the SCALLOP; a genus of shell-fish, the characters of which are these: The animal is a tethys; the shell bivalve and unequal; the hinge toothless, having a small ovated hollow. This shell-fish is one of the spinners, having the power of spinning threads like the mussels; but they are much shorter and coarser than even those of that fish; so that they can never be wrought into any kind of work like the longer and finer threads of the pinna marina. The use of the threads which are spun by the scallops is to fix the creature to any solid body near its shell. All these proceed, as in the mussel, from one common trunk. It is an evident proof that the fish has a power of fixing itself at pleasure to any solid body by means of these threads, that after storms the scallops are often found tossed upon rocks, where there were none the day before; and yet these are fixed by their threads, as well as those which had remained ever so long in their place. They form their threads in the very same manner which the mussel; only their organ which serves for spinning is shorter, and has a wider hollow, whence the threads are necessarily thicker and shorter.

Mr Barbut divides the genus ostrea into four families; which he thus names according to their characters. 1. The winged equilateral pectens. 2. The pectens, that have one ear inwardly, spring by being calcified. 3. The pectens that have their valves more gibbous on one side than on the other. 4. The rough ones, commonly called oysters. Of the locomotive powers of the pecten, we have already treated under the article Animal Motion, which see p. 411, col. 2.

The pectens, such as the sole-pecten, the ducal mantle pecten, the knotted, and others, seem to be in general inhabitants of the Indian seas; some of them frequent those of Africa and the South Seas. The most remarkable species is the maximus or great scallop, being the same with what Barbut calls the ducal-mantle pecten. It has 14 rays, very prominent and broad, and striated both above and below. They are rugged and imbricated with scales. They grow to a large size; are found in beds by themselves; are dredged up, and barrelled for sale. The ancients say that they have a power of removing themselves from place to place by vast springs or leaps. This shell was used both by the Greeks and Latins as a food. When dressed with pepper and cummin, it was taken medicinally. The scallop was commonly worn by pilgrims on their hat, or the cape of their coat, as a mark that they had crossed the sea in their way to the Holy Land, or some distant object of devotion.

The name pecten seems to have been given to these animals, from the longitudinal striae with which their surface is covered, which resemble somewhat the teeth of a comb; and hence also the Greek name κτενος. By the general character of this shell, it evidently includes cockles as well as scallops, which are the pectens without ears, and having less flat or elated shells. They are called by all authors by a name which is only a diminutive of pecten, pectunculus. The having ears indeed is the common mark of distinction between the pectens and the cockles, which last usually have none; yet the genera are not distinct, as some have imagined: for there are shells universally allowed to be pectens or scallops, which have no ears, and others as universally allowed to be pectuncles or cockles which have. Hence then appears the error of Lister, who made them two distinct genera, and gave the ears and the equal convexity of both shells as the great characteristics of them; which, though they be good marks to distinguish the species by, are far from being so unalterable as to found different genera upon.

Barbut, we have seen, ranks the pectens under the genus ostrea; but he says, that though the generic character of the hinge agrees in both, the animal inhabiting the pectens is very different from that of the oyster; for which reason Linnaeus has divided the genus into sections. The pectines by some are esteemed as delicious a food as the oyster. They differ very materially in a variety of circumstances. The pectens, as we have already observed, fail on the surface of the water; and besides, if they are attacked by a foe, they let down the membrane which nature has provided them for a sail, and drop to the bottom. "Behold (says Barbut) the splendor of the pectines, which rival the glowing colours of the papilionaceous tribe, as numerous as they are beautiful, flirting from place to place, and may well be called the papillones of the ocean. What superior qualities does not the pectine enjoy above the ostrea edulis, which, constantly confined to its native bed, seems wholly destined to afford food to other creatures, not having any means of defence, but its shelly castle, which is frequently attacked and stormed by its numerous enemies? This creature is not only useful to man as a dainty food, but the shell being le- vigated into a subtle powder, is employed as an absorbent in heart-burns and other like complaints arising from acidities in the first passages; the hollow shells are generally made choice of, as containing more than the thinner flat ones, of the fine white earth, in proportion to the outer rough coat, which last is found to be considerably impregnated with sea-salt."

The grand mark of distinction between the pectens and oyster seems to be the locomotive faculty. It was long supposed, that the oyster possessed no power of motion, that it always remained in the place in which nature or accident had placed it, and that its life differed little from that of vegetables. Experience, however, has taught us to reject these premature conclusions. We shall here lay before our readers at length, though perhaps a little out of its place, what Abbé Dicquemare has observed with respect to this circumstance, the conclusions of whose remarks we have given in another place. See Animal Motion, p. 411. col. 2.

"Passing one day (says the Abbé) along the seashore, I observed an oyster lying in a shallow place, and ejecting with considerable force a quantity of water. It immediately occurred to me, that, if this happened at a sufficient depth, the resistance of the water would have forced the oyster from its place. To be satisfied of this, I took several middle-sized oysters with a light shell, and placed them on a smooth horizontal surface, in a sufficient quantity of pure sea-water. Some hours elapsed, and the night came on before any thing remarkable appeared; but next day I found one of the oysters in a place and situation different from that in which I had left it; and as nothing could have discomposed it, I could not doubt but that it had moved by its own powers. I continued, however, to attend my charge; but, as if they meant to conceal their secret, the oysters always operated in my absence. At last, as I was exploring the coast of Lower Normandy, I perceived in an oyster-bed one of them changing place pretty quickly. On my return, therefore, to Havre, I made new dispositions to discover the means by which the motions of oysters are performed, and I succeeded. This animal ejects the water by that part of the shell which is diametrically opposite to the hinge; it can also throw it out at the sides, at each extremity of the hinge, or even from the whole opening at once. For this purpose, it can vary the action of its internal mechanism; but the soft parts are not the only organs that perform this function; in certain cases the shells assist in forcing out the water.

"When an oyster thus suddenly, forcibly, and repeatedly, squirts forth a quantity of water, it repulses those of its enemies that endeavour to infest themselves within the shells while they are open; but this is effectual only against its weakest foes; for there are some so formidable by their strength or their address, that a great number of oysters perish in this way. The animal, therefore, endeavours with all its force to repel them; it does more, it retreats backwards, or starts aside in a lateral direction. All of them, however, are not placed in circumstances favourable for these motions. They are often situated in the crevices of rocks, between stones, or among other oysters, some in sand, and some in mud; so that their strength, or powers of motion, are exerted in vain. It is probable, however, that they have the faculty of operating their own relief from these circumstances, and that they may be accidentally assisted by other bodies. It must, however, be acknowledged, that the means of relief cannot be numerous or considerable in such as are attached to other oysters, to a body heavier than themselves, or to a rock; but such situations are the most uncommon in the oyster-beds that I am acquainted with on the French coasts in the Channel. Perhaps, indeed, a very angular or heavy shell may be sufficient to render an oyster immovable. This is undoubtedly the case with such of them as have been obliged by worms, or other more formidable enemies, so to increase their shells as to make them thick and unwieldy. But we do not know whether these animals, in unfavourable circumstances, may not be able to supply those manoeuvres that I have mentioned by others that I have not as yet been able to observe. An oyster that has never been attached, may fix itself by any part of the margin of either of its valves, and that margin will become the middle, or nearly so, if the oyster is young. I would not be surprised, that oysters, which have been fixed to a rock from the beginning, should be able to detach themselves. I have seen them operate upon their shells in so many different ways, and with such admirable contrivance, when those shells have been pierced by their enemies (among whom I must be ranked), that I do not think it at all impossible for them to quit the place to which they are attached. It will easily be imagined how delicate and difficult such observations and experiments must be, considering the sensibility of the animal, the delicacy of its organs, the transparency of the matter that forms the layers of its shells, the opacity of the shells themselves, the vicissitudes of the sea, and the seasons, &c. But it was of use to show, that, contrary to the opinion generally entertained by the learned as well as by fishermen, oysters are endowed with a locomotive faculty, and by what means that faculty is exerted. I must add, that those which first showed me these motions, were brought from the coasts of Bretagne, put into a bed at La Hogue, then at Courseulles, whence they were carried to Havre; and that, as all these transportation were made in a dry carriage, the oysters could not be in perfect vigour. It was necessary also to show, that these animals have much more sensation and more industry than is generally attributed to them.

"It is not often that a sagacious observer of nature is seduced from his object by the pride of appearing above it, or the desire of generalization. To think of grasping the whole of nature, when we are unable to consider in the whole the first and most interesting of her kingdoms, is a vain illusion. Yet some have endeavoured to confound the kingdoms, while they have taken the liberty of dividing the highest of them into beings differently animalized. Under the pretence of having a better idea of it, they lopped off all the extremities; that is to say, they rid themselves of everything they were not well acquainted with, or that threw difficulties in their way. This, to be sure, was very convenient, but very unsuitable to the proceeding of an enlarged mind, and very unfit to inform us with regard to the economy of nature. The organization of the oyster, though very different from that..." Pectoral with which we are best acquainted, may be comprehended under our considerations of the animal economy in general. Those authors are not so enlightened as they imagine, who represent the oyster as an animal deprived of sensation, as an intermediate being between animals and vegetables, as a plant, and even in some respects as inferior to a plant. It is thus that the oyster has been made a foundation for many an absurd hypothesis with respect to the nature of animals. But let us quit the consideration of these fantastic pictures, and attend to the original.

"The oyster is conscious of its existence, and conscious also that something exists exterior to itself. It chooses, it rejects; it varies its operations with judgment, according to circumstances; it defends itself by means adequate and complicated; it repairs its losses; and it can be made to change its habits. Oysters newly taken from places which the sea had never left, inconsiderately open their shells, lose the water they contain, and die in a few days: but those that have been taken from the same place, and thrown into beds or reservoirs from which the sea occasionally retires, where they are incommodeed by the rays of the sun, or by the cold, or where they are exposed to the injuries of man, learn to keep themselves close when they are abandoned by the water, and live a much longer time." See Ostrea.