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The Ocean World: Being a Description of the Sea and Its Living Inhabitants. cover

The Ocean World: Being a Description of the Sea and Its Living Inhabitants.

Chapter 16: CHAPTER XII.
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About This Book

This work provides a popular natural-history survey of the sea's physical features—depth, colour, salinity, currents, tides, and phosphorescence—and a richly illustrated, systematic account of marine life. It progresses from microscopic organisms and zoophytes through corals, jellyfishes, echinoderms, and molluscs to crustaceans and fishes, describing form, metamorphoses, behaviour, and ecological interactions. Chapters treat anatomy, reproduction, feeding, and human practices such as fishing and collection, while vivid descriptions of reef and polar environments convey diversity across habitats for a general readership.

Fig. 132. Pholas crispata (Linnæus).

The perforations produced in stone by the Pholades have become important evidence in a geological sense. In many countries there were evident signs of a considerable sinking of the earth. But in no place is the evidence of this so clear as in the monument of high antiquity on the Pozzuolan coast, known as the Temple of Serapis.

Fig. 133. Pholas papyracea (Solander).

Fig. 134. Pholas melanoura (Sowerby).

In speaking of the culture of oysters by the Romans, we shall have occasion to mention the disappearance of the Lucrin Lake, and its replacement by an enormous mountain, the Monte Nuovo. Now, Pozzuolo is situated at the foot of Monte Nuovo. We need not add that the whole neighbourhood is volcanic. Pozzuolo touches on the Solfaterra, on the Lake Avernus, and is not far from Vesuvius; and in the bay is the monument of other days, erroneously called the Temple of Serapis. In reality it was most probably a thermal establishment, established for its mineral waters, although the world has agreed to call it a temple.

However that may be, the building has been nearly levelled by the hand of time, aided by the hand of man; and the ruins now consist of three magnificent marble columns of about forty feet high. But the curious and important fact is, that these three columns, at about ten feet above the surface, are riddled with holes, and full of cavities bored deeply into the marble, and these borings occupy the space of three feet on each column. The cause of these perforations is no longer doubtful. In some of the cavities the shell of the operator is still found, and it seems settled among naturalists that it belongs to a species of Pholas, although M. Pouchet, a naturalist of Rouen, denies this. "As far," he says, "as I have been able to judge from the fragment which I extracted from this temple, which is destitute of the hinge, it is infinitely more probable that this mollusc is a species of the genus Corallisphaga." In spite, however, of M. Pouchet's scepticism, the mass of evidence is opposed to his theory.

There are two modes of explaining the fact to which we have called attention. To enable the stone-boring molluscs which live only in the sea to excavate this marble, the temple and columns must have been buried several fathoms deep in sea-water. It is only in these conditions that the borers could have made an incision, and laboured at their ease, in the marble column.

But since the same traces of perforation are now visible ten feet above the surface, it follows that, after being long immersed under water, the columns have been elevated to their present position. The temple has been restored to its primitive state, carrying with it, engraved in marble, ineffaceable proofs of its immersion. Sir Charles Lyell has consecrated a long chapter to the successive sinking and elevation of this temple, which proves the fact most conclusively.

Family two, the Gastrochænidæ, is a somewhat heterogeneous one, as it contains Saxicava and Aspergillum. We have only space for a short account of the latter, the animal which has received the strange name of the Watering Pot, and is represented in Fig. 135. It inhabits a calcareous tube, thick, solid, of considerable length, and nearly cylindrical, presenting at one extremity an opening fringed with one or many foliaceous folds in the form of frills, and at the other extremity a convex disk, pierced with holes like a watering-pot: whence its name. The animal is attached by certain muscles to the interior of the tube. Chenu, to whom we are indebted for our information respecting this curious mollusc, tells us "that the animal which inhabits this curious shell was first described by Russell, whose account of it is deficient in the anatomical details, which might explain the utility of the holes in the disk of the central fissure, and of the spiriform tubes found there." We suppose that this arrangement is necessary in order to facilitate respiration; and M. De Blainville thinks the small tubes are intended for the passage of the fillets which are necessary to fix the animal to the body on which it is to live, and in such a manner as to admit of its movements round a fixed point.

Plate XX.—Temple of Serapis at Pozzuolo.

Fig. 135. Aspergillum
vaginiferum (Lamarck).

The animal which inhabits the Aspergillum is elongated, contractile, and only occupies the upper part of the tube, but it can stretch itself out sufficiently for all its wants. Shells of this genus are very rare, although a great number of species are known. They are found in the Red Sea, and in the seas of Australia and Java. The shells are generally of a white or yellowish tint; some have the tube covered with a glutinated sand, mixed with small fragments of shells of diverse colours. We know nothing of their habits, and their singular forms have left naturalists in doubt as to the place which should be assigned to them in the method of arrangement. It is only after having recognized the existence of two valves, which was detected with great difficulty just under the disk, and forming part of the sheath in which the animal is encased, that it has been decided to range them with the Tubicola, and with the shells presenting an arrangement analogous or equally singular. These molluscs are, as M. Chenu says, little known, rare, and hence much sought for by collectors. They are exclusively exotic, the most common species being from Java. It is imported into Europe by the Dutch. Our third family, the Anatinidæ, includes Myochama, Pandora, Lyonsia, Myacites, Pholadomya, Thracia, and Anatina, genera which were more important in the former than in the present seas; some, in fact, being wholly extinct, or represented, as in Pholadomya, by one or two living species. Our fourth family, the Myacidæ, including Gycimeris, is found only in America; Panopaæ, now principally extinct; Thetis, Neæra, Corbula, and Mya, or Gaper.

Our fifth family, Solenidæ, contains the Solens, which under the name of "razor-fish" are so abundant on the sandy shores of all parts of the globe. These molluscs live buried vertically in the sand, a short distance from the shore; the hole which they have hollowed, and which they never quit, sometimes attains as much as two yards in depth; by means of their foot, which is large, conical, swollen in the middle, and pointed at its extremity, they raise themselves with great agility to the entrance of their hole. They bury themselves rapidly, and disappear on the slightest approach of danger.

When the sea retires, the presence of the Solen is indicated by a small orifice in the sand, whence escape at intervals bubbles of air. In order to attract them to the surface, the fishermen throw into the hole a pinch of salt; immediately the sand becomes stirred, and the animal presents itself just above the point of its shell. It must be seized at once, for it disappears again very quickly, and no renewed efforts will bring it to the surface a second time. Its retreat is commonly cut short by a knife being passed below it; for it burrows into the ground with such velocity that it is difficult to capture it with the hands alone.

This shell has by some been compared to a knife-handle; by others to a razor, which has become its popular name. It is a thin, transparent, long, and slender equivalved bivalve, with parallel edges, gaping and truncated at both extremities. The tints are rose-coloured, bluish-grey, and violet; the valves slightly covered with an epidermis of a greenish brown.

The animal which lives in this elegant dwelling has the form of an elongated cylinder. Its mantle is closed in its whole length, and only open at the ends at one side for the passage of the food, and at the other for the passage of a tube formed of two syphons united together. This curious shell, various species of which are represented in Pl. XIX., are known as razor-fish, sabre-fish, and other names, which in some respects indicate the peculiar form of the shell, as well as its sharpness.

Plate XIX.—Razor-fish. Solenidæ.

I. Solen siliqua. (Linn.) II. Solen vagina. (Linn.)
III. Solen ensis. (Linn.) IV. Solen ensis major. (Lamarck.)
V. Solen ambiguus. (Lamarck.) VI. Solen legumen.

The Tellinidæ, the sixth family in our table, is very important, as including a vast number of genera and species, of which, as types, we will particularise Tellina and Donax; but Galatea, Mesodesma, Semele, Sanguinolaria, Psammobia, and Capsula, are important genera.

Along the shores of the Channel and in the Mediterranean there are few bivalves more abundant than the several species of the genus Donax. They live near the shore in shallow water, burying themselves perpendicularly in the sand. They have the very singular habit, considering their apparent helplessness, of being able to leap to a certain height and then project themselves ten or twelve inches. This may often be witnessed in the case of individuals left by the retreating tide. If seized by the hand, and attempts are made to disengage them from the sand, they continue to impress on their shell a sudden and energetic movement, aided by the elasticity of their foot, which is at once decisive and angular.

Fig. 136. Donax rugosus (Linnæus).

Fig. 137. Donax denticulatus.

The shell of the Donax is nearly triangular in shape, compressed, longer than it is high, regular, equivalve, not equilateral; the hinge with three or four teeth on each valve.

The animal is slightly compressed, and more or less triangular. Its mantle, which forms two symmetrical lobes enveloping the body, is open pretty nearly in all its extent, but it is united posteriorly, and terminates in two syphons or nearly equal tubes, as in Fig. 130, p. 326. One of these tubes serves the purpose of respiration: it is the bronchial syphon. The other, serving the purpose of ejecting the products of digestion, is termed the anal tube. The tentacles of the bronchial tube seem to be possessed of exquisite sensibility. When touched, the animal draws in its syphon, and only puts it forth anew when the danger has passed. The species of Donax are very numerous, especially in the Asiatic and American seas. Among the European species we may mention Donax rugosus (Fig. 136) and Donax denticulatus (Fig. 137).

Fig. 138. Tellina radiata (Linnæus).

Fig. 139. Tellina virgata (Linnæus).

Next to Donax naturalists rank the genus Tellina, which includes many species of very minute shells, all remarkable for their beauty of form, and for their brilliant and varied colours. One of these, called the Rising Sun (Tellina radiata), is represented in Fig. 138. The Tellinas are found in every sea; the French coast furnishes many species: examples, Tellina virgata (Fig. 139) and Tellina sulphurea (Lamarck) (Fig. 140). In Fig. 141 Tellina donacina is represented with its two vital tubes, or syphons.

Fig. 140. Tellina sulphurea (Lamarck).

Fig. 141. Tellina donacina (Linnæus).

The seventh family, or Mactridæ, include Lutraria and Mactra, or the otter and kneading-trough shells. They are widely distributed; there are several British species of both.

The eighth family, Veneridæ, includes Venus, Cytherea, Meroe, and Artemis; beautiful genera, and as such called by Linnæus and his followers after heroines of Greek mythology. Petricola, Venerupis, Tapes, Lucinopsis, and Trigona, also belong to the family. These acephalæ of size so small, like their congeners, inhabit every sea; they are found in every region of the globe, more than a hundred and fifty species being known. The shell is elliptic in form, the valves smooth, striated, spiny, and lamellous, like those of Cardium and Donax. Like these, they bury themselves in the sand.

Fig. 142. Venus verrucosa (Linnæus).

Fig. 143. Cytherea geographica (Chemnitz).

Among the vast number of species, many of them are extremely rare, and much sought after by collectors in consequence of their great beauty. In the principal ports of France, Venus verrucosa (Fig. 142), and another species known in the south of France under the name of Clovisse, are eaten there like oysters. Prepared with fine herbs, the Clovisse, we have M. Figuier's authority for saying, is not to be despised. "We may be believed also," he says, "if we add that nothing is more delicious than to eat the living Clovisse torn from the rock of the Phara of Lake Thau, when the Mediterranean sun of a day in winter is shining down upon us, the heart rejoicing in manhood's strength." In Pl. XVIII. some of the principal species are represented, along with some of the more remarkable species of Cytherea. In Fig. 143 we have the elegantly pencilled shell of Cytherea geographica, together with the animal in its natural connection.

The sub-section we shall now treat of is without the pallial line sinuated. The Cyprinidæ form the ninth family of our arrangement of the Conchifera, and contain, Cardia, Cypricardia, Isocardia, Crassatella, Astarte, Circe, and Cyprina, which amount together to some hundred species.

The Cycladidæ are our tenth family, and include Cyrenoides, Cyrena, Pisidium, and Cyclas.

The Lucinidæ is the eleventh family, containing Galeomma, Lepton, Montacuta, Kelia, Diplodonta, Corbis, and Lucina.

In the small family of which we have made the Tridacna the representative, as well as in some preceding families, the mantle of the animal is more or less largely open, but never with such a prolongation as to form tubes. In the Cardiums, now under consideration, as well as Donax, Tellina, and Venus, the respiratory organs are somewhat modified, so as to adapt them to the habits of the animal. All these molluscs live buried in the mud or sand, and two great tubes issuing from the interior of their bodies bring the atmospheric air into communication with their respiratory organ—namely, the branchial leaves.

The twelfth family, Cardiadæ, contains the familiar cockles—Cardium—which is derived from καρδὶα, a heart, which they are supposed to resemble in form, are amongst the most widely-distributed of shells. The shell is convex, as we see in C. hians (Fig. 144), somewhat heart-shaped, equivalved, the edges dentate or corrugated, the hinge furnished with four teeth upon each valve. The accessary ornaments vary with the species, some being smooth, as in Cardium Greenlandicum, Chemnitz (Fig. 145); others, and by far the greater number, are furnished with regular sides, generally obtuse, sometimes in ridges diverging from the point and armed with straight or curved spines, arranged in the oddest manner, as in Cardium aculeatum (Fig. 146).

Plate XVIII.—Venus and Cytherea.

I. Venus plicata. (Gmel.) II. Venus puerpera. (Linn.)
III. Venus reticulata. (Linn.) IV. Venus Gnidia. (Broderip.)
V. Cytherea zonaria. (Lamarck.)
VI. Cytherea petechialis. (Lamarck.)
VII. Cytherea maculata. (Linn.)

In C. hians (Fig. 144), the mantle has a large opening in front, fringed anteriorly with papillæ in the form of tentacula; the inhabitant of the shell has a very large foot, with a bend or knee near the middle; its mouth is transverse and funnel-shaped, and furnished with a triangular appendage. One of the peculiarities in the organization of these molluscs is its direct connection with their mode of life. In short, these molluscs, which most commonly live on the sea shore, and bury themselves in the sand to the depth of four or five inches, are enabled to breathe, to draw water for their nourishment, and also to throw off the products of digestion, by having the mantle prolonged into two tubes, the orifices of which reach to the surface of the soil. By means of these feet and an extremely curious organ of locomotion, the Cardiums can at will issue from their holes and re-enter them. The fishermen of the shore easily recognize the presence of these animals by the little jets of water which they throw up through the sands.

Fig. 144. Cardium hians (Brocchi).

Fig. 145. Cardium Greenlandicum (Chemnitz).

Fig. 146. Cardium aculeatum (Linnæus).

Fig. 147. Cardium edulis (Linnæus).

These molluscs are found in every sea on the globe, and under all latitudes. Many of them belong to our own and the French coasts, where they are eagerly sought for by collectors, as well as for food. The flesh of the animal, however, is coriaceous, and little esteemed. The species most common on the littoral of the Atlantic is Cardium edulis (Fig. 147), its white or fawn-coloured shell being hollowed out into six and twenty furrows, forming so many corrugated ripples on its side.

Fig. 148. Cardium costatum (Linnæus).

Cardium costatum (Fig. 148) is an exotic species which inhabits the coast of Guinea and the Senegal, the shell of which, white and fragile, is much sought after by collectors.

The thirteenth family of our table, Tridacnidæ, consists of only eight or ten species, but it contains the largest of all, the giant Tridacna. The historian of the wars of Alexander the Great speaks of oysters inhabiting the Indian Ocean which were more than a foot long; these were probably Tridacna, the shells of which were most likely to be seen by the Macedonian conquerors. The valves of Tridacna gigas are sometimes found a yard and a half in length, and weighing five hundred pounds. Magnificent examples may be seen in the church of Saint Sulpice, Paris, where they hold the holy water. These beautiful shells were the gift of the Venetian Republic to Francis I. Under Louis XIV., the curé Languet had them presented to the church of Saint Sulpice, where they are used as fonts for holy water. Another pair are exhibited in the church of Saint Eulala, at Montpelier, but much smaller in size. The shells of Tridacna are formed, as represented in Pl. XVII., of three acute angles, festooned on their edges by broad sides bristling with white scales. The hinges have two teeth; the ligament is elongated and external.

Plate XVII.—Tridacna gigantea, Holy Water Basin in the Church of Saint Sulpice at Paris.

The animal of Tridacna is remarkable for its fine colours. Tridacna safrana is of a beautiful blue round the edges, rayed through a shade of very pale blue. More in the interior is a row of small moons of a yellowish green; the centre is a bright violet, with brownish longitudinal punctured lines. "We have at this moment before our eyes," say the travellers Quoy and Gaimard, "one of the most charming spectacles that can be seen, when at a little depth beneath the surface a number of these animals display the brilliant velvety colours and varying shades of their submarine parterres. As we can only perceive the gaping opening of the valves, we may imagine to ourselves what is its first aspect." The mantle of the animal is closed and ample; its edges are swollen, and reunited in nearly its whole circumference in such a manner as to leave only three very small openings—two in the upper part; the one serves the purpose of discharging the products of digestion, the other gives entrance and exit to the water necessary for respiratory purposes. The third opening is in the lower part of the body, and free; it leaves an opening for the passage of the foot, which is enormous, and is surrounded with an ample tuft of byssoidal fibres.

Fig. 149. Tridacna squamosa (Lamarck).

Fig. 150. Tridacna squamosa, on the inside (Lamarck).

Aided by this silky tuft, the animal attaches itself to the rocks, and suspends its weighty shell from them. If it is intended to remove those attached to the sides of the rock, it is necessary to cut the cords of the tendonous byssus, by which it is held suspended, with a hatchet.

Fig. 151. Unio littoralis (Cuvier).

All the species are inhabitants of the Tropical seas. The Tridacna gigas is a native of the Indian Ocean. The flesh, though coriaceous, and by no means of an agreeable flavour, is a great resource to the poor Indians. The accompanying representations of Tridacna squamosa (Figs. 149 and 150) will convey a general idea of the genus.

Our fourteenth family, Hippuritidæ, is entirely fossil; but the fifteenth, Chamidæ, of which the best example is the rugose genus Charina, is widely distributed in tropical seas.

The very numerous division of shells called Asiphonidæ, possesses animals without respiratory siphons. The shells we shall now describe belong to the sixteenth family, Unionidæ, which contain Iridina, Anodon, and Unio.

The pond mussels, Anodon, are found in lakes, rivers, and seas of almost every region of the globe. Their shells are rounded or oval, generally very thin, regular, and equivalve, not gaping, the hinges without teeth, whence their name, from the Greek, ὀδότοϛ, without teeth. These shells are nacred inside, and generally smooth.

The Anodon cygnea (Fig. III., Pl. XVI.) is broad, deep, and light, and is sometimes employed for skimming the cream off milk. The genus is divided into many groups, the principal forms of which are represented in Pl. XVI.

The river mussels, Unio, are, like the Anodon, found in the muddy bottoms of all countries. The animal resembles the Anodon, but the shell presents a toothed hinge. The lower face of the valve is nacrous, but shaded with purplish violet, copreous, and iridescent; the anterior face is of a green colour, which varies from tender to blackish green.

Among the species found in European seas may be noted the Rhine mussel, a large species, the nacre of which is employed for ornamental purposes. Unio littoralis (Cuvier), represented in Fig. 151, and the painter's mussel, Unio pictorum (Fig. 152), employed in the arts to contain certain colours. Those known as the river mussels are leathery, of an insipid taste, and scarcely eatable: the finest species are found in the great American rivers.

Plate XVI.—Anodonta.

I. Anodonta angulata. (Lea.)
II. Anodonta ensiformis. (Spix.)
III. Anodonta cygnea. (Linn.)
IV. Anodonta magnifica. (Lea.)
V. Anodonta anserina. (Spix.)
VI. Anodonta latomarginata. (Lea.)

Mussels, as we have seen, produce pearls of moderate value. Linnæus, who was aware of the origin of the Pintadine pearls, and of pearls in general, was also aware of the possibility of producing them artificially from various molluscs. He suggested bringing together a number of mussels, piercing holes in their shells with an augur in order to produce a wound, and afterwards leave them for five or six years, to give the pearl time to form. The Swedish Government consented to try the experiment, and long did so in secret; pearls were produced, but they were of no value, and the enterprise was abandoned as unsuccessful.

Fig. 152. Unio pictorum (Linnæus).

Scottish pearls were much celebrated in the middle ages, and between the years 1761 and 1784 pearls to the value of £10,000 were sent to London from the rivers Tay and Isla; "and the trade carried on in the corresponding years in the present century," says Mr. Bertram, "is far more than double that amount." The pearl, according to Mr. Bertram, is found in a variety of the mussel, which is characterised by the valves being united by a broad hinge, and having a strong fibrous byssus, with which it attaches itself to other shells, to rocks, and other solid substances. "The pearl fisheries of Scotland," he adds, "may become a source of wealth to the people living on the large rivers, if prudently conducted." Mr. Unger, a dealer in gems in Edinburgh, having discerned the capabilities of the Scotch pearl as a gem of value, has established a scale of prices which he gives for them, according to their size and quality; and it is now a fact that the beautiful pearls of our Scottish streams are admired beyond the orient pearl. Empresses and queens, and royal and noble ladies, have made large purchases of these gems; and Mr. Unger estimates the sum paid to pearl-finders in the summer of 1864 at £10,000. The localities successfully fished have been the classic Doon, the Forth, the Tay, the Don, the Spey, the Isla, and most of the Highland rivers of note. Scottish pearls are much whiter in colour than oriental. What tint they have is bluish, while those of the East are yellowish. Pink pearls are produced by several exotic species of Unio.

Our seventeenth family are the Trigoniadæ, affording Trigonia, of which so many occurred in the Jurassic period of Geologic History in the strata of Europe, but of which two or three are alone left alive in the seas of Australia.

The eighteenth family, the Arcadæ, affords between 200 and 300 species of the families of Leda, Nucula, Pectunculus, and Arca.

Of the eighteenth family, Arcadæ, we shall only at present instance Pectunculus.

Fig. 153. Pectunculus aureflua (Reeve).

Fig. 154. Pectunculus delessertii (Reeve).

The genus Pectunculus are abundant on the shores of the Mediterranean and along the Atlantic coast. If we take up at hazard a handful of shells on any part of the French coast, one-third will consist of Pectunculus. They are found mixed with Cardium, Venus, Razor-fish, and Pectens. Their round and robust frame attracts much attention. They form the first of those charming infantile collections which are gathered at the mother's feet.

The animal which inhabits this pretty shell is moulded on its curvature; like the shell, it is round and squat; it is furnished with a mouth, large, and thick for its size, and with double branchiæ. When the animal is taken alive, it sometimes exudes a thick mucous liquid over the shell, which has disgusted many a young collector with his capture.

Among numerous species of Pectunculus we note as worthy of representation: P. aureflua, Reeve (Fig. 153); P. delessertii, Reeve (Fig. 154); P. pectiniformis, Lamarck (Fig. 155); and P. scriptus, Born (Fig. 156).

Fig. 155. Pectunculus pectiniformis (Lamarck).

Fig. 156. Pectunculus scriptus (Born).


CHAPTER XII.

ACEPHALOUS MOLLUSCA—continued.

MYTILIDÆ—THE MUSSEL.

"Ecce inter virides jactatur mytilus algas."
Anthologia.

We shall now consider the nineteenth family or Mytilidæ, which includes Mytilus, Modiola, Lithodomus, and Dreissena.

Fig. 157. Mytilus edulis (Linnæus).

The well-known shell of the mussel (Fig. 157, Mytilus edulis) is longitudinal, equivalve, and regular, pointed at the base, with capacity to attach itself by a byssus; the hinge has no teeth, but a deep furrow, in which the ligament is located. In the genus Mytilus the byssus is divided to its base. In Modiola it has a common corneous centre. In Pinna the anus is furnished with a long angular base. In all these genera the foot is small, its retractile muscles numerous, and the byssus large. In Lithodomus the byssus is rudimentary; the muscles are retractile, equal, and two pairs only. In Unio, Cardium, and Hyria, the foot is large and not byssiferous.

The animal, as described by M. Chenu, is elongate, oval, the lobes of the mantle simple or fringed, divided at the edge into two leaves, the interior being very short, bearing a fringe of small, cylindrical, and movable fillets; the exterior leaf is united to the shell very near the edge. The opening by which water and food are introduced supplies the branchiæ at the same time. The stomach consists of a white membrane, thin, like opaline, and presenting itself in longitudinal folds; the liver is granulous, composed of greenish grains more or less deep, contained in the meshes of a whitish tissue forming a thickish bed, which surrounds the stomach, the intestines taking the direction of the median and dorsal line, and beneath the heart are received and terminate in a small appendage, floating in the cavity of the mantle near the hinge. The foot is, perhaps, the remarkable organ of the mussel: it is small, semi-lunar when not in motion, but capable of great elongation, resembling thus a sort of conical tongue, having a longitudinal furrow on its side. It is put in motion by several pairs of muscles, all of which penetrate and are interlaced with the tissue; behind it is the silky byssus. The mouth is large, and furnished with two pairs of soft palpi, which are pointed and fixed by their summit. Abdominal masses emanate, and on each side a pair of nearly equal branchiæ. The additional muscles, one anterior and small, the other posterior, large, and rounded. At the base of the foot is a gland which furnishes a viscous secretion; this viscous liquid is organized and moulded in the groove of the foot, and forms a thread, and originates the byssus; it is a bundle of hairs, mane, or thread, which holds on to its shell.

The byssus plays an important part in the organization of the mussel. While the oyster remains eternally riveted to its rock, until torn from it by violence, the mussel moves about, and in this motion the byssus is an active agent. The mussel attaches its byssus to some fixed object, and drawing upon it, as upon a line, the shell is displaced. The house is drawn onwards; the animal is in motion. It takes no great strides, but a fraction of an inch satisfies its desires; it is, however, an advance upon the oyster, and a lesson in mechanics. The mussel stretches out its foot, and, at the point chosen, it hooks on a hair of the byssus; then, withdrawing the foot suddenly, and hauling on the thread, the animal and shell are moved forward. Every time it repeats this motion it seems to attach an additional hair, so that at the end of the four and twenty hours it has used many inches in length of cordage. In the byssus of some mussels we find as many as a hundred and fifty of these small threads, with which the animal anchors itself most securely to the rock. Aided by this cordage, the mussel suspends itself to vertical rocks, holding on a little above the surface of the water, so that the shell is smooth and polished as compared with the coarse and rugged shell of the oyster.

The mussels, like the oysters, are gregarious, and widely diffused over all European seas. They abound on both sides the Channel, their lower price having procured for them the name of "the poor man's oyster;" but it is infinitely less digestible and savoury than its congener.

Fig. 158. Byssus, mantle, and oviduct.

a, right lobe of the mantle; d, rectum; g, branchiæ; h, foot;
j, posterior muscle; l, superior tube;
o, heart; p, ventricle; q, auricle; x, pericardium; b, tentacles;
d, byssus; e, gland of the byssus;
g, retractile muscle of the foot; h, valves of the mantle; i, oviduct;
j, orifice of the excretory organ; k, internal ditto.

Many of our readers may think that mussels are found on the shore in a state of nature, of good size, well flavoured, and fit for the table. Nothing of the kind! Detached from the rocks and cliffs of the sea, where it has been growing in a natural state, it is lean, small, acrid, and unwholesome food; and it is only when human industry intervenes to ameliorate this child of Nature that it becomes palatable and wholesome food. In order to trace the ameliorative process by which the coriaceous flesh of the mussel was rendered tender, fat, and even savoury, we must conduct the reader back into the middle ages.

Some time in 1236 a barque, freighted with sheep and manned by three Irishmen, came to grief upon the rocks in the creek of Aiguillon, a few miles from Rochelle. The neighbouring fishermen who came to the relief of the crew succeeded with great difficulty in saving the life of the master, a man named Walton. Exiled upon the lonely shore of the Aunis, with a few sheep saved from shipwreck, Walton at first supported himself by hunting sea-fowl, which frequented the shore and neighbouring marshes in vast flocks. He was a skilful fowler, and invented or adapted a peculiar kind of net, which he called the night net. This consisted of a net some three or four hundred yards in length by three in breadth, which he placed horizontally, like a screen, along the quiet waters of the bay, retaining it in its position by means of posts driven into the muddy bottom. In the obscurity of the night the wild-fowl, in floating along the surface of the waters, would come in contact with the net, and get themselves entangled in its meshes.

But the Bay of Aiguillon was only a vast lake of mud, in which boats moved with difficulty; and Walton, having arranged his bird-net, began to consider what kind of boat would enable him most conveniently to navigate the sea of mud. The flat-bottomed, square-sided boat, known in our rivers as a punt, and on the Norman coast as an acon, was the result. Walton's boat had a wooden frame some three yards long and one in breadth and depth, the fore part of which sloped down into the water, in the form of a prow, at a slight angle. In propelling the boat the rower, who occupied the stern of the punt, knelt on his right knee (as represented in Fig. 159), inclining forward, with one hand on each edge, and the left leg outside the boat. A vigorous push with the left foot gave the frail boat an impulse, under which it rapidly traversed the bay from one point to the other.

The mussels swarmed in the little bay; and Walton soon remarked that they attached themselves by preference to that part of the post a little above the mud, and that those so placed soon became fatter, as well as more agreeable to the taste, than those buried in the mud. He saw in this peculiarity the elements of a sort of mussel culture which might become a new branch of industry. "The practices he introduced," says M. Coste, "were so happily adapted to the requirements of the new industry, that, after six centuries, they are still the rules by which the rich patrimony he created for a numerous population is governed. He seems to have applied himself to the enterprise, conscious not only of the service he was rendering to his contemporaries, but desirous that their descendants should remember him, for in every instance he has given to the apparatus which he invented the form of his initial letter W. After due consideration, Walton began to carry out his design. He planted a long range of piles along the low marshy shore, each pair forming a letter V, the front of the letter being towards the sea, and each limb diverging at an angle of forty-five degrees. These posts were driven about a yard asunder; they were about twelve feet long, six feet being above water, and interlaced with branches wattled together, so as to form continuous hurdles, each about two hundred yards long, which are called bouchots. By the assistance of this apparatus, which intercepted spat which would otherwise have been swept away to sea by the tide, Walton formed a magnificent collection of mussels; but he did not abandon his isolated piles. These, being without fascines or branches, and always submerged, arrested the spat at the moment of emission."

Fig. 159. Punt or Pirogue of the Marsh.

The advantages of this system of culture adopted by the Irish exile were so obvious that his neighbours along the shore were not slow to imitate his example. In a short time the whole bay was covered with similar bouchots. At the present time these lines of hurdles form a perfect forest in the little creek. About two hundred and thirty thousand piles support a hundred and twenty-five thousand fascines, which, according to M. Coste, "bend all the year under a harvest which a squadron of ships of the line would fail to float." There are about five hundred of these bouchots in the bay, each from two hundred to two hundred and fifty yards in length and six feet high.

Fig. 160. Isolated piles covered with the spawn of mussels.

The isolated piles are without palisades, and are uncovered only at spring tides. In the months of February and March the spat collected on them scarcely equals in size a grain of linseed; by the month of May it will be about the size of a split pea; in July, a small haricot bean: this is the moment for its transplantation. In this month the bouchotiers, as the men occupied in this culture are called, launch their punts and proceed to the part of the bay where these piles are driven. They detach with a hook the agglomerated masses of young mussels, which they gather in baskets, and carry them to their bouchots. These bouchots, that is to say, the piles covered with fascines and branches, are of four different heights, forming, so to speak, four stages, according to the age and growth of the mussel. Each stage receives the mollusc suitable to it. In the first stage of its existence the mussel cannot endure exposure to the air, and remains constantly under water, except at the period of spring tides. These are gathered in sacks made of old matting, or suspended in interstices of the basket-work. "These immense palisades," says M. Coste, "cover themselves with black clusters of mussels developed between the meshes of their tissues." At that time the second rows are cleared away to make room for younger generations; the mussels, which no longer dread the air, are transported to the more advanced bouchots, which remain above water in all tides, where they stay till they are fit for market, which usually happens after ten or twelve months of culture on the more advanced bouchots.

Fig. 161. Piles, with basket-work, covered with mussels in a fit state to be gathered in.

But, in order to prepare for this consummation, they are subjected to a second and even a third remove. There is no longer any danger in subjecting them to the air for many hours. From this they pass to a fourth stage, termed Amont (Fig. 161). From this stage the full-grown mussel is removed. Under this system of culture the reproduction, nursing, collecting, and preparing for market, are made simultaneously. From July to January the mussel trade is in full operation, and the flesh in perfection. From February to April is the close season; their flesh is then poor and leathery. It is also remarked that those which inhabit the upper rows of the wicker-work are of a mellower flavour than those on the lower ranks, and that the intermediate rows are an improvement on those which are buried in the mud, although even these are preferable to mussels gathered on the sea shore in a state of nature.

M. Coste gives a graphic description of the manner in which this industry is carried on. "Having supplied the neighbouring villages," he says, "for the purpose of supplying the more distant cities, the bouchotiers land their punts, filled with mussels, which their wives carry into grottoes hollowed out of the cliffs; where they clean and pack them in hampers, baskets, and panniers, for conveyance by carts or pack-horses. They depart on their respective journeys at night, so as to reach their markets at La Rochelle, Rochefort, Surgéres, Saint-Jean-d'Angely, Angoulême, Niort, Poictiers, Tours, Angers, and Saumur, at an early hour. A hundred and forty horses and ninety carts make upwards of thirty-three thousand journeys annually to these cities. Besides this, forty or fifty boats come from Bordeaux, the isles of Ré and Oleron, and from the sands of Olonne, making an aggregate of seven hundred and fifty voyages per annum, distributing the harvest of the little bay at places where horses could not serve the purpose.

"A bouchot, well furnished, supplies annually, according to the length of its wings, from four to five hundred charges. The charge is a hundred and fifty kilogrammes (over three hundred pounds), and sells for five francs; a single bouchot thus carries a harvest equal in weight to a hundred and thirty to a hundred and forty thousand pounds, equal in value to £100; the whole bay probably yielding a gross revenue of £480,000. This figure, and the abundant harvest which produces it, gives only a slight idea of the alimentary resources of the sea shore; and every part of the coast, properly adapted for the purpose, could be turned to equal advantage. In the mean time, the Bay of Aiguillon remains a monument of what one man may accomplish."