as a basin for garden fountains, or the reception of rills or little jets of water, which sparkle in its stainless hollow. In the church of St. Salpice, at Paris, is a shell of this immense Clam, the valves of which are used as receptacles for holy water; it was presented to Francis the First, by the republic of Venice. Fancy the clapping to of such a pair of valves, when the animal closes its shell in alarm, and the strength of the cable required to moor it to the rocks or coral reef. The spotted species here figured has a solid and heavy shell, very elegantly shaped, and beautifully marked, as will be seen; the greatly reduced size of the figure prevents anything like justice being done to the original.

The above is a figure of the Heart Isocardea, (I. cor,) which is also a member of the Clam family, and one of the most elegantly-shaped shells in the whole range of Conchology. It is a native of the Mediterranean and other seas of Europe, and has been taken in deep water on the West coast of Ireland. We complete this group with a representation of the curious Arcadæ family, or Ark shells, as they are commonly called, because one of the species was thought to resemble the ark built by Noah. Mr. Swainson tells us that the animals of these shells affix themselves to other bodies by a particular muscle, which is protruded through the gaping part of the valves; they also adhere, when young, by means of the bissiform epidermis, or bissus-like outer skin: this species is a native of the Atlantic Ocean and the seas of Europe. The Antique Ark, (A. antiqua,) is very like the Common Cockle, being of a white colour, and heart-shaped. We give below a representation of this shell, and also of the shell of the pretty little Pearly Trigonia, (T. margaritacea,) included in the Arcadæ family; this is a rare species, found only in the seas of New Holland.

SCALLOP SHELLS.

Several species of Scallop Shells are found scattered about on our shores; they belong, as before stated, to the family Pectinidæ, the meaning of which term has been already explained. These shells were called by Cuvier “the Butterflies of the Ocean,” on account of the various and beautiful colours which they exhibit. Some of them are exceedingly thin, and brittle as glass; one species found in the Arctic regions, is as transparent as that substance, and is therefore called P. vitreus, from the Latin for glass, which is vitreum. One of the commonest of our native Scallops is the St. James’ Cockle, (P. Jacobœus;) this shell is found in great plenty along our southern coasts; it is often referred to by old writers, on account of having been commonly worn in the hats of pilgrims to Palestine, or the Holy Land, as the scene of our Saviour’s life and death was called. Sir Walter Raleigh, in his poem called “The Pilgrimage,” thus enumerates the different articles considered necessary for a Palmer, as these pilgrims were termed:—

“Give me my scallop shell of quiet, My staff of faith to lean upon, My scrip of joy, (immortal diet,) My bottle of salvation, My gown of glory, hope’s true gage, And thus I’ll make my pilgrimage.”

This Mollusk, it may be noticed, like many other bivalves, has a flat, and a concave or hollow shell: in early times when plates and drinking vessels were not so plentiful as they are now, one of these served the former purpose, and the other the latter; thus, in speaking of a feast, a Gaelic or Scottish bard has said—

“The joy of the shell went round.”

Sometimes the species termed Pecten opercularis, was used as the pilgrim’s badge; the specific name comes most likely from the Latin operculum, whose meaning has been explained.

This too, is a common British shell, as is also the little speckled Scallop, (P. varia,) which may be found on almost any part of the coast where the water-line is margined with a sandy ridge. The shells are generally about two inches long, of various colours, clouded, speckled, and marked with about twelve ribs. There is a foreign species called the Flounder Scallop, P. pleuronectes, which is remarkable for having the two valves of the shell of different colours, the upper one being of a rich reddish brown, and the lower one white: the specific name has reference to this, being compounded of the Latin pleura—something double, and necto—to join. The fish called the Flounder, is brown above and white beneath, hence the English name of this shell. The preceding engraving of the Common Scallop, viewed from the front, shows the flat and concave form of the two valves of this shell, and also the depth of the indentations or ridges.

LIMPITS.

Among the rocks of the British coast, there are no shells more frequently met with than those of the Common Limpit, Patella vulgata; they lie scattered about like so many little empty cups, each having, on the death of the mollusk, fallen from the rocky cavity in which it was embedded, and which was just large enough to contain it. Here the animal attaches itself so firmly by its fibrous foot, which is hollow in the centre, and acts like a sucker, that it is almost impossible to loosen its hold otherwise than by inserting something thin, like the blade of a knife between it and the stone. By this power of adhesion, the Limpit is protected from the violence of the waves, and also from its numerous enemies, aquatic birds and animals, which have a relish for its flesh. Still vast numbers are used as food, both by man and the inferior creatures, so that the means of defence furnished to the Limpits of the rock, are not always sure. “The peasantry of the western isles of Scotland,” we are told by Miss Pratt, “look to the Periwinkles and Limpits, which abound on the rocks, for their daily meal, often for long seasons, subsisting almost entirely upon this humble food. In the Isle of Skye, the inhabitants are often, at one time of the year, without any other source of provision.” Then comes the Sea-gull, and the Duck, and the Pied Oyster-catcher, to feed on the poor little mollusk, the bill of the latter bird being admirably adapted for loosening its hold on the rock.

Patella in Latin signifies a salad-dish, a knee-pan, and several other domestic utensils, of a broad shallow make, and hence we find the plural form of the word applied to the Limpit family, whose shells are of such a shape. Members of this family are found on all rocky coasts, except those of the Arctic seas; on Tropical rocks they grow to a large size, and form a valuable article of food. A very curious piece of mechanism is the tongue of the Common Limpit, it is from two to three inches long, and has a spoon-like extremity, so that it looks, when extended from the mouth, like a small snake; if examined through a microscope, it is seen to be armed throughout its whole extent with rows, four deep, of sharp hooked teeth, and between each row are placed two others, which have three points, and are set in a slanting position; the use of this arrangement we cannot at present determine, but no doubt it has a perfect adaptation to the wants of the animal.

There are shell-fish called Key-hole Limpits, which belong to the genus Fissurellidæ, from fissura—a cleft or slip, from whence comes also fissure. All the members of this genus are distinguished by the aperture at the top of the shell, shaped like a key-hole, which is situated exactly over the breathing organs, and serves as a channel for the water necessary for respiration.

Frequently upon the fronds of the large olive sea-weeds may be found a tiny shell shaped something like that of the Common Limpit; it is of an olive green colour, with blue streaks, and is called, from its clearness, the Pellucid Limpit, P. pellucida. There is also another much like it in appearance, which naturalists call P. lœvis. To the labours of these little mollusks, according to Dr. Harvey, may be partly attributed the destruction of the gigantic Algæ, (sea-weed.) Eating into the lower part of the stems, and destroying the branches of the roots, they so far weaken the base, that it becomes unable to support the weight of the frond; and thus the plant is detached and driven on shore by the waves.

“And so the forest tall that groweth, Underneath the waters clear, Does the little woodman mollusk, Level every year; From small causes, great results— Teaching you to persevere.”

ROCK-BORERS.

The family Pholadæ comprises a group of mollusks, the boring habits of which have long been known; they penetrate wood, hard clay, chalk, and rocks, and devastate the labours of man; they attack the hulls of ships, the piles which form the foundations of piers and break-waters, and they force themselves upon our attention by the loss of property, as well as of life, which results from their hidden depredations. Of this family, those belonging to the genus Pholus may be more especially likened to the Edomites of Scripture, because they take up their abode in the rock, and hollow out for themselves dwellings therein. With a shell as thin as paper, and brittle as glass, the wonder is how these Rock-borers work their way into and through hard stones. Some naturalists assert that they effect this by means of an acid which decomposes the substance of the rock, and renders it soft; others, that the animal keeps turning round and round like an instrument called an auger, and so gradually rasps away the surface of the stone with the angles of its shell, but we question whether the shell would not be worn out first in such a process. The generic name of these “stone-piercers,” comes from the Greek word Pholeo—to hide, and the rocky chambers which they hollow out for themselves, are as snug hiding-places as can well be imagined; yet, however deep they may go into these gloomy caverns, as we should be apt to suppose them, they need not be in darkness, for it appears that these Pholades emit a most remarkable light, whether phosphorescent or not does not appear to be determined; so strong is it, that it is said to illuminate the mouth of the person who eats the mollusk; and it is remarked by Dr. Priestly, that “contrary to the nature of most fish, which give light when they tend to putrescence, this is more luminous the fresher it is, and when dried its light will revive on being moistened with water.” So that in more respects than one these rock-borers are mysteries. The most common of them, perhaps, is the Prickly Pidduck, or Peckstone, (P. dactylus,) which is much used by the fishermen of our coasts as bait; the specific name is the Latin for a fruit shaped like a finger, which is something like the shape of this mollusk, as will be seen by the annexed engraving.

The genus Pholus is very widely distributed, and all the species have the same boring habits as those of our own coast, which we need not enumerate. Like them too in this respect are the marine worms called Teredo, which make their way into the bottoms of ships, and all submerged timber, but these will be more fully spoken of in another volume. The above figure exhibits the Pholas dactylus as it appears in a section of rock, split open for the purpose of seeing the shelly miner at his work.

MULTIVALVES.

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:—