an inch in height, whose lower extremities are of no greater thickness than the thread from which they spring ; with a head-like lobe at the summit, separated from the body by a constriction, immediately below which two lengthened arms project in a direction towards the axis of the tube.

Such is the external form of these animals, and their movements are still more extraordinary. The head-lobe of each one moves to and fro freely on the neck, the body sways from side to side, but still more vigorously backward and forward, frequently bending into an arch in either direction; while the long arms are widely expanded,

tossed wildly upward, and then waved downward, as if to mimic the actions of the most tumultuous human passion.

Whenever the Sabella protrudes from its tube, these guardian forms are pushed oat, and remain nearly in contact with the Annelid's body, moving but slightly ; but no sooner does it retire than they begin instantly to bow forward and gesticulate as before. These movements are continued, so far as I have observed, all the time that the Sabella is retracted, and are not in any degree dependent on currents in the surrounding water, whether those currents be produced by the action of the Annelid or by other causes. They are not rhythmical ; each individual appears to be animated by a distinct volition.

Applying a higher magnifying power than we have yet used to the animals, we find that the head-lobe incloses a central cavity ; that the arms are also hollow, with thick walls, marked with transverse lines, indicating flattened cells, and muricated on the exterior ; and that the body contains an undefined somewhat opaque nucleus, doubtless a stomachal cavity.

I cut out, with fine scissors, a segment of the tube, including two of the parasites, with the portion of the network of threads that carried them. They have become immediately paralysed by the division of the threads, but those that remain on the tube are unaffected by the violence. Subjecting one of the animals so cut out to the action of the compressorium, with a power of 560 diameters, the arms are seen to be formed of globose cells, made slightly polyhedral, or many-sided, by mutual pressure, set in single series. The interior of these organs is divided by partitions, placed at intervals of about the diameter. Some at least of the cells contain a small bright eccentric nucleus.

When the tissues were quite crushed down by the pressure of the compressorium, a quivering motion was visible among the disjointed granules, but it was very slight.

trace of cilia, nor any appearance of ciliary motion, was perceptible during life.

When I first discovered these strange beings, I was as much astonished by what I saw as you are ; nor could I imagine to what class of animals they were to be referred. Neither did I know whether their presence on the tube of the worm was a mere accident, or whether it indicated a predominant instinct. On both these points, however, light has been shed.

This larger Sabella tube was not the only one infested with the parasites. I observed them on at least two smaller specimens of the same species, in the same situation, and with precisely the same movements. The extremity of one of those smaller tubes I cut wholly off, and placed in the live-box of the microscope. Two of the parasites only were on it, which were active at first, but in about an hour—probably from the exhaustion of the oxygen in the small quantity of water inclosed—they decomposed, or rather disintegrated, the outline dissolving, and the external cells becoming loose and ragged, and the whole animal losing its definite form.

One of these specimens, however, while yet alive and active, afforded me an observation of value. I had already associated the form conjecturally with the Hydroid Polypes, and was inclined to place it in the family Corynidce, considering the arms to be tentacles, and the headlobe to be homologous with them in character, but abnormal in form. It appeared to be a three-tentacled Coryne, with the tentacles simple instead of having heads. But while I was observing the individual in question, I saw it suddenly open the head-lobe, and unfold it into the form of a broad shovel-shaped expanded disk, not, however, flat, but with the two halves inclining towards each other, like two leaves of a half-opened book. This immediately reminded me of the great sucking-disk which, as I lately told you, I had seen evolved from the obtuse summit of Stauridia producta, and confirmed my suggestion of the natural affinities of the form.

Altogether unlike, in their shape, and in the unwonted vivacity and peculiar human character of their movements, all the other members of their natural family that I had ever seen or heard of, these curious creatures have afforded much entertainment, not only to myself, but to those scientific friends to whom I have had opportunities of exhibiting them. When I see them surrounding the mansion of the Sabella, gazing, as it were, after him as he retreats into his castle, flinging their wild arms over its entrance, and keeping watch with untiring vigilance until he reappears, it seems to require no very vivid fancy to imagine them so many guardian demons ; and the Lares of the old Roman mythology occurring to memory, I described the form under the scientific appellation of Lar Sabellarum. You may, however, if it pleases you better, call them " witches dancing round the charmed pot." *

The Polypes that we have as yet been looking at are all of simple structure individually, though some of them we have seen united into a very populous community of compound life. \Ye will now look at some whose organisation is of a higher, that is, more complex character.

On this old worm-eaten oyster-shell, which has been dredged up from the bottom of the sea, you observe several rounded lumps. They are of a cream-white hue, of somewhat solid texture, tough and hard to the touch, and studded all over with shallow depressions or pittings. The largest of these is not more than an inch and a-half in height, by two-thirds of an inch in thickness ; but specimens often occur of twice or thrice these dimensions,

Since my first discovery of this strange form in 1855, and my memoir on it in the " Trans, of the Linnean Society," it has remained unrecognised (and, indeed, somewhat suspected) for seventeen years. In the summer of 1872, however, it again occurred to the observation of the Rev. T. Hincks, who published a paper, with illustrations, on it, in the Annals and Mag. of Nat. Hist, for Nov., 1872.

and much more divided than this ; sometimes forming a rude resemblance to a hand of stumpy, round fingers of sodden flesh; whence the fishermen call the object " Dead men's fingers," or sometimes, by a comparison equally apt, " Cow's paps." To zoologists it is known as Alcyonium digitatum.

Certainly there is nothing very attractive in these white lumps as they now appear; but then they are now in undress ; they do not expect to see company out of water. Their drawing-room is beneath the waves, in some submerged cave of ocean, where the sun's ray never penetrated, and where the only light is that dim green haze reflected from the sand and shingle of the sea-floor ; save when, on gala occasions, perchance, the Laomedece that fringe the walls light up their myriads of fairy lamps, and the tiny Medu&ce crowd into the watery festivities with their elfish circlets and spangles of living flame. It is then that the Cow's paps " take their hair out of paper," and display their loveliness to advantage.

Unfortunately, we have no card of invitation to these submarine routs, but perhaps we may induce one of the more juvenile of these beauties to indulge us, as a special favour, with a sample of the effect ; particularly if we can improvise a ball-room suited to the occasion. Let us try.

Selecting the very smallest specimen—a tiny thing no larger than a pea— I try to detach it without injury, by inserting the tip of my pocket-knife under the frilled lamina of oyster-shell on which it rests, and working off the fragment. I have succeeded : here it is, its attachment unbroken : it is still firmly adherent to the severed slice of shell, which is so small that I can drop it with its burden into this narrow trough of glass. The whole concern, trough, shell, and polype, is now to be dropped into this capacious jar of freshly dipped sea-water, and put away for an hour into a dark closet.

Now let us see the result. Yes, it is as I expected. The united stimulus of the darkness and the sea-water has acted on the Cow's pap, just as would the rising and covering tide in its native cavern, after it had been left exposed for some hours by the recess of the sea. It is fully expanded, and is now as lovely as just now it was unpleasing.

In the first place it is swollen to twice its former dimensions, and has acquired at the same time a semi-pellucidity, and a more delicate hue. But in the place of the pits on the surface (there were not more than half-a-dozen in this little specimen, which makes it more suitable for examination), it is covered with tall polypes, standing out on all sides, of crystalline clearness and starry forms, each eminently beautiful in itself, and surrounding the whole mass with a sort of atmosphere of almost invisible and impalpable lustre peculiarly charming.

Coy as these deep-water strangers are of displaying their beauties in our glaring aquariums, they will bear with equanimity a good deal of shaking, when once they are expanded. Hence I may be able to transfer the trough with its contents from the jar to the stage of the microscope, and thus enable you to gaze on its details for a little while, before the dull sensorium of the creature is sufficiently warned of its ungenial position to cause it to shut itself up and resume its ugliness.

As the protruded polypes are exactly alike, it will be enough to confine our attention to one. It is an elevated tubular column of translucent substance, terminating in an expanded flower of eight slender pointed petals, which spring outward with a graceful swell, so as to give the form of a shallow bell to their general outline. The base springs, like the foot of a tree, from the margin of a cell, which penetrates the substance of the mass, into which we can see far down, and into which the whole of the now extended and expanded blossom was withdrawn when we first saw it, leaving only the shallow depression to mark its situation.

The form of the column is in general that of the trunk of a tree, or that of a long cone ; but there is a sudden constriction just above the base, and another below the point, where what may be called the flower expands. It is the petals of this latter which constitute the principal charm of this creature. They are, properly speaking, the tentacles of the polype, answering in function and position to those on the Laomedea, but differing considerably from them in form. Each of the eight is thick and broad at its

POLYPES OF COW S PAP.

origin, and quickly tapers to a point : on each of two opposite sides, viz., those which look towards the two adjoining tentacles, runs a row of delicately slender filaments, which at the middle part of the tentacle are moderately long, but diminish regularly as they approach either end. Starting from the side of the tentacle, in the plane of its transverse diameter, these elegant pinna? presently arch downwards, but with perfect uniformity and

Page 54 of 65