The genera of the Crustacea are so extremely numerous, and the knowledge we possess of their natural history is so scanty, being generally confined to their form and colour, that we shall limit ourselves to a description of some of the best known and most useful species.

The Crabs are a very numerous tribe, and contain many singular species, as far as regards their form, which assumes an endless variety of curious shapes, sometimes elegantly decorated with the most brilliant colours; this more particularly applies to those which are found in the seas of hot climates.

The singular little animal represented in the preceding page, was placed by naturalists among the Crustacea, and considered a perfect animal of a distinct species; it was named Zoea. Mr. Thomson, the experienced naturalist we have already noticed, was the first to discover the real nature of this little creature. We cannot do better than to introduce the subject by the following observations of the author of this discovery, showing the reason so little is known respecting these inhabitants of the deep.

“The sea (which is the habitation of the greater part of the Crustacea) to the casual observer offers nothing but an immense body of water, here and there presenting a solitary whale, or a vagrant troop of some of the smaller cetaceous animals; the appearance of a fish of almost any other kind in the track of a vessel over a vast expanse of the open ocean, is regarded, even by the mariner, as a kind of phenomenon, and creates an interest not to be appreciated by those who have not engaged in distant voyages. The fathomless parts of the ocean certainly do not offer the same profusion of inhabitants with the shores of islands and continents, or those parts where the bottom is within reach of the sounding-line, or where the surface is interspersed with fields of Sargosa[6]. On due examination, however, we shall not fail to find it everywhere peopled by a considerable variety of animals, either of small size, or possessed of such a degree of translucency as to render them invisible, or scarcely perceptible, even when on or near to its surface; that it should possess its share of the organized beings which we see spread over every other part of the surface of our globe, is a conclusion we might arrive at indirectly, from the consideration of oceanic fishes and birds being observed in those parts of the ocean most distant from the land, and the provident care of the Deity, which we invariably witness throughout the domain of nature, to furnish food for all, even the meanest of his creatures; the more minute and invisible inmates of the sea, then, must constitute the food of oceanic fishes and birds.

“Few of these marine animals, except some of the larger and most conspicuous, have as yet been observed, so that the investigation of them holds out a promise of a rich harvest to the naturalist, and a vast field of exploration, replete with novelty and interest; to accomplish this, however, he must use the greatest diligence, seizing every opportunity, when the way of a ship does not exceed three or four miles per hour, to throw out astern a small towing-net of gauze, bunting, or other tolerably close material, occasionally drawing it up, and turning it inside out into a glass vessel of sea-water, to ascertain what captures have been made. When a ship goes at a greater rate, and in stormy weather, a net of this kind may be appended to the spout of one of the sea-water pumps, and examined three or four times a day, or oftener, according to circumstances.”

Although naturalists were decided in calling the Zoea a crustaceous animal, they were still far from agreeing as to the place in the system it ought to occupy, for the different species were so unlike each other: but it will be no longer a matter of surprise, when it is known, that this singular creature is not a perfect animal, but merely the larva, or imperfect state of the Common Crab. This fact is perfectly new, and interesting in a double point of view, not only proving their real nature, but also that the Crustacea are not, as described in most systems, animals undergoing no metamorphosis, and on that account to be separated from the insects, but that they do undergo a metamorphosis, and that of a most wonderful nature.

It was in the Spring of 1822 that Mr. Thomson first met with ZoeÆ, in the harbour of Cove, and that in considerable abundance; the year following, at the same season, one of considerable size occurred; this was considered a fit object for experiment, and was carefully supplied with fresh sea-water, from May 14th to June 15th, when it died in the act of changing its skin. That portion of its new form which it had been able to disengage was sufficient to show that it bore a great resemblance to the division of the Crustacea, in which the crabs and lobsters are placed. “This proof,” says the author, “might be considered incomplete, if I had not had the good fortune to succeed in hatching the ova of the Common Crab, during the month of June, which presented exactly the appearance of the Zoea taurus.”

The Common Crab, Cancer major, is so well-known, that any description of its appearance would be useless.

One singular part of the history of these creatures is, the power that is possessed by them, of changing their shell once in every year; this power is providentially bestowed upon them, to enable them to increase in size, a thing that would otherwise be utterly impossible, from the peculiar nature of the hard coat in which they are enclosed.

The Crab, in order to prepare for the extraordinary change it is about to undergo, when shifting its shell, chooses a close and well-secured retreat, in the cavities of rocks, or under great stones, where it creeps in and remains during the operation. The time of the year when this occurs is about the beginning of the Summer, at which time their food is in plenty, and their strength and vigour in the highest perfection. But soon all their activity ceases; they are seen forsaking the open parts of the deep, and seeking some retired situation among the rocks, or some outlet where they may remain in safety from the attacks of their enemies. For some days before their change, the animal discontinues its usual voraciousness; it is no longer seen laboriously harrowing up the sand at the bottom, or fighting with others of its kind, or hunting its prey; it lies torpid and motionless, as if in anxious expectation of the approaching change. Just before casting its shell, it throws itself upon its back, strikes its claws against each other, and every limb seems to tremble; its feelers are agitated, and the whole body is in violent motion; it then swells itself in an unusual manner, and at last the shell is seen beginning to divide at its junctures, particularly at those of the belly, where it was before seemingly united. It also seems turned inside out; and its stomach comes away with its shell. After this, by the same operation, it disengages itself of its claws, which burst at the joints; the animal, with a tremulous motion, casting them off, as a man would kick off a boot that was too big for him.

Thus, in a short time, this wonderful creature finds itself at liberty; but in so weak and enfeebled a state that it continues for several hours motionless. Indeed, so violent and painful is the operation, that many of them die under it; and those which survive, are in such a weakly condition for some time, that they neither take food, nor venture from their retreats. Immediately after this change, they have not only the softness, but the timidity of a worm. Every animal of the deep is then a powerful enemy, which they can neither escape nor oppose; and this, in fact, is the time when the dog-fish, the cod, and the ray, devour them by thousands. But this state of weakness continues for a very short time; the animal, in less than two days, is seen to have the skin that covers its body almost as hard as before; its appetite appears to increase; and, strange to behold! the first object, it is said, that tempts its gluttony, is its own stomach, which it was lately disengaged from. This it devours with great eagerness. In about forty-eight hours, in proportion to the animal’s strength, the new shell is perfectly formed, and as hard as that which was but just thrown aside. Previous to the time of moulting or changing their skin, a flat chalky stone is found on each side of the stomach; this is believed to form a store of earthy matter for the renewal of the shell. These stones, popularly known as crabs’ eyes, were long highly esteemed for their medicinal properties, but in reality are not superior to so much chalk.

When completely equipped in its new dress, the dimensions of the old shell being compared with those of the new, it will be found the creature has increased in size nearly one-third, and it appears wonderful how the old shell could have contained it.

Many of the cold-blooded animals have the power of reproducing a limb, or a portion of one, if by any accident it has been lost. This faculty of reproduction is possessed by the Crab in great perfection; but it has also a surprising power in itself, voluntarily to break off its own legs and claws. It seems this takes place when any serious injury, by bruising, has happened to any of its members. After it has received the hurt it bleeds, and gives signs of pain, by moving the wounded limb from side to side, but afterwards holds it quite still, in a direct and natural position, without touching any part of its body or its other legs with it. Then, on a sudden, with a gentle crack, the wounded part of the leg drops off at the next joint to the one injured; this appears to be more easily done with respect to the smaller legs, than in the case of an injury occurring to those which bear the pincers.

When the leg has dropped off, a mucus, or jelly, is discharged on the remaining part of the joint next the body, which, as a natural styptic, instantly stops the bleeding; this gradually hardens and grows callous, becoming a new leg in miniature, which at every change of the creature’s shell increases rapidly in size.

Crabs are naturally very quarrelsome, and with their claws fight and kill each other; and if by chance any of their limbs should be so bruised, as to have taken away from the creature the power of breaking off its claws, the protecting jelly is not produced, and the animal bleeds to death. An experiment was made to give some idea of the tenacious disposition of this creature, by obliging a Crab, with one of its great claws, to lay hold of one of its smaller ones; the silly creature did not distinguish that itself was the aggressor, but exerted its strength, and soon cracked the shell of its own small leg, which bled freely; but feeling itself wounded it succeeded in breaking off its limb in the usual manner,—still, however, holding fast for a length of time the part of the wounded leg which had come away.

The curious shuffling walk of the Crab is well known, but it does not, as it is said, walk exactly backwards.

The Land Crab, (Gecarcinus ruricola.)

Although nearly all the Crab tribe are inhabitants of the water, there is a species found in the West Indies, a native of the Bahama Islands, whose habits are unlike those of the rest of its class, and highly curious in themselves.

Land Crabs do not, like most other crustaceous animals, live near salt water, but take up their abode for the greatest part of the year in holes in the ground, hollow trunks of trees, and other places of the same description, and inhabit the mountainous districts of the islands, many miles from the sea-shore; but, although they make these places their usual haunt, it is necessary for them, once a year, to repair to the sea, for the purpose of depositing their spawn. They prepare for their annual migration about the month of April or May, and, having mustered in immense numbers, the procession sets forward, with all the regularity of an army, under the guidance of an experienced commander.

Their destination being the sea, they instinctively move in a direct line to the nearest coast; no obstacle which they can possibly surmount will induce them to turn from their course; for if even a house stands in their way, they endeavour to scale its walls, in which they sometimes succeed; and should a window remain open, they are not unlikely to direct their march over the bed of some heedless sleeper. If, however, a large river crosses their track, they continue to follow its course without attempting to cross it.

It is said, that they are commonly divided into three battalions, of which the first consists of the strongest and boldest males, who, like pioneers, march forward to clear the route. They are often obliged to halt for want of rain, and go into the most convenient encampment till the weather changes. The main body consists of females, who never leave the mountains till the rain has set in for some time; they then descend in regular order, formed into columns of the breadth of fifty paces, and three miles in length, and so close that they almost cover the ground. Three or four days after this, the rear-guard follows, a straggling undisciplined tribe, consisting of males and females, but neither so robust nor vigorous as the former parties. The night is their chief time of proceeding. When terrified, they march back in a confused manner, holding up their nippers and clattering them loudly, to intimidate their enemies. Their general food consists of vegetables; but if any of their companions should become maimed, and unable to proceed, they are greedily devoured by the rest.

After a march of two, and sometimes three months, in this manner, they arrive at their destined spot on the sea-coast; they immediately enter the water, and after the waves have washed over them several times, retire to holes in the rocks, and other hiding-places, where they remain until the period of spawning. They then once more seek the water, and, shaking off their eggs, leave them to the chance of being hatched, or devoured by tribes of hungry fish, who have already repaired to the spot in countless shoals, in expectation of their annual treat. The eggs that escape are hatched under the sand; and, soon after, millions at a time of the little Crabs are seen quitting the shore, and slowly travelling up to the mountains. The old ones, however, are not so active to return: they have become so feeble and lean, that they can hardly crawl about. Most of them, therefore, are obliged to continue in the flat parts of the country till they recover; making holes in the earth, into which they creep, and cover themselves up with leaves and dirt; here they throw off their old shells, and continue almost without motion for about six days, during which time they become so fat, as to be considered delicious food. In about six weeks, the new shell has become tolerably hard, and the creatures may be seen slowly returning to their mountain-haunts. In some of the sugar-islands, it is said they form no inconsiderable portion of the food of the negroes, who are extremely dexterous in their mode of seizing them, so as to avoid their nippers.

The Hermit, or Soldier Crab,
(Pagurus bernhardus.)

This singular species of Crab has obtained its name from its habit of remaining, as it were, secluded, in any empty shell, or hole of a rock, it may fancy.

The hinder part of its body, particularly the tail, being constantly secure from injury, has its covering reduced to almost a membranous state, while the tail, which assists the other species in swimming, is almost obliterated; but in those which have chosen a shell for their hermitage, some hook-like appendages are observed, which enable them to maintain a secure hold of their borrowed dwelling. When the body has grown too large for the shell occupied by the animal, it is obliged to seek another of a larger size. The numerous combats they enter into when seeking a new dwelling, have caused this animal to receive the additional name of the Soldier Crab.

“The Soldier when about to seek a new habitation, is still seen,” says an amusing writer, “in its own shell, which it appears to have considerably outgrown; for a part of the naked body is seen at the mouth of it, which the habitation is too small to hide. A shell, therefore, is to be found, large enough to cover the whole body; and yet not so large as to be unmanageable and unwieldy. To answer both these ends is no easy matter, nor the attainment of a slight inquiry. The little Soldier is seen busily parading the shore, along that line of pebbles and shells that is formed by the extremest wave; still, however, dragging its old incommodious habitation at its tail, unwilling to part with one shell, even though a troublesome appendage, till it can find another more convenient. It is seen stopping at one shell, turning it and passing it by, going on to another, contemplating that for a while, and then slipping its tail from its old habitation, to try on a new. This, also, is found to be inconvenient; and it quickly returns to its old shell again. In this manner, it frequently changes, till at last it finds one light, roomy, and commodious: to this it adheres, though the shell be sometimes so large as to hide the body of the animal, claws and all.”

Yet it is not till after many trials, and many combats also, that the Soldier is thus completely equipped; for there is often a contest between two of them for some well-looking favourite shell, for which they are rivals. They both endeavour to take possession; they strike with their claws; they bite each other, till the weakest is obliged to yield, by giving up the object of dispute. It is then that the victor takes possession, and parades in his new conquest three or four times back and forward, upon the strand, before his envious antagonist.

When this animal is taken, it sends forth a feeble cry, endeavouring to seize the enemy with its nippers; which if it fasten upon, it will sooner die than quit the grasp. The wound is very painful, and not easily cured.

On the English coasts the Hermit Crab is generally found in the shell of the whelk, or when of a small size in that of the periwinkle; they not unfrequently, however, remain in some cranny of a rock, or under the protecting cover formed by a group of pebbles, in the interstices of which they hide themselves.

The ancients were well acquainted with the Soldier Crab, as is evident from the following translation of the lines of one of their poets:

The Lobster, (Astacus europÆa.)

The well-known and delicious shell-fish, the Lobster, is found in great abundance in all the northern parts of Europe. The north of Scotland is famous for the Lobster, but it is still more plentiful on the coast of Norway. The crab is more frequently found in shallow water, but the Lobster prefers those spots where the water is of considerable depth. The methods of taking Lobsters are various,—the most usual is by means of what are called Lobster-pots; these are a sort of trap, formed of twigs, and baited with garbage; they are made like a wire mouse-trap, so that when the Lobsters get in there is no possibility of returning. These pots are fastened to a cord, and sunk in the sea, their place being marked by a buoy. Another method of taking them is by means of a kind of bag-net, baited with animal substances. This fishery is only carried on in the night. They are brought in vast quantities to the London market from the Orkneys and from the Norway coast.

Lobsters are much alarmed at the noise of thunder, or any other sudden shock; the consequence of which is, that in their fright, they frequently cast their claws. This also often happens when the poor creatures are thrown into the boiling-pot. As these animals frequent clear water, their habits have been more noticed than those of the crab. Their mode of feeding is sufficiently curious. In general, the pincers of one of the large claws are furnished with knobs, while the other large claw is more like a saw on its edge; holding, then, its food in the knobbed claw, it dexterously pulls it to pieces with the other. Their movements in the water are exceedingly graceful and lively, and they are capable of darting forward to a considerable distance with the rapidity of the flight of a bird. Their colour, when in their native element, is not black as might be imagined, but a beautiful deep blue.

A whimsical idea of the horror Lobsters are said to have of pigs, seems to have prevailed in some parts of the Continent. It is said that in Brandenburgh, where the fishery is very abundant, the wagoners who transport them by land are obliged to keep watch during the night, to prevent swine from passing the wagon, for if one only was to go by, they say, not a single Lobster would be alive in the morning!

The River Cray-Fish, (Potamobius fluviatilis.)

The fresh-water Cray-fish very much resembles the lobster in appearance, but is considerably broader in its proportions. It is commonly found in the tributary streams of large rivers, inhabiting the banks, in which it burrows, and feeding on any animal substance that may happen to come in its way.

The Cray-fish is taken in various ways, sometimes by the hand, which is thrust into the holes in which they burrow. Another method is thus described:—

Procure a dozen little rods, about five feet in length, and the thickness of the thumb,—split them at the smallest end, and by way of bait, place a frog, or a piece of putrid flesh in the cleft; take then the rods by their thickest end, and hold the bait at the entrance of the little holes where you suspect your prey to be; if they are there, they will generally come out to seize the bait. As soon as you perceive them, hold a small landing-net underneath, and raise the bait suddenly, and the Cray-fish will either be brought up along with the bait, or will fall back into the net.

Another method noticed, consists in first burying a dead cat, or a hare, in a dunghill, for eight days, and then placing it in the midst of a bush of tangled thorns and brambles, which is thrown into the water, in the place frequented by the Cray-fish. After it has remained there a few hours it may be drawn up, when the shell-fish will be found partaking of their delicate fare, and the tangled bush will effectually prevent their escape.

The Phosphorescent Shrimp.

The luminous appearance of the ocean at night is a fact well-known to all who have been a voyage by sea; and it has been ascertained, that the causes of this beautiful phenomenon are the phosphorescent properties which are possessed by many of the smaller inhabitants of the deep. Among these, the little animal, figured above, is very frequently met with.

The light of this creature, which is very brilliant, appears to issue from every part of the body; but in another crustaceous animal, found by Captain Tuckey, in the Gulf of Guinea, the luminous property resided in the brain, which, when the animal was at rest, resembled a most brilliant amethyst, about the size of a large pinhead; from this there started, when it moved, flashes of a brilliant silvery light.

The author we have lately quoted, says,—

“Meditating upon this subject, I think it not improbable, that the Deity, who has done nothing in vain, and whose omniscience extends to every epoch, foreseeing that man would invent the means of tempting the trackless ocean, and explore the most distant regions of our planet, has given it as one means of rendering his nights less gloomy, and of diminishing the number of his dangers; especially, if we consider that this luminosity is seen only in the night-season,—is vivid in proportion to the darkness, disappearing even before the feeble light of the moon,—and also that it increases with the agitation of the sea, so that, during the prevalence of storms, it greatly diminishes the dense gloom which at such times is often impenetrable to the moon, and the stars, throws such a light upon the ship and rigging as to enable sailors to execute their allotted tasks with certainty, and at all times points out to the cautious mariner the lurking danger of sunken rocks, shoals, and unknown coasts, by the phosphorescent, or snowy appearance which it gives to the breakers, so as to render them visible at a considerable distance.”

The Opossum Shrimp, (Mysis chamÆleon.)

This small species of Shrimp, although it has much the same outward appearance as the common shrimp, except that it is considerably smaller, is, when duly examined, one of the most singularly-formed creatures of the class to which it belongs. It is found in tolerable abundance along the British coasts, but the northern seas literally swarm with them; there, in spite of their small size, they are destined to become the food of the stupendous whale, whose enormous mouth encloses myriads at a time.

The Opossum Shrimp belongs to a group of crustaceous animals which have been called fissipeds, (split-feet,) on account of each of their feet being divided nearly throughout its whole length; the inner limb being constructed for progression and the seizing of their prey, and the outer for swimming and giving that motion to the water which is essential to the organs of breathing, which are, as it were, wrapped round the base of each limb, and fully exposed to the action of the element. In the other Crustacea, which they most nearly approach, such as shrimps, prawns, &c., there is a single row of five feet on each side: but the genus we are now describing possesses as many as four rows of feet, each containing eight, so that in all, the number of feet amounts to as many as thirty-two,—sixteen adapted for swimming, and sixteen for seizing their prey. In consequence of this organization, the Shrimps seek their food in the sands at the bottom, while the present genus frequent the surface.

The most singular portion of their formation, and that to which they are indebted for a name, is a kind of pouch which the female possesses, fixed beneath the body, and formed of two concave pieces of shell; this pouch, which is very capacious, considering the size of the animal, is destined to receive the eggs, which are deposited in it, enveloped in a kind of jelly-like substance, most probably forming the food of the young when first hatched. As fast as the young assume the lengthened form of the perfect animals, they are found to arrange themselves in this pouch closely and regularly side by side, with their heads towards the breast of the mother. After this manner they lie closely compacted together, and present a perfectly symmetrical arrangement, easily observed from the translucency of the valves of the pouch, and the large size and blackness of their eyes. The males of the Opossum Shrimp are not so numerous as the females, and are without the singular pouch we have described.

We have already noticed the fact of these Shrimps being the food of the Greenland whale, in the northern seas, but in these climates they serve as food for herrings.

It is in looking closely into the structure of these little animals that we see the perfection of the Divine Artist. Nature’s greater productions appear coarse indeed to these elaborate and highly-finished master-pieces, and in using more and more powerful magnifiers we still continue to bring new parts and touches into view. If, for instance, after observing one of their members with the naked eye, which has informed us that the part we have been examining is composed but of one piece, we employ a magnifying glass with a low power, the same part appears jointed, or composed of several pieces articulated together. Employing a higher magnifier, it appears fringed with long hairs, which, on further scrutiny, seem to be themselves fringed with hairs still more minute; many of these minute parts also, are evidently jointed, and perform sensible motions. But what idea can we form of the various muscles which put these parts in movement, of the nerves which actuate them, and the vessels which supply them with the nourishment necessary for growth and support, and which we know, from comparison with other creatures, they must possess!

The Opossum Shrimps, we have seen, are the prey of the larger inhabitants of the deep; but they, in their turn, destroy others that are smaller than themselves,—seizing upon every animal substance they are able to manage that comes within their reach, and, if placed in a vessel of sea-water by themselves, devouring each other.

The species represented in the engraving has been called the Mysis chamÆleon, from its colour varying according to the substances on which it feeds, through all the gradations of gray, black, brown, and pink.

ORDER CRUSTACEA HETEROBRANCHIÆ.

(Crustacea with Organs of Breathing variously
placed, never concealed.)

The Crustacea which form this order differ much more from each other than those which are arranged in the last order, and consequently we find among them some very singular in their outward formation. Few of the species appear to be used as food by mankind, but they constitute a great portion of the nourishment of fishes and other inhabitants of the water. They are at times used by fishermen as bait. Many of them are very minute, and form most excellent objects for the microscope. They have been divided into several sections, according to their outward form; but as so little is known of their habits, we shall confine ourselves to a description of some of the best known.

The Spotted Squill, (Squilla maculata.)

The Squill seems to form a connecting link between the last and present order. It is the only genus of the heterobranchial Crustacea in which the eyes are placed on footstalks; the head, instead of being distinct, appears in a great measure drawn into the corslet. It has been called the Sea Mantis, from its bearing some resemblance to an insect of that name, on account of the singularly-formed hooks with which two of its foot-jaws are armed.

The species shown in the engraving is found in the Indian Seas; it is the largest of the genus.

The shell with which these creatures are covered has very little consistence, more resembling hardened skin than shell. They frequent the sandy bottom of the sea.

There is a small species which is found in fresh water, in which the young, after the eggs are hatched, remain for some time in shelter under the plates with which the body of the mother is covered.

The Common Cloportus, (Cloportus ascellus.)

This animal is very common upon old walls and under stones. It is somewhat like the wood-louse, but more flat; it is essentially a dweller on the land, but it cannot exist except in damp places, where the moisture is sufficient to keep its branchiÆ pliable; it belongs to a group of small Crustacea known by the name Oniscus. Some, as we see in the present instance, frequent the land, but the greater portion inhabit the water.

Among those which inhabit the latter element, there is a minute species which is very injurious to timber. It excavates a cylindrical hole for its dwelling, and increases in number so rapidly, that in a few years timber which is covered with water is rendered useless. The temporary wood-work used during the time the Bell-Rock Lighthouse was in the course of erection, was destroyed, to a great extent, by this little creature. When the wood had been under water for three years, beams ten inches square were reduced to seven inches; at the rate of one inch a year. Another species, Cymothoa, attaches itself to the backs of different species of fishes, living upon the juices of their body.

A crustaceous animal nearly allied to this last is described in the fifth volume of the American Philosophical Transactions; it is accompanied by engravings which we have copied, but the animal is not drawn with sufficient accuracy to be referable to any particular species; by this account it appears that, instead of attaching itself to the body of the fish, the parasite makes safe its lodgement on the roof of the mouth. The author thus describes it.

“Among the fish that at this early season of the year (February) resort to the waters of York River, in Virginia, the Alewife, the Oldwife, called also the Bay Alewife, arrives in very considerable shoals, and in some seasons their number is almost incredible. They are fully of the size of a large herring, and are principally distinguished from the herring by a bay or red spot, above the gill-fin. They are, when caught from March to May, full-roed and fat, and at least as good a fish for the table as the herring.

“In this season, each of these Alewifes carries in her mouth an insect about two inches long, hanging with its back downwards, and firmly holding itself by its fourteen legs to the palate.

“It is with difficulty it can be separated, and never, perhaps, without injury to the jaws of the fish. The fishermen, therefore, consider the insect as essential to the life of the fish; for when it is taken out, and the fish is again thrown into the water, he is incapable of swimming, and soon dies. I endeavoured in numerous instances to preserve both the insect and the fish from injury, but was always obliged, either to destroy the one or injure the other.

“I have sometimes succeeded in taking out the insect in a brisk and lively state. As soon as he was set free from my grasp, he immediately scrambled nimbly back into the mouth of the fish and resumed his position. In every instance he was disgustingly corpulent and unpleasant to handle, and it seemed that, whether he had obtained his post by force or favour; whether he be a traveller or constant resident, or what else may be his business where he is found, he certainly fares sumptuously every day.

“The fish whose mouth he inhabits, comes about the same time with the shad into the rivers of Virginia from the ocean, and continues to travel upwards from the beginning of March to the middle of May. As long as they are caught on their passage up the river, they are found fat and fall of roe. Every fish which I saw had the Oniscus in his mouth, and I was assured, not only by the more ignorant fishermen, but by a very intelligent man who came down now and then to divert himself with fishing, that in forty years’ observation he had never seen a Bay Alewife without the louse.”

The Oniscus itself, as the author states, is not without its enemies, many of them being caught with two or three leeches attached to their body, and adhering so closely that their removal cost them their heads.

The Molucca Crab, (Polyphemus gigas.)

Why the singular creature here represented should have the name Polyphemus given to it, is hard to guess. Polyphemus, as every schoolboy knows, was the fabled giant overcome by Ulysses, who is represented as having one eye in the centre of his forehead; whereas, this creature has two eyes and one horn. It is interesting from its being so nearly allied to many very minute species.

The Polyphemus sometimes reaches the length of two feet; there are but two species, which only differ from each other in the shape of their buckler. That we have represented is found in the Indian Ocean, and has been called the Molucca Crab.

The tail, or rather the horn, of the Polyphemus, is greatly dreaded by the fishermen, from the idea that its wound is venomous. The natives employ it to point their arrows, and as they are in the habit of poisoning the points of these weapons, it is most likely from this circumstance that the idea we have noticed originated, for there is no other ground for the belief.

During the night-time they lie half out of the water, and are then very easily taken, as they appear to take but little notice of anything until their danger becomes imminent.

It is but a small portion of their flesh that is considered good for food, but the eggs, which are very numerous, are reckoned a delicacy.

These Crabs are in the habit of leaving the water and walking to a considerable distance over the wet sands,—but if incommoded by the sun, they hurry back as fast as they are able to their native element. When walking, none of their legs are visible. Most authors say that, if this Crab is laid on its back, it must inevitably perish, unless the waters return in time, but one observer asserts that it has the power of righting itself with the assistance of its tail.

The Crab-like Limulus, (Limulus cancriformis.)

The Limuli are found in deep ditches of fresh water, marshes, &c.; they are frequently met with congregated together in great numbers; their principal food in the Spring appears to be tadpoles.

“This genus,” says Lamarck, “is almost isolated among the group in which it is placed. Its body is covered with a great horny buckler, very thin, and made of a single piece, of a roundish oval form. The head is confounded with the trunk, and the antennÆ are very short. They possess three eyes, two in front, and one, very small, further back. Their legs are very numerous,—the two in front, much the largest, spread out in the form of oars, and furnished at their extremity with silky articulated bristles.”

The Water Flea, (Cyclops quadricornis.)

There are as many as twelve known species of the Water Flea. That represented in the engraving is extremely common, and forms a most interesting object for the microscope. We have availed ourselves of Mr. Pritchard’s popular description of this curious creature.

“The Author of Nature, to whom all things are alike easy of execution, as if intending to teach man a lesson of humility, and that no part of creation, however minute, is beneath his consideration, has conferred on these animals, that are barely perceptible to our unassisted vision, more elegance and variety of form, more richness in their colouring, and more beauty and exquisite finishing, than on the whale or the elephant, which mainly excite our admiration, by the magnitude of the mass of living matter they present to us.

“These little crustaceous animals may be found at all seasons of the year, near the surface of the water; they are, however, most abundant in July and August. I have collected great numbers of them on a warm day in the latter month, with a small cloth net, immersing it about an inch below the surface. They are mostly colourless in ponds covered with herbage, but in small collections of rain water, on a loamy soil, are of a fine rich colour.

“The body of this creature is covered with crustaceous or shelly plates, which overlap each other, and admit both of a lateral and vertical motion between them. Their ends do not meet on the side, but have sufficient space between them for the insertion and play of the organs of respiration. The rostrum, or beak, is short and pointed: it is a prolongation of the first segment which forms the head. A little above the beak, a single eye is imbedded beneath the shell, of a dark crimson colour, nearly approaching to blackness. The true form of this organ it is difficult to determine. Mr. Baker gives it the shape of two kidney-beans placed parallel to each other, and united at their lowest extremities. When viewed laterally, it appears round, while in some other positions it is square.”

The eggs are curiously placed in two bags, presenting an appearance similar to clusters of grapes, and of considerable magnitude, compared with the size of the animal. These egg-bags are seen in the engraving, (which represents a female,) projecting from each side of the hinder portion of the shell. The centre of each egg is of a deep opaque colour, which in some specimens is green, in others red.

The young of the Cyclops, when first excluded from the egg, are extremely minute, and so different from the mother, that MÜller has described them as forming two distinct genera.

The Small Water Flea, (Cyclops minutus.)

This species of the Water Flea differs from the last, in having its body divided into a greater number of segments; it is also much smaller; it is equally active with that last described, but its form renders it more graceful in its motions. “These little creatures,” says Mr. Pritchard, “seem to possess great discernment and cunning; for, if approached, they remain motionless on the plant on which they reside, in the apparent hope that they may be overlooked; but when a fit opportunity occurs, they suddenly bend the body, and spring away with a kind of vaulting leap.”

Cyclops minutus, much magnified.