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moned as a witness against him: Apuleius, having done so, was accused of magic; a very strong proof against him being his employment of fishermen to procure Aplysia for the purpose of satisfying his curiosity by a careful examination of them. The poison itself was reputed subtle and peculiar in its action, killing very slowly and deliberately, not absolutely destroying life until after as many days as the sea-hare itself had lived after having been taken out of the sea. Its employment, however, was not safe to those who used it, for it betrayed its presence by too many peculiar symptoms in the human sufferer, who gave out an odor from his body similar to that attributed to the mollusk. Even in these enlightened days, fishermen all over the world-Britons and Italians, Malays and Polynesians, devoutly believe in the evil qualities of this sea-slug. How strange that so prevalent, so far-extending a superstition should be absolutely groundless! All modern naturalists of reputation who have examined the sea-hare about its poisonaus qualities, have agreed to pronounce it guiltless of the crimes laid to its charge. This bé te noire of fishermen and compilers is a pretty, harmless, quiet, inoffensive creature, crawling among the rainbow-colored seaweeds that fringe most rocky shores just beneath low-water mark; sporting with Doris and Antiopa, and other graceful nymphs of the briny waters, who in these prosaic times reveal themselves to men in the diminished shapes of delicately-robed mollusks. The Aplysia might stand as the representative of a thousand similar vulgar errors. Erroneous fancies about the qualities of animals and plants are elements of popular belief. Often, as in the instance we have just been recording, it is almost impossible to trace even the shadow of a foundation for the popular notion. Fictions of this kind have an astonishing vitality, and survive in defiance of general intellectual progress. They are changeable and pertinacious as some of those surprising creatures which the microscope brings within the compass of our ocular ken-now contracted into an almost inconceivable point, now swelling into sizeable masses; round one moment, square the next; shooting out limbs at pleasure, and retracting them as rapidly; capable of disappearing for a season, and on the return of favoring conditions, becoming as vivacious and astonishing as before. So very few persons have acquired in the course of their education even the rudiments of natural history science, that it is almost impossible

to argue with, still more to convince them, about the erroneousness of their baseless superstition respecting animals and plants. In nine cases out of ten they appeal to the experience either of themselves, or of some equally ill-informed friends, on whose judgment they place confidence. It is not merely the uneducated or partially educated who sin in this foolish way; scholars and mathematicians are as prone to be confident in their capacity to pronounce judgment upon matters requiring a peculiar training and study ere they can be correctly observed, as peasants and fishermen. The evil will not be remedied until training in the methods of observation, and instruction in the elements of natural history, form part of the necessary education of youth. None but a naturalist can conceive the astounding folly of the prevailing ignorance about even the commonest biological phenomena.

There is, however, a mollusk, the worker of ten times more mischief to mankind than ever the sea-hare was accused of doing, savagely as that poor innocent has been slandered. The shipworm or teredo is a bivalve shell-fish, which, as if in revenge for the unceasing war waged by mankind against its near relative the oyster, seems to have registered a vow to extinguish the vitality of as many human beings as lies within its power. That power, though exercised by an insignificant shell-fish, is a prodigious one, for ever since mankind turned attention to nautical affairs and went to sea in ships, the teredo has unceasingly endeavored, unfortunately with too much. success, to sink their marine conveyances. Nor have vessels alone been the object of its attacks, for many a goodly landing pier has it riddled into shreds, not to speak of bolder attempts, such as the endeavor to swamp Holland by destroying the piles of her embankments.

The shipworm is the only mollusk that has ever succeeded in frightening politicians, and more than once it has alarmed them effectively.

A century and a quarter ago, indeed, all Europe believed that the United Provinces were doomed to destruction, and that the teredo was sent by the Deity to pull down the growing arrogance of the Hollanders. "Quantum nobis injicere terrorem valuit,' wrote Sellius, a politician who suddenly became a zoologist, and a good one too, under the influence of the general alarm, "quum primum nostros nefario ausu muros conscenderet, exilis bestiola! quanta fuit omnium, quamque universalis consternatio! quantus

pavor! quem nec homo homini, qui sibi maxime alias ab invicem timent, incutere similem, nec armatissimi hostium imminentes exercitus excitare majorem quirent." In our own country, although we undergo no danger of being suddenly submerged, as our Dutch. neighbors might be, we have suffered seriously in our dockyards and harbors by the operations of the shipworm, to which the soundest and hardest oak offers no impediment. As a defence against it, the underwater portion of woodwork in dockyards has been studded with broad-headed iron nails. Like most mollusks, the teredo, though fixed when adult, is free in its young state, and consequently enabled to migrate and attach itself wherever mischief can be done by it. Thus ships at sea are attacked, and no wood has yet been found capable of defying its efforts. Even teak and sissoo woods, hard as they are, dissolve before it with rapidity; and though the chemical process of kyanizing timber successfully defeats the ravages of time, it fails before the voracity of the teredo. By a remarkable instinct, the shipworm tunnels in the direction of the grain of the wood, whatever be its position, and thus succeeds in its purpose with destructive rapidity. The tube with which it lines its bore is sometimes nearly two feet and a half in length; it is not always straight, for if the creature meets an impediment sufficiently hard to defy its power, it takes a circuitous course, and thus gets round the obstacle. In like manner it avoids any interference with its fellow-shipworms, winding round them in such a way, that at length a piece of wood attacked by many teredos becomes transformed into a knot of calcareous tubes. The tube is not the true shell of this dreaded mollusk. That body is to be sought for at its innermost extremity. It consists of two very small curved valves, united at their beaks, and beautifully sculptured on their surfaces. The pipe or tube is a limewalled shaft, intended to keep up a communication between the animal and the watery element necessary for its existence, and to protect the soft body and long fleshy siphons of the creature. How the cavity in which it lives is excavated is still a matter of discussion among naturalists. There are many shell-fish endowed with the instinct to burrow into wood or clay, or even hard stone; and it is not yet certain whether they do so by mechanical or by chemical agencies, or by a combination of the actions of an auger and a solvent. Many sea snails, as well as bivalve shell-fish, have the power to perforate solid substances; and some of

the predacious kinds exercise this faculty to the detriment of their brother shell-fish by boring through their outer coverings, and extracting the juices of their bodies by means of long soft extensile trunks. There is reason to believe that this operation is effected by the aid of the siliceous teeth which stud their long ribbon-shaped tongues. These microscopic teeth are beautiful objects, exhibiting regular and constant shapes; so constant, indeed, that by mere inspection of a fragment of the tongue of a sea or land snail, the naturalist can pronounce to a certainty upon the affinities of the creature to which it belonged. Even its particular genus may be verified; and in a few years (for this kind of research is as yet novel and only commenced) probably its very species may be thus determined. These teeth are arranged in transverse rows upon the tongue. From an ordinary individual of the common limpet, a tongue two inches in length may be extracted, armed with no fewer than 150 or more bands of denticles, twelve in each row, so that in all it may possess nearly 2000 teeth. The limpet uses this elaborate organ as a rasp with which to reduce to small particles the substance of the sea-weeds upon which it feeds. In some of our common garden slugs as many as 20,000 teeth may be counted. Wonderful, indeed, is this complication of minute organisms!

Throughout nature apparent evils are compensated by unnoticed benefits. Destructive as the shipworm unquestionably is, nevertheless we could ill dispense with its services. Though a devastator of ships and piers, it is also a protector of both, for were the fragments of wreck and masses of stray timber that would choke harbors and clog the waves, permitted to remain undestroyed, the loss of life and injuries to property that would result would soon far exceed all the damages done and dangers caused by the teredo. This active shell-fish is one of the police of Neptune: a scavenger and clearer of the sea. It attacks every stray mass of floating or sunken timber with which it comes into contact, and soon reduces it to harmlessness and dust. For one ship sunk by it a hundred are really saved; and whilst we deprecate the mischief and distress of which it has been the unconscious cause, we are bound to acknowledge that without its operations, there would be infinitely more treasure buried in the abysses of the deep, and venturous mariners doomed to watery graves.

Shell-fish had once the reputation of being among the dullest, most inert, and stupid of

traordinary position, being arranged in shining | rows along the borders of the creature's cloak or mantle, starring the edges immediately within the margin of the shell and in front of the tender and filamentous gills; as if a man should bear a row of eyes instead of buttons upon his coat and vest, a place for them by no means inappropriate or inconvenient, if, like acallops, he were deprived of a head. The sense of smell is clearly possessed by slugs and snails, for fresh food, as long ago observed by Swammerdam, attracts them towards it. In what particular organ lay the faculty was, however, a matter of dispute; and Cuvier went so far as to surmise that in these animals the whole surface of the skin might be susceptible of perceiving odors, as if the mollusks were just so many animated and independent noses. But Owen has of late years shown that in the nautilus, at least, there is a distinct and specially organized smelling organ; and the indefatigable naturalists who do so much honor to their town of Newcastle,* have demonstrated, among sea-slugs much lower in the molluscous series, elaborately-constructed organs of smell, the true significance of which had previously been undiscovered.

Strange as it may seem, next to touch, the sense most generally distributed among shellfish is that of hearing. The ear or hearing

* Mr. Alder, Mr. Albany Hancock, and Dr. Em

bleton, all of Newcastle-on-Tyne. The researches of these gentlemen among the mollusks are among the most elaborate and admirable that have been conducted during the present century. The beautiful monograph of the British Nudibranchiata, published by the Ray Society, a union of naturalists deserving of general subscription and encouragement,

is the work of the two former naturalists.

organ is of very curious structure. It consists of one or more hyaline capsules, each supplied with its special auditory nerve. In this little cavity or sac are contained sparry crystalline corpuscles, composed of carbonate of lime, varying in number in different species of mollusks. These minute bodies are in continual motion, vibrating backwards and forwards, rotating on their own axes, or rushing with violent motion towards the centre of their prison, whence they are as violently repelled. A careful tracing of the relations of this curious mechanism to the well-developed and unquestionable organs of hearing in higher animals, leaves no doubt respecting their functions. Indeed, it would seem that among much lower types of animal life than shell-fish belong to, the sense of hearing is manifested by similar rudimentary organs. Our knowledge of the extension of the senses among the mollusca is of very recent date; yet inquiries into this matter have not been undertaken of late years only. These creatures have been favorite subjects for the inquisitions of anatomists for two centuries back. But nature seems to dole out her secrets gradually and in portions, so that we may have due time to meditate upon the significance of each fact, and be more and more impressed with the imperfections of human science, and the necessity for continued and persevering research. "In these discoveries," writes Dr. Johnston, “you have a lively example of the nicety of anatomical researches in our times. In my student days it was questioned whether any mollusks besides the cuttles had eyes; and it was agreed on all hands that they were earless and surd." Behold the change a few years have made in our knowledge of this branch of physiology!"

SLEEP. There is no better description, given of the approach of sleep, than that in one of Leigh Hunt's papers in the Indicator: "It is a delicious moment, certainly, that of being well nestled in bed, and feeling that you shall drop gently to sleep. The good is come, not past; the limbs have been just tired enough to render the remaining in one posture delightful; the labor of the day is done. A gentle

failure of the perceptions comes creeping over; the spirit of consciousness disengages itself more, and with slow and hushing degrees, like a mother detaching her hand from that of her sleeping child; the mind seems to have a balmy lid closing over it, like the eye; 'tis more closing-'tis closed. The mysterious spirit has gone to take its airy rounds."