cious quality to the oyster, probably by acting as the cause of some disease. The fact was communicated to Dr. Chisholm, "at St. Croix, by the late Mr. William Newton, of that island. Some time after the Santa Monica, British frigate, was cast away on the coast of the island of St. John, one of the Virgin Islands, oysters grew on her bottom, which was coppered. Many people ate of these oysters, and although the consequence was in no instance fatal, it was such as was dangerous and unpleasant in a very great degree, producing cholera and excruciating tormina."* Further observations and experiments are, however, necessary to elucidate this interesting question. Lamouroux states that mussels never become poisonous unless they are exposed alternately to the air and the sea in their place of attachment, and unless the sea flows in gently over them without any surf; but on this statement it may be remarked that mussels are almost always found in such localities, where they certainly thrive best. * Edin. Med. Surg. Journ. iv. 400. 23 LETTER III. THE MOLLUSCA CONSIDERED AS EDIBLE ANIMALS. You may often have heard it observed that living beings form an uninterrupted chain, from which no link can be removed without disordering the uniformity of the whole. The comparison, in whichever way applied, is not altogether correct; for there are yet at least many evident breaks to the continuity of animals, many incompleted or absent circles in the scheme of their quinary involutions, whether we look to their external appearance or internal organization. If the simile is intended merely as an illustration of their dependence upon one another for the supply of some necessary want, it is still liable to exception, for there can be no doubt that many species of the Mollusca in particular, which have lived under the present state of things, have been lost and exterminated, while others their contemporaries survive to play their part among living entities. You must therefore receive with many limitations the language of some writers, who love to declaim upon the possible effects of the annihilation of even the most insignificant species. It might involve, they say, the destruction of some other immediately dependent on it for its wants; the extermination of this again would be but the precursor of another's death; another still would succeed, and ruin would spread around, until man himself fell in its embrace. Impressed with this view, which is a very popular one, a poet and naturalist has said, "Each shell, each crawling insect holds a rank Stillingfleet's Select Works, ii. i. 46. See Cuvier's remarks on this subject in his Hist. des Sc. Nat. iii. p. 54, &c. ; and Miller's Old Red Sandstone, p. 66. It is by thus associating it with religious sentiment-with the presumed immutability and perfection of the present system-that currency has been given to the opinion: but truly the existence of animals and of man is held on no such slight and uncertain tenure, and it has been proved that the extinction of many species has been attended with no ruinous result.* That animals are nevertheless more or less dependent on one another is evident: one species may disappear, and its loss be unfelt; but were the process of extinction to proceed from species to races and families, the resources of some of the remainder must fail, and it is improbable that their constitutions would be pliable enough to accommodate itself without injury to subsistence of a new character. It is in fact the dependency which animals have upon each other for a supply of necessary food, that mainly concatenates the whole. On contemplating this part of creation, we behold a scene of havoc and devastation perpetually and everywhere going on, so that "there is not," as Smellie has remarked, perhaps a single species (or family) of animated beings, whose existence depends not, more or less, upon the death and destruction of others." That this order of things, however cruel it may appear to us, is subservient to the good of the whole, cannot admit of any doubt; and it is my purpose, in the present letter, to convince you by some detail of facts, that molluscous animals in this relation play a not unimportant part. But, as it would be tedious to enumerate all or the greater portion of the animals to which they furnish nutriment, we shall confine ourselves to those which possess some peculiar interest, or which minister directly to the luxuries or necessities of man. To commence with quadrupeds and mammals. It is nothing surprising that the different species of walrus and narwhales, inhabitants of ocean, should feed partly or principally on cuttles and shell-fish; nor that the whale should obtain a large proportion of the nutriment for its huge growth from the myriads of little pteropod Mollusca, which crowd the Arctic seas; but perhaps you would not expect to find among molluscous feeders animals which are strictly terrestrial. Yet the ouran-outang and the preacher-monkey, it is said, often descend to the sea to devour what shell-fish they may find strewed upon the shores. The former, according to Carreri Gemelli, feed in particular on a large species of *Lyell's Geology, ii. 128. + Mr. C. Darwin has some interesting remarks bearing on this question in the Voy. of the Adventure and Beagle, 304-5. Ent. Mag. iii. 433. oyster, and fearful of inserting their paws between the open valves, lest the oyster should close and crush them, they first place a tolerably large stone within the shell, and then drag The latter are no less ingeout their victim with safety. nious. Dampier saw several of them take up oysters from the beach, lay them on a stone, and beat them with another till they demolished the shells. Wafer observed the monkeys in the island of Gorgonia to proceed in a similar manner; † and those of the Cape of Good Hope, if we are to credit La Loubere, perpetually amuse themselves by transporting shells from the shore to the tops of the mountains, ‡ with the intention undoubtedly of devouring them at leisure. Even the fox, when pressed by hunger, will deign to eat mussels and other bivalves; and the racoon, whose fur is esteemed by hatters next in value to that of the beaver, when near the shore lives much on them, more particularly on oysters. We are told that it will watch the opening of the shells, dexterously put in its paw, and tear out the contents; but when it is added that the oyster, by a sudden closure of its shell, occasionally catches the thief and detains him until he is drowned by the return of the tide, the story assumes a very apocryphal character. § The American musk-rat, and an animal allied to it in New South Wales, feed on the large mussels so abundant in the rivers and lagoons of those countries; the animals dive for the shells and drag them to the land, where they break them and devour the inmates at leiislets many sure. Our own brown rat, having settled in at a great distance from the large islands of the outer Hebrides, finds means of existence there in the shell-fish and crustacea of the shore; and according to Mr. Jesse, the same rat, we must "To this instance of instinct, however," says Mr. Swainson, withhold our belief: it is not only too rational, but there is nothing yet known, to make us believe that this quadruped feeds, in a state of nature, upon animal food."-On the Hab. and Inst. of Anim. in Lard. Cyclop. p. 21. + Bingley's Animal Biography. ron. Buffon Nat. Hist. Eng. Trans. i. 221. "The Inverness Courier' states that immense mussels, some of which are almost as large as a man's shoe, are found at Ardinisgain, on Loch CarA few days since, one of these mussels was left uncovered by a spring ebb tide, and was induced by the rays of the sun to open itself. While thus open, it was observed by a prowling fox, which thrust its tongue into the shell in the hope of securing the fish; but the mussel instantly closed on the tongue of the fox, which was retained a prisoner until drowned by the rising tide."— Berwick Advertiser, Jan. 15, 1848. We hope that the fact is not as false as the grammar. || Cunningham's N. S. Wales, i. 311. satiated it may be with the common fare, will sometimes select the common brown snail (Helix aspersa) as a pleasant entremet.* In some parts of England it is a prevalent and probably a correct opinion, that the shelled snails contribute much to the fattening of their sheep. On the hill above Whitsand Bay, in Cornwall, and in the south of Devonshire, the Bulimus acutus (Fig. 3, a), and the Helix virgata (b), Fig. 3. which are found there in vast profusion, are considered to have this good effect; and it is indeed impossible that the sheep can browse on the short grass of the places just mentioned, without devouring a prodigious quantity of them, especially in the night, or after rain, when the Bulimi and Helices ascend the stunted blades. "The sweetest mutton," says Borlase, "is reckoned to be that of the smallest sheep, which usually feed on the commons where the sands are scarce covered with the green sod, and the grass exceedingly short; such are the towens or sand hillocks in Piran Sand, Gwythien, Philac, and Senan-green near the Land's End, and elsewhere in like situations. From these sands come forth snails of the turbinated kind, but of different species, and all sizes, from the adult to the smallest just from the egg; these spread themselves over the plains early in the morning, and whilst they are in quest of their own food among the dews, yield a most fattening nourishment to the sheep."+ Among birds the Mollusca have many enemies. Several of the duck and gull tribes, as you might anticipate, derive at * Gleanings, second series, 316.-" A tradesman of Plymouth, having lately placed some oysters in a cupboard, was surprised at finding, in the morning, a mouse caught by the tail, by the sudden collapsing of the shell. About forty years since at Ashburton, at the house of Mrs. Allridge, known by the name of the New Inn, a dish of Wembury oysters was laid in a cellar. A large oyster soon expanded its shell, and at the instant two mice pounced upon the living luxury,' and were at once crushed between the valves. The oyster, with the two mice dangling from its shell, was for a long time exhibited as a curiosity. Carew, in his History of Cornwall,' tells of an oyster that closed on three mice.-Bell's Weekly Messenger for Jan. 7, 1821. An apposite instance is also epigrammatically recorded in the "Greek Anthology "Omnia contrectans, lychnos quoque rodere suetus, Mus, labiis concham forte patere videt. Sed cupido falsam morsu vix attigit escam + Hist. of Cornwall, 286. |