Chapter II: Part 2

We are among the olive-coated stones at the verge of the far-receded tide, among which the springs from the cliffs having broken out from various points in the shingle beach, are making for themselves tortuous channels on their way to the deserting sea. Their water, originally fresh of course, has, by the time it arrives here, become so brackish by washing the salt stones and sea-weeds, that the sand-hoppers and worms which inhabit the hollows under the stones are bathed in it with impunity, though, in general, immersion in fresh water is fatal to marine animals. Great tufts of bladder wrack and other _Fuci_ spring from the lower stones, and now lie flaccid about, awaiting the returning tide to erect them and wave their leathery leaves to and fro. Broad fronds of _Ulva_, too, like tissue paper of the tenderest green, irregularly crumpled and waved, and nibbled and gnawed into thousands of holes, lie crisp and tempting; and tufts of a darker, duller green, and others of purple-brown, and others again of rosy crimson, stud these rough stones, and vary their ruggedness with elegance and beauty; a beauty, however, far more appreciable, and far more worthy of admiration, if we could look upon it when the flowing tide creeps up, with its calm water clear as crystal, and covers the many-hued parterre, softening and displaying the graceful outlines and the brilliant colours. Then, too, those tiny creatures would be seen agilely swimming from weed to weed, or lithely twining among the fronds, which now we have to search for in their recluse hiding-places under these rocks.

Selecting a stone which experience teaches us is a likely one---and only experience can teach this, though in general I may say that the heaviest and flattest beneath, those which appear to have been long undisturbed, and especially those which, instead of being imbedded in the soil, rest on other stones in such a partial way that there is room for free ingress and egress to minute creatures beneath, and which have a broad surface to which they may cling in congenial darkness, are the most promising---selecting, I say, such a stone, we place both hands beneath one side, and heave with all our might to turn it bodily over. We must be careful, for many of these stones are so beset with the small shells of _Serpula triquetra_, that they cannot be handled with impunity. This is a worm which makes a tubular pipe for its defence, of hard shell, adhering to the rock throughout its length; the tube enlarges a little as it grows, and its most recent extremity, which is brilliantly white and clean, is defended by the projecting extremity of a ridge which runs along the back of the shell, the point of this ridge forming a very sharp needle-like prickle, which, as we apply our hands beneath the stone to lift, terribly cuts the fingers. On some stones we find hundreds of these treacherous shells, set as thickly as they can stand, and covering large patches; on others they are scattered, and some are quite free from them. In an aquarium the little worms protrude their breathing fans very constantly, and are pretty, though not conspicuous objects, being varied with bright blue, grey, and white. Pretty as they are, however, the collector wishes them further a hundred times during his collecting, for, in such an expedition as this, he is fortunate indeed if he come home without half of his fingers gashed with deep incisions, smarting from the sea-water, and all the slower to heal from the skin of the finger-tips being worn to thinness in handling the stones.

But these are trifles; the fortune of war; amply compensated by the joy of victory, when we succeed in capturing some rare or lovely creature, to be displayed in triumph within the glass walls of a prison. Such an one is this beauty, which is lurking in an angle of the block we have just overturned. It needs a sharp eye to detect it; for we see no beauty yet, nothing but a little lump of whitish jelly, dappled with orange-yellow, not bigger than the half of a split pea, clinging close to the stone. It requires some care to get it up without crushing; the end of a toothpick, or a penknife, or a bit of stick cut to a point, must be inserted under it; thus we lift it, and drop it into the ready phial of clear water. It opens instantly, sprawling even before it reaches the bottom, where it at once begins to crawl, and we detect in our prize the lovely little Triope.[16]

THE TRIOPE.

As it swiftly glides up the glass, we see that it has an oblong body of a pellucid white hue, curiously beset with finger-like appendages. There is a row of some half-dozen or so fringing the front of the head; and down a line on each side of the body, margining the mantle, there is a row of larger ones, and all these are tipped with the richest orange colour. Just behind the frontal points there are two club-shaped organs, which start up out of holes, the sides of which form sheaths for them, into which they can be withdrawn at the will of the animal. These organs carry a number of narrow plates set parallel to each other, diagonally pointing backwards and downwards. Doubtless, this structure is intended to augment the sensitive powers of these curious organs, which are understood to be the tentacles.

Then, in the middle line of the back, but placed a little nearer the tail than the head, there is an orifice, which is the vent; remarkable because the breathing organs are arranged partly around it. There are three tiny leaves cut like the fronds of a fern, which stand up over the orifice, and are endowed with the power of absorbing for the purposes of respiration the oxygen of the air commingled in the water.

But here is an animal which possesses all these peculiarities of structure, displayed on a much larger scale. It is a fine specimen of the Sea Lemon,[17] which we oftener find clinging to the sides of perpendicular rocks, or beneath projecting ledges, than on the undersides of stones. This fellow is two and a half inches long, and an inch and a quarter or more broad; but I have met with individuals much larger than he. Its back is rounded, and its outline generally reminds one of the half of a lemon cut longitudinally. The resemblance is heightened, too, by the round warts with which the whole surface is studded, and by the colour, a yellow more or less pure, often, however, clouded, as in this instance, with purple, by which its beauty is much enhanced.

PLATE 4.

P. H. GOSSE, _del._ LEIGHTON, BROS.

SEA LEMON. CROWNED EOLIS. SPAWN OF BOTH.
]

The mantle, in this Doris, reaches down to the foot on all sides, and covers the head, and is not furnished with any appendages. The tentacles, which are plated, as in the Triope, pierce through the mantle, and are sheathed; the gill plumes are large and ample feather-like organs, eight in number, forming a complete circle round the orifice, in the manner of a beautiful expanded flower.

As the Doris crawls along, it now and then lifts and puckers the edge of the mantle, and displays its under surface and that of the foot, which are of a rich orange-scarlet hue.

THE CROWNED EOLIS.

But we have turned a stone beneath which lurk several specimens of a much lovelier creature yet. I see by the gleams of crimson and azure which shine out from it, that it must be the Crowned Eolis.[18] It looked a little heap of fibrous semi-pellucid flesh when out of water, and, like the Triope, must be immersed to display its beauties. Now in the phial of water, how elegant it is! Its body is long and slender, tapering away to an almost imperceptible point behind, of a clear translucent white. The head forms two long smooth taper tentacles, which wave hither and thither as the creature gracefully glides along; and besides these it has two other tentacles, distinguished as the dorsal pair, resembling, in their position and in their structure, those of the Doris and Triope, but not sheathed.

The chief glory of this exquisite animal, however, is in its breathing organs. These consist of clusters of finger-shaped papillæ, set transversely across the back, in about six rows, with the middle line of the back free. Each of these papillæ is pellucid, with a central core of the richest crimson, while a very brilliant flush of steel blue is reflected from the surface, and the tip is opaque white. The combination of these hues has a most charming effect.

You would scarcely suppose such lovely creatures were fierce and carnivorous; but they are the most determined enemies of the Sea Anemones. This beautiful Eolis I have often seen assaulting an Anemone, ferociously tearing away its tentacles, or gnawing great holes in its side, and, when touched, stiffening and erecting all its brilliant papillæ, as the porcupine does its quills.

All these creatures are Mollusca very closely allied to the Cowry and the Trochus which we lately examined, but destitute of a shell. The exposure of the breathing organs is a distinguishing character (these being more commonly, in the order, concealed in a cavity), whence they are called _Nudibranchiata_, or Naked-gilled Mollusks.

At this season, wherever we find the animals themselves, we may with confidence expect to find their spawn. This is deposited in masses, which possess characteristic forms. Thus this roll, which looks as if you had made a thin ribbon of paste, half an inch wide, and rolled it into a loose scroll of two or three turns, and then affixed it by its edge to the under side of a stone, is the spawn-mass of the Sea Lemon. And here is a much more elegant scroll, of which the constituent is a slender thread, twisted into a frilled or figure-8 form, as it goes on to make the spire.[19] This has been laid by the beautiful Crowned Eolis. If you examine either of these masses with a lens, you will see that it is composed of a vast multitude of white eggs, suspended in a clear jelly, in which they are arranged in transverse rows, giving the opaque appearance to what would else be colourless and transparent.

EGGS OF NUDIBRANCHS.

The eggs, watched day by day under a good microscopic power, as they advance towards maturity, present a most interesting object of study. The yolk, which at first nearly fills the egg-shell, soon becomes a little elongated, with one end diagonally truncated, or, as it were, cut off obliquely; the truncated end then becomes two-lobed, “each lobe exhibiting an imperfect spiral, and having its margin ciliated. The now animated being is seen to rotate within its prison. Shortly the lobes enlarge, and a fleshy process, the rudimentary foot, is observed to develop itself a little behind them, on the medial line; a shell closely investing the inferior portion of the embryo, the lobes and rudimentary foot being uppermost. The shell rapidly increases, and assumes a nautiloid form; afterwards the foot displays, attached to its posterior surface, a circular operculum, which is opposed to the mouth of the shell. The lobes now expand into two large, flattened, ovate appendages, with very long vibratile cilia around the margins; and the larvæ are at length mature. The whole mass of spawn now presents the utmost animation. Hundreds of these busy atoms are seen, each within its transparent, membranous cell, rotating with great agility and ceaseless perseverance, the cilia all the while vigorously vibrating on the margins of the outstretched lobes. The membranous chorion [or transparent egg-shell], which by this time has become enlarged, ultimately gives way, no longer able to resist the perpetual struggle within; and the liberated larva, wending its way through the shattered shreds of the general envelope, boldly trusts itself to the open trackless water, where, doubtless, thousands and tens of thousands perish ere they find a fitting resting-place, some being swept away by resistless currents, others falling a prey to ever-watchful and innumerable enemies.

“When the larva is at rest, the oral lobes are pulled back into the shell, and the foot being drawn down, brings along with it the operculum, which closes the orifice. But when in action, the whole of these parts project beyond the opening of the shell, the foot lying back against the spire; and the oral lobes inclining forward, their cilia commence to vibrate, and the larva, with the mouth of the shell upwards, moves through the water with lively action, sinking or rising, or advancing onwards at its pleasure.”[20]

SPAWN OF EOLIS.

The fecundity of these mollusca is immense. An _Eolis papillosa_ of moderate size in one of my aquaria, deposited successively nine strings of spawn between March 20th and May 24th. The strings were exactly alike in length and arrangement; each comprised about 105 convolutions, and each convolution 200 eggs, while each egg contained on an average two embryos. Thus the astonishing number of 378,000 embryos proceeded from this one animal in about two months.

Step by step we have crept along the beach, turning stones as we went, till we are come to the great masses of sandstone rock. Here are the Purples[21] by hundreds, with their strong massive shells, some of them pure white, which, however, becomes dingy with age, some banded with brown, and some, especially the young and half-grown ones, painted with a dull but soft purplish hue. The older specimens have the inner surface of the lip tinged with a rich rosy purple. This tint on the shell we may receive as the advertisement of the colorific property that resides within, a sort of sign-board to tell us that this is the “genuine” purple-shell. And there is little doubt that it is one of those enumerated by Pliny, as used by the ancients for obtaining the renowned dye of Tyre: though the principal, and that which yielded the richest hue, was probably the _Murex trunculus_, a common Mediterranean shell, which does not extend to our shores.

PLATE 5.

P. H. GOSSE, _del._ LEIGHTON, BROS.

LIMPET. PURPLE. SLIT-LIMPET.
]

My readers are, I dare say, familiar with the pretty myth which professes to embody the discovery of the purple dye. The Tyrian Hercules was one day walking with his sweetheart along the shore, followed by her lap-dog, when the playful animal seized a shell that had just been washed up on the beach. Its lips were presently dyed with a gorgeous purple tint, which was traceable to a juice that was pressed out of the shell-fish. The lady was charmed with the colour, and longed to have a dress of it; and, as wishes under such circumstances are laws, the enamoured hero set himself to gratify her, and soon succeeded in extracting and applying the dye, which afterwards became so famous. I have elsewhere[22] recorded my own experiments on the stain yielded by the _Purpura_ before us, with the remarkable changes through which it passes before the sunlight fully brings out the colour. The use of cochineal makes us independent of molluscan dyes, and the matter is merely one of antiquarian interest, or a question of zoological chemistry.

EGGS OF DOG-WINKLE.

Perhaps you may be more interested in the development of the Dog-winkle. Under the ledges of rocks we find in abundance groups of little yellow bodies, resembling ninepins in shape, set on their ends in close contact with each other, and varying in numbers from three or four to a hundred or upwards in a group. Some of them are tinged with purple at the tips; and while sometimes you find them closed, and full of a yellow creamy substance, at others they are open at the top, and empty.

These are the egg-capsules of this mollusk, and some very unusual circumstances connected with the birth of the progeny, and their development within these cases, have been discovered by Dr. Carpenter.[23] Each capsule contains 500 or 600 globules that cannot be distinguished from each other at first; but only twelve to thirty of these are developed into young animals, though their united bulk ultimately equals that of the whole mass. The greater number of these globules are not real eggs, but only “yolk-spherules,” destined to afford nutriment to the true embryos, which greedily swallow them, after certain changes have taken place, and increase rapidly in bulk. It is curious, however, that they do not advance in development during this absorption of nutriment, but are, so to speak, arrested until a great augmentation of size is thus attained; then they quickly acquire the form of little free-swimming nautiloids, closely like those of the Doris and Eolis, a form which indeed is common to the early stages of all the known higher mollusca, however various may be their adult conditions.

LIMPET.

Here are the familiar Limpets, too: let us look at _them_ awhile.[24] They are not generally very attractive in appearance, the shell being coarse and rubbed, especially in the larger specimens; and in an aquarium they do not live long, and are so inert as to afford no amusement even while they survive. Yet we occasionally find examples prettily coloured; and there are facts in their economy which make them worthy of a few moments’ notice.

If you look carefully over the rocks, especially when these are of a somewhat soft nature, as the slates and shales, you will find oval depressions, sometimes but just discernible, at other times sunk to the depth of an eighth of an inch, corresponding in outline to the shell of a Limpet; and in many instances you will actually see a Limpet imbedded in such a pit, which it accurately fills. Strange as it may seem, it has been ascertained that these cavities are formed by the animals, which make them their ordinary resting-places, wandering away from them nightly to feed, and returning to them to rest early in the morning.

The force with which a Limpet adheres to the rock is very great, especially when it has had warning of assault, and has had time to put out its muscular strength. Réaumur found that a weight of twenty-eight or thirty pounds was required to overcome this adhesive force. His experiments seem to prove, however, that its power is mainly owing, not to muscular energy, nor to the production of a vacuum in the manner of a sucker. If an adhering Limpet were cut quite through perpendicularly, shell and animal, the two parts maintained their hold with unabated force, although of course a vacuum, if there had been one, would have been destroyed by the incision. The power is said to reside in a very strong glue, a very viscid secretion, deposited at the will of the animal. “If, having detached a _Patella_,” says Dr. Johnston, “the finger be applied to the foot of the animal, or to the spot on which it rested, the finger will be held there by a very sensible resistance, although no glue is perceptible. And it is remarkable that if the spot be now moistened with a little water, or if the base of the animal be cut, and the water contained in it allowed to flow over the spot, no further adhesion will occur on the application of the finger: the glue has been dissolved. It is nature’s solvent, by which the animal loosens its own connexion with the rock. When the storm rages, or when an enemy is abroad, it glues itself firmly to its rest; but when the danger has passed, to free itself from this forced constraint, a little water is pressed from the foot, the cement is weakened, and it is at liberty to raise itself and be at large. The fluid of cementation, as well as the watery solvent, is secreted in an infinity of miliary glands with which the foot is, as it were, shagreened; and as the Limpet cannot supply the secretion as fast as this can be exhausted, you may destroy the animal’s capacity of fixation by detaching it forcibly two or three times in succession.”

THE GILLS.

If we remove one of these Limpets from his selected area of rock,--which we may readily do, notwithstanding the strength of his cement, if we take him at unawares, and give him a smart sudden horizontal rap with a piece of wood, or a moderated blow with a hammer,--we shall obtain a view of a structure well worth looking at. The animal is essentially like a Trochus or a Purple inhabiting a conical shell; only in this case the cone is low and simple, whereas in the others it is tall and slender, and rolled into a spire. One of the most curious peculiarities in the Limpet is its gill or breathing organ. This, we perceive, completely encircles the animal, forming a ring interrupted only at one point. It lies in the fold between the mantle and the foot, commencing on the left side of the neck, and passing quite round the body, parallel with the edge of the shell, in front of the head, till it terminates close to the point where it began. It is a long cord closely beset with tiny leaflets, and thus forming a continual plume. Each leaflet, conical in outline, is permeated with blood-vessels, and clothed with minute _cilia_, whose constant vibrations cause the circumambient water ever to play over the surface of these organs in ceaseless currents, bringing fresh supplies of oxygen to be respired; and this is absorbed by the blood through the thin membrane by which they are protected.

There is a very pretty little shell, not uncommon in deep water off these coasts, but rarely found by the shore collector, though it does occasionally venture to peep at daylight at the verge of extreme low-tide. It is the Slit Limpet,[25] which by the older naturalists was placed in close alliance with the Limpets proper, as if a member of the same family. They were, however, deceived by paying too exclusive attention to the form of the shell, which is a cone, somewhat rounded, and nearly simple, the summit being slightly turned over in a backward direction. The margin of the shell is delicately notched, the points being the extremities of the radiating ridges; for the entire surface is covered with reticulations, one series of alternate furrows and ridges proceeding from the summit to the margin, and another series crossing these at right angles, running round the shell parallel with the margin. The animal has its sides ornamented with short fleshy processes, and possesses two symmetrical gill-plumes, one on each side. It is rather attractive in appearance, but I cannot tell you anything of its manners; for though I have kept specimens in the aquarium, they are so habitually sluggish, and so reluctant to allow one a peep beneath the edge of the jealous shell, that I could learn nothing about their ways;--if indeed they have any.

PHOLAS HOLES.

Another curious form closely related to this is the Keyhole Limpet,[26] whose shell is of a long oval outline, of a lower cone, reticulated, like the Slit Limpet, but pierced at the summit with a double hole, or rather a perforation apparently made of two holes broken into one, something like a keyhole. This orifice, like the slit in the former case, is for the discharge of the effete water taken in in breathing.

See! here is the soft red sandstone lying in great beds, pierced through and through with smooth round holes, just as if bored with a carpenter’s auger, big enough to admit a man’s thumb. What agency has been in operation to effect these perforations? Let us try to discover.

A few good blows with the stout hammer on the chisel-head serve to split off a great slice of the coarse red sandstone. The holes run through its substance, but they are all empty, or filled only with the black fœtid mud which the sea has deposited in their cavities. Yes; these are too superficial; they are all deserted; the stone lies too high above low-water mark: we must seek a lower level. Try here; where the lowest spring-tide only just leaves the rock bare. Ha! now we have uncovered the operators. Here lie, snugly ensconced within the tubular perforations, great mollusca, with ample ivory-like shells, which yet cannot half contain the whiter flesh of their ampler bodies, and the long stout yellow siphons that project from one extremity, reaching far up the hole towards the surface of the rock.[27]

We lift one from its cavity, all helpless and unresisting, yet manifesting its indignation at the untimely disturbance by successive spasmodic contractions of these rough yellow siphons, each accompanied with a forcible _jet d’eau_, a polite squirt of sea-water into our face; while, at each contraction in length, the base swells out, till the compressed valves of the sharp shell threaten to pierce through its substance.

PLATE 6.

P. H. GOSSE, _del._ LEIGHTON, BROS.

RED-NOSE. FINGER-PHOLAS.
]

HYPOTHESES OF THEIR FORMATION.

Strange as it seems, these animals have bored these holes in the stone; and they are capable of boring in far harder rock than this; even in compact limestone. The actual mode in which this operation is performed long puzzled philosophers. Some maintained that the animal secreted an acid which had the power of dissolving not only various kinds of stone, but also wood, amber, wax, and other substances, in which the excavations are occasionally made. But it was hard to imagine a solvent of substances so various, and to know how the animals’ own shells were preserved from its action; while, confessedly, no such acid had ever been detected by the most careful tests.

Others maintained that the rough points which stud the shell enable it to serve as a rasp, which the animal, by rotating on its axis, uses to wear away the stone or other material; but it was difficult to understand how it was that the shell itself was not worn away in the abrasion.

Another zoologist, rejecting this hypothesis, maintained that the edges of the mantle and the short thick foot are the instruments employed; and that, though these fleshy organs seem little fitted for such work, they are really endowed with the requisite power in the shape of crystals of flint which are deposited thickly in their substance. Strange to say, however, other accurate observers fail to detect these siliceous crystals, and therefore reject the hypothesis.

Another suggested that the stone was removed in invisible particles by the constant action of currents in the water, produced by vibratile cilia seated on the soft parts of the animal; but this supposition was found untenable on examination.

Actual observation in the aquarium has proved that the second hypothesis is the true one. M. Cailliaud in France and Mr. Robertson in England have demonstrated that the Pholas uses its shell as a rasp, wearing away the stone with the asperities with which the anterior parts of the valves are furnished. Between these gentlemen a somewhat hot contention was maintained for the honour of priority in this valuable discovery. M. Cailliaud himself used the valves of the dead shell, and imitating the natural conditions as well as he could, actually bored an imitative hole, by making them rotate. Mr. Robertson, at Brighton, exhibited to the public living Pholades in the act of boring in masses of chalk. He described it as “a living combination of three instruments, viz., a hydraulic apparatus, a rasp, and a syringe.” But the first and last of these powers can be considered only as accessory to the removing of the detritus out of the way, when once the hole was bored, the _rasp_ being the real power. If you examine these living shells, you will see that the fore part, where the foot protrudes, is set with stony points arranged in transverse and longitudinal rows, the former being the result of elevated ridges radiating from the hinge, the latter that of the edges of successive growths of the shell. These points have the most accurate resemblance to those set on a steel rasp in a blacksmith’s shop. It is interesting to know that the shell is preserved from being itself prematurely worn away by the fact, that it is composed of arragonite, a substance much harder than those in which the Pholas burrows. Yet we see by the specimens before us that such a destructive action does in time take place, for some of these have the rasping points much more worn than others, many of the older ones being nearly smooth.

The animal turns in its burrow from side to side when at work, adhering to the interior by the foot, and therefore only partially rotating to and fro. The substance is abraded in the form of fine powder, which is periodically ejected from the mouth of the hole by the contraction of the branchial siphon; a good deal of the more impalpable portions being deposited by the current as it proceeds, and lodging as a soft mud between the valves and the stone. Mr. Hudson,[28] who watched some Pholades at work in a tide-pool in the chalk, observed the periodic ejection of the cloud of chalk-powder, and noticed the heaps of the same material deposited around the mouth of each burrow. The discharges were made with no regularity as to time. Mrs. Merrifield[29] records a curious fact. “A lady, watching the operations of some Pholades which were at work in a basin of sea-water, perceived that two of them were boring at such an angle that their tunnels would meet. Curious to ascertain what they would do in this case, she continued her observations, and found that _the larger and stronger Pholas bored straight through the weaker one_, as if it had been merely a piece of chalk rock.”

Mr. Ross, of Rhyl, having a Pholas in his aquarium, prepared a piece of wood, by excavating a shallow cavity, about a quarter of an inch deep, in which he set the animal, whose shell was two inches long. “After a short time the animal attached its foot to the bottom of the hole and commenced swaying itself from side to side, until the hole was of sufficient depth to allow it to proceed in the following manner:--It inflated itself with water, apparently to its fullest extent, raising its shell upwards from the hole; then holding by its muscular foot, it drew its shell gradually down. This would have produced a perpendicular and very inefficient action, but for a wise provision of nature. The edges of the valves are not joined close together, but are connected by a membrane (extension of the mantle), and instead of being joined at the hinge (umbo) like ordinary bivalves, they possess an extra plate, attached to each valve of the shell, which is necessary for the following operation:--In boring, this mollusk, having dilated itself with water, draws down its shell within the hole, gradually closing the lower anterior edges until they almost touch. It then raises its shell upwards, gradually opening the lower anterior edges, and closing the upper, thus boring both upwards and downwards. The spines are placed in rows, like the teeth of a saw; those towards the lower part of the shell being sharp and pointed, while those above, being now useless, are not renewed.”[30]

RED-NOSES.

In this limestone cliff we shall find other borers, for you may see even at a considerable distance how holed and honeycombed its surface is; the cavities being so numerous, so close, and so irregular in their direction, that the whole face of the rock is fashioned into small sharp-edged shapeless points. Nor need we be long in finding the industrious masons who thus rough-point acres upon acres, nay miles upon miles, of limestone rock. Here in ten thousand orifices you discern little double-tipped knobs of crimson flesh, which, as soon as you disturb them, shoot at you a column of water and then disappear within their fortress, having exhausted their artillery. The fishermen know them well, and use them for bait, applying to them the familiar but expressive soubriquet of Red-noses.[31]

It is not so easy to get at these as at the Pholades, because of the superior hardness of the stone which they excavate. With the chisel, however, we need not fail of uncovering a few, especially as their burrows are but shallow. Here they are, half-a-dozen in a block as big as your fist. Ugly, uncouth, bemired, the valves not nearly containing the shapeless flesh, they are not particularly attractive creatures, maugre the brilliant hue of their blushing siphons. Like Mrs. Merrifield’s Pholas, these Saxicavæ habitually break into one another’s houses, as we see here, and even cut one another’s shells and bodies through and through most ruthlessly. They will live very well out of the rock, and may be kept a considerable time in the aquarium.

There is no doubt that the burrowing Mollusca are slowly but surely effecting changes in the configuration of rocky coasts, by destroying the rock. It is true their excavations extend but a few inches in depth; but then, as the force of the elements readily breaks down the thin partitions left standing, and discovers a new face, so the borers are continually renewing their attacks on this; and so in time the cliffs are worn away, while the debris of impalpable mud is deposited upon the shallows, entering into new combinations, and filling up estuaries and harbours.

FOOTNOTES:

[16] _Triopa clavigera._

[17] _Doris tuberculata_, which the reader will see figured in Plate IV., in the centre of the foreground.

[18] _Eolis coronata_, figured in the upper part of Plate IV., above the Sea Lemon.

[19] Both these are depicted in Plate IV. That on the right of the picture is the spawn of _Doris tuberculata_; that on the left is the spawn of _Eolis coronata_.

[20] Alder and Hancock (DORIS).

[21] _Purpura lapillus_, sometimes known as the Dog-winkle. Three individuals, representing the varieties of colour, are seen in the middle of Plate V., and a cluster of their egg-capsules in the lower left corner.

[22] See _Devonshire Coast_, p. 60.

[23] _Trans. Micr. Soc._ (Ser. II.), vol. iii. p. 17.

[24] _Patella vulgata_, represented by two examples in Plate V., at the left side of the picture.

[25] _Emarginula reticulata_, of which a figure appears in the right-hand corner of Plate V.

[26] _Fissurella reticulata._

[27] _Pholas dactylus_; the principal figure in Plate VI., represented as exposed in its burrow by the splitting off of a portion of the limestone rock.

[28] _Zoologist_, p. 7819.

[29] _Nat. Hist. of Brighton_, p. 185.

[30] _Zoologist_, p. 6541.

[31] _Saxicava rugosa_; represented by the smaller figure in Plate VI.

III.

MARCH.

Perhaps the most effective aid to the investigation of natural history which the present age has produced is the invention of the aquarium, and particularly its application to marine forms of life. Depending on that grand principle of organic chemistry, of world-wide prevalence, that the emanations from animals and vegetables are respectively essential to the continued life each of the other, it was discovered that the relative proportions of number and bulk in which organic beings of the two kinds could healthfully live together was easily determined; and since the fact that the creatures were inhabitants of water, whether fresh or salt, presented no exception to the universality of the law, they had but to be placed together in a suitable ratio, enclosed in a vessel containing water, and an aquarium was established. Improvements in the form of the vessel, in the mode of exposing the contents to observation, in the impact of the rays of light, in the arrangement of the interior, and other points of value, have indeed been progressively made; whereby the practical availability of the invention for the purposes of experimental natural history has been augmented; but some of us have found little difficulty, even from the very first announcement of the discovery, in maintaining the collections of sea-water, with their living plants and animals, unchanged from year’s end to year’s end. I may be perhaps excused for observing, that I have at present in use a large tank, full of marine creatures, in which the water has been unchanged for four years, and on which I look with peculiar interest, because it was the first tank ever made for private use. This very aquarium has afforded, and still affords the opportunity for the observation of many interesting details of the structure and habits of the lower forms of animal life, details which constitute the basis not only of my works on marine natural history already published, but of the present series of papers also. We collect the creatures, indeed, abroad, and there gather up some broad facts of interest concerning their modes of life; but it is at home, in the quiet of the study, with conveniences and aids to examination, experiment, and record at command, that they must be studied. The aquarium becomes in fact an apparatus, whereby we bring a portion of the sea, with its rocks, and weeds, and creatures, to the side of our study-table, and maintain it there.

USE OF THE AQUARIUM.

Thus an opportunity of close and valuable familiarity with sea-productions is open to multitudes who have never seen the broad expanse of ocean, nor searched its prolific shores; and facilities for extending the bounds of zoological science are everywhere enjoyed, which till lately were restricted to a very few naturalists, whose residences were situated on certain favourable spots upon the coast. Yet both modes of investigation are necessary. He who has never seen marine animals except in the confinement of an aquarium, cannot but be conscious of many chasms in his knowledge, which are filled up by him who is in the habit of collecting his own specimens in their proper haunts; and who, by finding them _in ferâ naturâ_, can, when he studies them at leisure in his tanks, make such allowances as are necessary for the variations in habit which may be dependent on the difference between their present artificial, and their original natural, conditions of existence.

While we rejoice then in tanks and vases of crystal water, filled with the lovely forms and brilliant hues of sea-weeds and sea-anemones, I invite my readers to accompany me on a few hours’ visit to the charming creatures at their own homes. The season is propitious; the sun has just passed the vernal equinox, and the genial warmth of spring is diffusing new life into the cold blood of the animals that dwell beneath the waters; the equinoctial storms that lately raged have blown themselves out, and are succeeded by a quietude whose effect is delightfully seen in yonder mirror-like ocean: it is the time of spring-tide; and the near approach of the hour of lowest water will afford us unusual facilities for finding species only to be invaded under such conditions.

Let us then scramble down to the beautiful Anstey’s Cove, along the steep path tangled with briers and ferns; where the swelling buds of the hawthorn and honeysuckle are already bursting, while the blackbird mellowly whistles in the fast-greening thicket, and the lark joyously greets the mounting sun above us. Yonder on the shingle lies a boat, newly painted in white and green, for the attraction of young ladies of maritime aspirations; she is hauled up high and dry; but the sinewy arms of honest Harry Bate, who hearing footsteps has come out of his little grotto under the rock to reconnoitre, will soon drag her down to the rippling waves, and, “for the small sum of a shilling an hour,” will pull us over the smooth and pond-like sea, whithersoever we may choose to direct him.

“Jump aboard, please, Sir! Jump in, ladies! jump in, little master!” And now, as we take our seats on the clean canvas cushions astern, the boat’s bottom scrapes along with a harsh grating noise over the white shingle-pebbles, and we are afloat.

SEA-CAVERN.

First to the caverns just outside yonder lofty point. The lowness of the tide will enable us to take the boat into them, and the calmness of the sea will preclude much danger of her striking the rocks; especially as watchful Bate will be on the alert, boat-hook in hand, to keep her clear. Now we lie in the gloom of the lofty arch, gently heaving and sinking and swaying on the slight swell, which, however smooth the surface, is always perceptible when you are in a boat among rocks, and which invests such an approach with a danger that a landsman does not at all appreciate. Yet the water, despite the swell, is glassy, and invites the gaze down into its crystalline depths, where the little fishes are playing and hovering over the dark weeds. The sides of the cavern rise around us in curved planes, washed smooth and slippery by the dashing of the waves of ages, and gradually merge into the massive angles and projections and groins of the broken roof, whence a tuft or two of what looks like samphire depends. But notice the colonies of the Smooth Anemone or Beadlet[32] clustered about the sides; many of them are adhering to the stone walls, several feet above the water. These have been left uncovered for hours, and are none the worse for it. They are closed, the many tentacles being concealed by the involution of the upper part of the body, so that they look like balls, or hemispheres, or semi-ovals of flesh; or like ripe fruits, so plump and succulent and glossy and high-coloured, that we are tempted to stretch forth the willing hand, to pluck and eat. Some are greengages, some Orleans plums, some magnum-bonums,--so various are their rich hues; but look beneath the water, and you see them not less numerous, but of quite another guise. These are all widely expanded; the tentacles are thrown out in an arch over the circumference, leaving a broad flat disk; just like a many-petalled flower of gorgeous hues: indeed, we may fancy that here we see the blossoms, and there the ripened fruit. Do not omit, however, to notice the beads of pearly blue that stud the margin all round, at the base of the over-arching tentacles. These have been supposed by some to be eyes; the suggestion, however, rests on no anatomical ground, and is, I am afraid, worthless; though I cannot tell you what purpose they do serve.

PLATE 7.

P. H. GOSSE, _del._ LEIGHTON, BROS.

SNOWY ANEMONE. DEAD-MAN’S FINGER. ROSY ANEMONE. LUCERNARIA. SMOOTH BEADLET. ]

TANGLE FORESTS.

Away! for I wish to explore another scene not less romantic than this, and which I know by experience to be much more prolific in strange and beautiful forms of life. Harry shall pull us round yonder low point, which bears the appellation of Hope’s Nose, calling on the way to look at some one of the inlets that lie between the long projecting points at the foot of Black Rock. Here the boat floats over dense forests of great brown sea-weeds, the _Laminariæ_, which lift their dark masses, and wave to and fro, with a majestic dignity. Here is the narrow crumpled blade of the Oarweed, of a rich yellow brown; and the wavy stem of the Furbelows springing from its hedgehog-like bladder; but chiefly is the forest composed of vast plants of the Tangle, whose broad deep-brown fronds of a substance like stout leather, French-polished, divide into many long straps, slide over each other, and flap to and fro in the heave of the sea. Yonder we see on the broadest part of a frond, just before it divides, what seems a flower, as large as a chrysanthemum, but of the liveliest pea-green hue, every long petal tipped with rosy pink. Hand over the boat-hook, and carefully lift the tangle to the surface. Now we have it fully in view. It is the green variety of the Opelet;[33] so called because it is scarcely capable of infolding the walls of the body over the disk and tentacles; these therefore remain habitually _open_, though the animal is at times much less expanded than at others. We now see it in its most charming condition; the short fawn-coloured column inflated, the mouth elevated on a strong cone in the centre of the wide saucer-shaped disk, and the numerous tentacles arranged in groups, as if several stems sprang from the same root, long, slender, very flexible, twisting about like the snaky locks of Medusa’s head, all of the most delicate light green, with a rich satin lustre, and all tipped with the richest crimson-lilac or light rose,--a most beautiful harmony of colours. The animal adheres by a broad base firmly to the disk of the tangle, and awaits, as it waves hither and thither, the approach of one of the little fishes that play heedlessly at bo-peep among the fronds. No sooner does one of them touch the far-stretching tentacles, than a virulent and penetrating poison shoots through its frame; its vigour is benumbed in an instant; it ceases to struggle; its powerful fins strike the water no more; others of the fatal tentacles enwrap themselves around it, and drag it towards the mouth, already protruding and expanding in expectation of the morsel; where it is in a few minutes engulfed, and soon digested in that capacious maw.

PLATE 9.

P. H. GOSSE, _del._ LEIGHTON, BROS.

GREEN OPELET. ORANGE-DISK ANEMONE.
]

It is not very uncommon for a single specimen of this species to become two by a perpendicular division. The whole process has been observed. A little notch first appears in the margin of the disk, which extends, cutting through the tentacles of that side, splitting the disk across, proceeding through the tentacles on the opposite side till it divides the margin there also. Meanwhile, it has advanced downward in an equal ratio, till it has reached the base; and at length there are two half-opelets still adhering in the closest proximity. Now, however, the two raw and open surfaces close up, and the bases glide gradually apart. A thick wall of flesh forms between the stomach and the wound, and new tentacles develop themselves on this. The two Opelets are complete.

RAISED BEACHES.

Half-an-hour’s vigorous pulling has doubled the long promontory of Hope’s Nose, a wilderness of stones, like what I suppose, from published descriptions, the foot of Mount Sinai to be, and brought us, between two raised beaches, into the pretty cove of Meadfoot, capped by elegant villas. These beaches, evidences of the lifting of the land, for they surely once stood, as beaches stand now, at the sea-level, are situate, the one on the main, the other on the Thatcher, a rocky islet some two hundred yards off shore. A few minutes more, and we are in a wild scene indeed. Isolated rocks stand up, in angular masses, upright columns, and sharp peaks, out of the sea, which is quite deep, even at lowest spring-tide. The coast itself too is rugged, precipitous, and in many spots quite perpendicular; one bold promontory, which runs out with a narrow knife-edge summit, is perforated by a natural archway of lofty elevation, of very striking aspect. It is distinctly visible for miles along the shores of Torbay, and is dignified with the name of London Bridge.

Here, then, is our fishing-ground to-day. Threading the slender passages between the perpendicular rocks, or creeping-in close under their overhanging landward sides, where no ray of the sun has ever penetrated, we hang on by the points and groins, and eagerly peer below. Into one lane our boatman hesitates to venture. It is but just wide enough to allow the boat to pass; indeed here and there she cannot without rubbing her gunwales; and if a stronger swell than usual were to roll-in from seaward while entangled, her side might be stove-in before she could be extricated. However, its gloom looks so tempting, and the water among the islets is so very smooth, that we succeed in persuading him, and we push and drag into the very midst of the watery alley. The rocks rise close on either hand like lofty walls, and descend as perpendicularly, deep and far down beneath our keel; as we can well see, for the water is of lustrous transparency.

LIFE ON SEA-ROCKS.

And what a sight is here! Hundreds of Anemones of many species are studding the walls almost as thick as they can be packed. Every tiny crevice, every hollow, every hole left by _Pholas_ or _Saxicava_ (and the rock is riddled and honeycombed by these burrowing mollusks), holds its little knob of plump flesh; some lolling out with a dewdrop hanging from the end; some just filling the cavity, and allowing the tips of the crowded tentacles to peep out as a speck of white, or of orange, or of rosy lilac, according to the species; and some retreated to the bottom of their stony fortress, to be detected only by the probing touch. Other forms too there are;--dead men’s fingers, white and yellow; worms, green and brown and grey, twining in and out, and grasping the sharp edges of the rock; tunicate mollusks, simple and compound; univalves and bivalves; sponges of all bright colours by hundreds:--what a maze, what a teeming world of life it is!

All this is at and above the level of the eye. Now let us bend over the boat’s gunwale, and gaze below, with our faces brought nearly to the surface of the sea. Here the sight is far more wonderful, and far more attractive; for here the life is seen in all its fullest activity, every creature performing its functions, and pursuing its instincts with the most single earnestness, self-contained, and altogether regardless of the myriad fellow-beings that surround it and press upon it, in this eager contest and struggle for maintained existence.

DEAD MAN’S FINGER.

A yard or two below the surface the eye is caught by a great oyster projecting from the vertical wall. It is a strange situation for an oyster to be in, but it shows how the infant young, in their free-swimming form, so different from their ultimate condition, may be carried by the aid of their own cilia, and the sea-currents, into the most improbable situations, and may there find circumstances congenial for permanent settlement.[34] Perhaps, however, its brown and rough shell would scarcely have attracted our notice, but for the rider that sits upon it. A specimen of the Dead-man’s finger,[35] of noble dimensions, has selected this shell as the seat of its dominion; and we can discern the three or four great lobes of which it consists all surrounded by the gauzy cloud that tells of the thousands of translucent polyps projected from every part of its periphery. Fine as is that specimen, however, there are scores of others, many of which are of equal dimensions, and more easily accessible. By the aid of the hammer and cold-chisel, we may easily secure a specimen without harming it, after searching a while to select one which is seated on some projection of the rock that can be struck off. Thus removed, and at once transferred to one of our collecting jars, the curious compound animal will in captivity display its beauties, though, it must be confessed, it is often rather bashful before company. The lobes into which the mass is divided are sufficiently like stumpy fingers to have given it a popular designation, while their dull white hue has suggested that the fingers are those of a corpse. The animal is sometimes, however, called Cows’ paps, and sometimes Mermaids’ gloves; but I think this latter is a book name.

When we examine it in the aquarium, after it has recovered its equanimity disturbed by the rude shocks of the hammer battering about its castle, we see that the lobes are greatly swollen and sub-pellucid, from the imbibition of water into the canals with which its whole substance is penetrated. When out of water the surface was studded with shallow pits, as if the poor thing had at some period of its history been afflicted with the small-pox. Now, however, these pittings reveal their true character; for each has protruded itself in the form of a long but slender polyp, of exquisite translucency and perfect symmetry. It resembles a tubular flower with eight narrow pointed petals, which arch outward like those of a campanula or tulip. Each petal carries on its edges a row of very slender transparent filaments, arranged like the teeth of a comb, which also arch downward, and greatly augment the beauty of the flower-like polyp.

Structurally, this polyp is closely allied to the common forms of the Sea Anemones; the most obvious peculiarity being, that a multitude are combined into one mass, with a common life animating the whole. The fleshy mass is of a spongy texture, full of branching water-canals, and containing a multitude of calcareous spicula of characteristic forms. They resemble gnarled branches of oak, with the branchlets broken off, leaving ragged ends. The skin of the polyps contains, at certain fixed spots, groups of similar spicula, but much more minute. The microscope is necessary to discern these, as well as some other details of the organization of this very interesting creature.