their own food among the dews, yield a most fattening nourishment to the sheep." (Hist. of Cornwall, p. 286.) In Among birds the Mollúsca have many enemies. Several of the duck and gull tribes, as you might anticipate, derive at least a portion of their subsistence from them. The pied oyster-catcher receives its name from the circumstance of feeding on oysters and limpets (Patélla vulgàris), and its bill is so well adapted to the purpose of forcing asunder the valves of the one, and of raising the other from the rock, that "the Author of Nature," as Derham 66 says, seems to have framed it purely for that use." Several kinds of crows likewise prey upon shellfish, and the manner in which they force the strong hold of their victims is very remarkable. A friend of Dr. Darwin's saw above a hundred crows, on the northern coast of Ireland, at once, preying upon muscles. Each crow took a muscle up in the air twenty or forty yards high, and let it fall on the stones, and thus broke the shell. Many authorities might be adduced in corrobation of this statement. Southern Africa so many of the Testàcea are consumed by these and other birds, as to have given rise to an opinion that the marine shells found buried in the distant plains, or in the sides of the mountains, have been carried there by their agency, and not, as is generally supposed, by eruptions of the sea. Mr. Barrow, who is of this opinion, tells us, in confirmation of it, that "there is scarcely a sheltered cavern in the sides of the mountains that arise immediately from the sea, where living shellfish may not be found any day of the year. Crows even, and vultures, as well as aquatic birds, detach the shellfish from the rocks, and mount with them into the air shells thus carried are said to be frequently found on the very summit even of the Table Mountain. In one cavern at the point of Mussel Bay," he adds, "I disturbed some thousands of birds, and found as many thousands of living shellfish scattered on the surface of a heap of shells, that for aught I know, would have filled as many thousand waggons." * The story, therefore, of the ancient philosopher whose bald pate one of these unlucky birds mistook for a stone, and dropped a shell upon it, thereby killing at once both, is not so tramontane as to stumble all belief. Land shells furnish a few birds with part of their sustenance, and the principal of these are two well known songsters, the blackbird and the thrush. They, "whose notes Nice finger'd Art must emulate in vain,” * Travels in Southern Africa, i. 8. 4to. 1806. depend in great measure, when winter has destroyed their summer food, on the more common species of Hélices, especially on H. nemoralis. These they break very dexterously by reiterated strokes against some stone; and it is not uncommon to find a great quantity of fragments of shells together, as if brought to one particular stone for this very purpose. Fishes are stupid animals, and incapable apparently of planning any stratagem by which they might surprise the unheeding conch. You might imagine, therefore, that our favourites," in their grotto works enclosed," were sufficiently secure from their hostile attempts. It is not so. They are the frequent victims, not indeed of the cunning, but of the indiscriminating and almost insatiable appetite, of fishes; and from the stomach of a cod or flounder you may procure many a shell, not otherwise so easily attainable. When indeed we call to recollection the vast and incalculable numbers of molluscous animals which crawl on the bottom, or swim in the bosom, of the ocean, and the voracious habits of the swarms of fish which every where traverse it, we may reasonably conclude that their utility in this respect in the economy of nature is very great, and beyond human ken. And not only do the shellfish nourish, but it has been presumed, or perhaps proved, that they impart a peculiar flavour to at least some of their devourers, which greatly enhanced their value in the esteem of Roman epicures. Thus Martial sings "No praise, no price a gilthead e'er will take, and, according to Pliny, the mullets which savoured of their food were the most prized "laudatissimi conchylium sapiunt ;" and these, as saith honest Izaak Walton, they would purchase at rates, rather to be wondered at than believed." I must here digress a little, to advert to the more direct utility of the Mollúsca in furnishing to the fisherman the means of enticing to his snare the hapless victims of his art. On every coast the shellfish peculiar to it are extensively employed for this purpose, but we may confine ourselves to those used by our own fishermen. At Salcomb on the coast of South Devon the Phòlas dáctylus is found in great abundance, and is used * Montagu, Ornithological Dictionary. + Hence Pope in his Satires, "Let me extol a cat on oysters fed; I'll have a party at the Bedford-head." ["The most prized savour of shell-fish.”]. with success. Many boat-loads of a river muscle (U`nio margaritífera Turton) are taken from the mouth of the Ythen, a river not far from Aberdeen, and employed in the fisheries of cod and ling established near Peterhead. The clam (Pécten operculàris) and the great muscle (Modiola vulgàris) are resorted to in other parts of the kingdom, and are eagerly sought after as a bait for cod; and you are aware that many thousands of limpets (Patélla vulgaris) and of the common muscle (Mýtilus edulis) are daily torn from the rocks, to ensnare the common fishes of our coasts, and thus contribute materially to add one more luxury to the tables of the rich, and to give to the poor a cheap and wholesome diet. The large whelk (Búccinum undàtum) and a species of rock-shell (Murex despéctus Mont.) may likewise be enumerated among our ordinary baits; but the most valuable of the class is certainly the Loligo vulgàris (fig. 41.), or, as it is called by our fishermen, the sleeve or hoe-fish. With this animal one half of all the cod taken at Newfoundland is caught. It appears there in throngs about the beginning of August, and seems to succeed to the capelin (the fish with which the other half is taken), as if to supply, immediately, provision to the cod, the traffic in which "brings wealth to individuals and strength to the state." It begins to retire from the coast in September. "During violent gales of winds, hundreds of tons of them are often thrown up together in beds on the flat beaches, the decay of which spreads an intolerable effluvium around. It is made no use of except for bait; and as it maintains itself in deeper water than the capelin, instead of nets being used to take it, it is. jigged,-a jigger being a number of hooks radiating from a fixed centre, made for the purpose. The cod is in best con "The Edin. New Phil. Jour. No. i. p. 37. The editor remarks: cuttle-fish occurs in abundance in many of our estuaries and coasts, but has hitherto been considered as of no value. Now that it is known to form an excellent bait for cod, and even for other fishing, it is not to be doubted that it will in future, in this country, be used with equal advantage and profit as a bait for the capture of our cod, ling, &c." VOL. II. No. 7. M Crowds of the inferior animals certainly feed on the Mollúsca, but as there is little interest in the detail, a very few examples will here suffice. Two small leeches (Hirùdo bioculàta and complanata) often wage successful war against the fresh-water snails so abundant in our ditches; and another species (H. hyálina), not so cruel in disposition, draws its nourishment. from the sanies which flows from the Planórbis carinàtus. Its calcareous envelope is no protection to the muscle against the wiles of the Nýmphon gróssipes; thousands of littoral shells are devoured by the sea anemones (Actínia); and the common star-fish knows so well how to force the oyster from his close retreat *, and destroys such numbers of them, that every dredger who observes one of their enemies, and does not tread on and kill it, or throw it upon the shore, is liable to some penalty. As ultimately connected with our subject, I must now inform you that to some animals among the inferior tribes, shells afford a house and a place of refuge, as necessary to them as either air or food. The turbinated univalves become, after the death of their proper owners, the habitations of the soldier or hermit crabs (Pagurus Leach), whose naked and slender abdomens, covered merely with a skin of a delicate texture, would, without this foreign covering, be crushed to pieces in the strife of waves and rocks to which they are exposed, or devoured by the enemies which surround them. A singular species of soft worm, or Siphúnculus, discovered by Mr. Montagu, inhabits old and worn specimens of the Strómbus pès Pelecàni Lin., whose aperture it closes up with agglutinated sand, leaving only a small round hole, within which it lives in security; and another species not yet described, though common on the coasts of Scotland, takes possession of the common tooth-shell (Dentalium entàlis), and secures the aperture in the same manner. The beautiful and delicate Paper Nautilus, with whose interesting history you must be, at least, partially acquainted, is not navigated over the surface of its native ocean by its own architect, but by a species or Ocýthoe, or cuttle-fish, its parasitic inhabitant. This surprising fact was long disputed amongst naturalists; but the specimens brought to England by the gentlemen of the unfortunate Congo expedition, have enabled Dr. Leach and others to give it very great probabi "The prickly star creeps on with fell deceit, Jones. lity, if not to demonstrate its truth. Mr. Cranch tells us, that, having placed two living specimens in a vessel of sea-water, the animals very soon protruded their arms, and swam on and below the surface, having all the actions of the common cuttle of our seas. By means of their suckers they adhered firmly to any substance with which they came in contact, and when sticking to the sides of the basin the shell might easily be withdrawn from the animals. They had the power of retiring completely within the shell, and of leaving it entirely.* One individual quitted its shell, and lived several hours, swimming about, and showing no inclination to return into it; and others left the shells as they were taken up in the net. The observations of Sir Everard Home are, perhaps, no less decisive, confirmed, as they have been, by subsequent naturalists. He found the ova of the animal caught in the Argonaúta (so the shell is known in science) to differ from those of every other testaceous animal that lives in water, in having a very large yolk to supply the young with nourishment after they are hatched, and in not being enclosed in a camerated nidus, or chambers of a peculiar kind, which are a necessary defence in the period between the egg being hatched and the young acquiring its shell.+ I shall leave you to your own reflections upon this fact. It is not the least remarkable of the marvellous works with which Infinite Wisdom has stored this world. 66 Wonderful, indeed, are all His works, G. I. ART. VIII. An Introductory View of the Linnean System of Plants. By Miss KENT, Authoress of Flora Doméstica, Sylvan Sketches, &c. (Continued from Vol. I. p. 436.) LEAVES assume an endless variety of forms and combinations; some are shaped like an egg, some like a heart, some like a fiddle, some like a hatchet, &c. Others are compound; composed of many small leaves called leaflets, which, * Aristotle knew that the animal of his Naútilus was not naturally connected with the shell. (De Nat. Animal., lib. iv. cap. ii. sect. 54.) + Tuckey's Narrative of an Expedition to the Zaire, appendices ii. and iii. Mr. Broderip, in an interesting essay on this subject in No. xiii. of the Zoological Journal, considers the question still undecided; but his observations upon the whole, in my opinion, support the view I have taken. |