To a cursory observer the appearance of this animal is that of a bladder filled with air, with a low, longitudinal crest, supposed to resemble a sail both in shape and function, and many tendrils of various lengths hanging loosely in the water below; without a visible orifice or organs of voluntary motion. More closely examined in its native element, it is found to possess a front which is marked by a small perpendicularly oval space, thinner than the neighbouring surface, and conveying the idea of a mouth; and to the inner side of which is attached an organization presently to be described more at length.

From the margin of what, for the sake of distinction, I have designated the oral space, a number of lines proceed longitudinally along the surface, converging again near the pointed posterior portion, round a space and apparent aperture in a line not exactly straight above the extremity. Examined within, the wall of this membrane is encircled by another set of fibres, which encompass the sides at right angles to the former; and it is by the combined action of these, that the complicated motions are performed of which the creature is capable.

What is denominated the sail or crest, is a plaited membrane passing lengthwise from a short distance above the oral space, to within about an equal distance of the posterior extremity. It varies a little in breadth in different specimens, but in a large individual is about an inch in height, with an edge on the summit, but spreading below like the ridge of a house, and within the eavity is divided into segments. The structure of the inflated body is diaphanous; and viewed by the aid of light on the anterior portion of the right side, rising above the tendrils with which below it is connected, is an extended opacity, irregularly circular above, and well defined, indicating a structure differing from the other portion, though not such as interferes with the arrangement of the muscular fibres.

The tendrils are of three sorts. The first, towards the front, are placed on and under one side of the ordinary line of suspension in the water: they are short, clustering, and tufted on their pedicles. The other two sorts of tendrils are long; some a few inches, and some nearly a yard in length, but none placed behind the middle of the body; and the first elongated ones, placed below, are formed of a thread of membrane accompanied and encircled by a line of flattened beads, which obey the influence of the will in contraction, extension and lateral motion. The third sort are the longest; their base is thick and firm, having the muscular structure continued

along their course, and at the end a membranous dilatation, from which springs a thread encircled by a beaded line, which at first is convoluted and doubled on the base, and then accompanies the thread to the end. The peduncles of these latter tendrils, about an inch in length, are fixed higher on the side than the former; but seem exceedingly liable to injury, since it is rare that all of them are perfect. The membranous threads appear to be the branchia, but the anterior branched tendrils seem rather to be absorbent organs, like the roots of a tree, affording the only source of nutriment, which I imagine to be assimilated in the reddish side of the internal sac; and which, besides its redness, is of a rather thicker substance than the surrounding structure.

In its healthy state the colours of this animal are beautiful; the crest being striped alternately with light blue and crimson or pink, and the sides similarly tinted, with reflections. The tendrils are of a darker blue, and sometimes a dull purple.— Examined within there is a thin membranous structure, which is necessarily pierced when the cavity is opened. On its anterior portion it is firmly attached to what I have denominated the oral space; it is also, but very slightly, attached posteriorly; and along the upper margin there is a varying number of branched appendages, each of which occupies a portion of the chambers of the crest. In some specimens, where the crest is low, they are fewer, less branched, and more obtuse; in others, long, slender and much divaricated. In the living state this membranous structure is so closely applied to the external muscular parietes, as not to be discerned through it, the cavity appearing empty. They are also so little adherent, except at the end, as to separate spontaneously; but still between them both is a slight villous coat, adhering to the external or containing portion, and which is the chief, if not the only seat of the colour. It is probable that the chief interchange of vital action is through this structure, which, although so slight and unadherent, is as closely connected as in some other animals or structures in which no more certain mode of communication has been traced. Many morbid growths in the human body have even less connection with the common vitality. This internal sac contains nothing but air, which appears to be secreted into it by the crest, that being its chief, if not the only office. No trace of food can be found, nor any separate organization, except a reddish thickening, already alluded to, at one portion of the surface. It is this which appears externally; and it seems just to owe its appearauce to vascularity, though no separate vessel can be distinguished; it is probably the seat of the vital actions,

from which the splendid colours, and the acrid fluid covering the surface, as well as the ordinary supply of nutriment, are derived.

It has been a general opinion that the air in the cavity of the body is collected at the will of the animal, and that it can be expelled at pleasure, or through fear of danger. Neither of these ideas, however, appears to be accurate; for in regard to its accumulation, it is clearly not received from without, and as to the power of expulsion in any manner of haste, especially in storms, and to enable it to sink from danger, common observation proves the contrary; for they are seen floating on the most turbulent waves, and are frequently thrown ashore in tempests. Examination, indeed, cannot fail to persuade any one that a creature with so little of solid substance in its composition, cannot be made to sink without the almost total expulsion of its air, which ordinary mechanical compression does but little towards effecting; and when this expulsion is procured by puncture, which may amount to what the creature can effect by great effort, the animal may be made to shrink into a comparatively small compass, without at all approaching to a condition in which it can sink below the surface. I have discharged nine-tenths of the contained air, thereby causing a shrivelling of the external membrane, without bringing it to a state in which it did not swim buoyantly on the water.

But an examination of the Physalia when in undisturbed liberty will show that the real use of the inflated condition is not buoyancy alone. The accumulation of air will then be seen absolutely necessary as a fulcrum or point of support for the action of the muscular structure; and accordingly, the creature, by the contractions of portions of its surface and the relaxations of others, projects the oral extremity into the form of a snout, lifts or moves it towards either side, and depresses portions of the centre, lengthening or shortening itself, and especially dilating towards the side from which the tendons are dependant, according to its pleasure. But perhaps none of its actions are so capable of displaying the management of a complicated intention, as those by which the animal contrives to fall on its side from its more usual position with the crest aloft. The anterior portion is first dilated, by which a basis is formed capable of sustaining the whole bulk: the hinder part, for about a third of the length, is then rendered slender and elevated; in which condition but little of the surface is immersed, and a very small degree of inclination to either side causes it to fall over, with the crest on the surface

of the sea: a position perhaps rendered necessary when, from drying winds, the top of the membrane has become rigid.Its most favourite position in the water is resumed by again taking an elongated shape; and it must be remembered that these actions take place in an animal, in which minute research has not been able to detect a nervous system. These motions also, of a creature inflated with air, derive much interest from the explanation they afford of those faculties of some animals which appear to have received an erroneous or imperfect interpretation. Thus the prehensile organs of Echinus and Asterias, which are hollow, and capable of being drawn close to or within the body, are described as being protruded by simply propelling a fluid along their course, which fluid, when no longer wanted for this purpose, is again returned to the cavity. At this point the explanation ends; propulsion being regarded as the sole object of the function. Such, however, does not appear to be the case; the distension effected by the propulsion of fluid in the radiate animals, and of air in Physalia, being only the first step in the process, and providing a fulcrum for the support of muscular effort the chief object in view. In the tube of the Lepades the action is of a similar kind, though more complicated, owing perhaps to its annulated structure. The distension caused by the contained fluid in the latter is less considerable, and the animal sometimes hangs in a flaccid state, at its full length. When about to move, compression of the fluid fixes the centre of motion, which is rendered still more energetic by collecting and fixing it at the root, or in particular departments.

The remarks here offered may be extended to many of the voluntary motions of other animals of soft texture; developing a contrivance by which apparent contrarieties are reconciled, and creatures having so little firmness in their composition enabled to perform motions requiring tense support: the fulcrum which in the higher animals is the heaviest portion of their structure, and acts by gravity as well as strength, being in them no less effective as a moving power, and yet so light as to serve the office of a balloon.

It is well known that the Physalia, and several species of Medusa, are capable of inflicting a stinging sensation on the hands that touch them. The certainty of this admits of no doubt; the effect being severe even in persons whose skin cannot be supposed endued with remarkable delicacy. A sailor-boy, a short time since, was so severely affected from handling a single specimen, that the skin peeled from the whole surface of his hand. Yet, with the intention of expe

riencing this, I have repeatedly handled numerous specimens of both genera, swimming at large and out of the water, living and dead, yet without being made sensible of any unpleasant effect.'

ART. IX.-A Catalogue of some of the most interesting Plants collected in the neighbourhood of Swansea, Glamorganshire, during the past Summer [1839]. By THOMAS BRUGES FLOWER, Esq., F.L.S.

RANUNCULUS Lingua. In great abundance on Cromlyn bog and Neath canal.

TROLLIUS Europæus. "On the banks of the Dylais, above the waterfall at Aberdylais, and in moist meadows between Pont nedd Vachu and Usgord Eynon Gard."-Dillwyn.

HELLEBORUS foetidus. In the woods at Park mill, towards Pennard castle, in great abundance,

DELPHINIUM Consolida. I have not been able to detect this plant in Swan

sea Bay; it is mentioned in New Bot. Gui. as growing there in plenty NYMPHEA alba. Abundantly in the canal going to Neath.

MECONOPSIS Cambrica, "At the waterfalls about Pont nedd Vachu, in the Dylais Valley above Aberdylais, plentiful."—Dillwyn.

GLAUCIUM luteum. Frequent about Salthouse point, and in many places by the sea-shore.

MATTHIOLA sinuata. On the sands between Swansea and the Mumbles, but is now much less plentiful than formerly.

COCHLEARIA danica. Very abundant on rocks about the Mumbles lighthouse.

DRABA aizoïdes.

"Found growing in the greatest abundance on the walls of Pennard castle, near Swansea, where it was first noticed by the late Mr. Lucas." It was still in great plenty when I visited the spot, August, 1839.

THLASPI alpestre. "About Pont nedd Vachu."-Dillwyn.

HUTCHINSIA petræa, On the walls of Pennard castle.

TEESDALIA nudicaulis. "On wastes and roadsides about Swansea, not uncommon."-Dillwyn,

LEPIDIUM Smithii. Everywhere on the sea-shore.

Draba, "The station given for this plant is now destroyed, the ground having been built upon."--Dillwyn.

ruderale. "Occasionally found on rubbish-heaps and ballastbanks about Swansea.”—Dillwyn.

BRASSICA cheiranthus. "This interesting plant was detected on the sands near Pennard castle, in the summer of 1838, by Mr. Woods." It was still plentiful in the place mentioned when I visited the spot in company with my friend C. C. Babington, Esq. in August last.

1 Some interesting remarks on the Physalia, which perhaps may not have fallen under the observation of Mr. Couch, are to be found in the 'Proceedings of the Zool. Society for 1837, page 43, by Mr. George Bennett. -Ed. 3 Q

VOL III.-No. 35, N. s.