arms as if they were indeed the serpents with which Medusa's head was surrounded. The least impurity in the water will cause these strange beings to break themselves to pieces in this extraordinary manner, but they never seem to disintegrate themselves with such rapidity as when they are touched or otherwise alarmed.

The lamented Professor Forbes has left an admirably quaint description of this suicidal process. Having in vain attempted to secure a perfect specimen of a Brittle-star, he thought that he might achieve that object by having a pail of fresh water lowered into the sea, so that as soon as the dredge reached the surface of the sea it might be transferred to the bucket of fresh water, and all the inmates killed at once by the shock.

A fine specimen of the genus Luidia was then taken in the dredge. "As it does not generally break up before it is raised above the surface of the sea, cautiously and anxiously I sank my bucket to a level with the dredge's mouth, and proceeded, in the most gentle manner, to introduce Luidia to the purer element. Whether the cold element was too much for him, or the sight of the bucket too terrific, I know not; but in a moment he began to dissolve his corporation, and at every mesh of the dredge his fragments were seen escaping. In despair, I grasped the largest, and brought up the extremity of an arm with its terminating eye, the spinous eyelid of which opened and closed with something exceedingly like a wink of derision."

These Brittle-stars are, however, extremely capricious in their exercise of this curious power. It sometimes happens that, as in the instance so amusingly narrated, the creatures break themselves to pieces without any apparent provocation, while, in other cases, specimen after specimen may be taken, handled, killed, or wounded, without the loss of a ray. Even in the aquarium, they are equally uncertain in their habits, at one hour being entire and splendid specimens, and at the next being little but a solitary disk amid a ruined heap of broken arms.

THE word Ophiurus is of Greek origin, signifying snake-tail, and is therefore very appropriately given to these curious beings, whose slender arms twist and coil just like a handful of small serpents.

The Ophiuri are quite as voracious as the ordinary Star-fishes, and are able by means of the long arms to convey food to the mouth, which is placed in the central disk. The young of these Echinodermata are quite as curious as those of the sea-urchins, to which indeed they bear some resemblance. They have long been known to naturalists under the title of Easel animalcules, on account of their peculiar shape, their real origin not being suspected until later years. It is totally unlike the form which it attains when mature, and the relationship between the adult Star-fish and the Pluteus, as the larva is termed, has been well compared to the relation of an embroidery frame to the pictured canvas within. Both the species shown in this illustration are inhabitants of the British seas.

THE wonderful creature which is called by the name of SHETLAND ARGUS is one of a most remarkable genus of Star-fishes, which are remarkable for the vast development of their arms.

Although the whole mass of arms is of so complicated a description, it will be found, on carefully examining the creature, to be formed by the simple process of twofold division. From the central disk spring five stout arms, each of which almost immediately divides into two smaller arms, and these again into two others; so that in a fine specimen the number of little arms or tendrils, if we may so call them, exceeds eighty thousand. All these organs are extremely flexible, and quite under the control of the animal, which is able to close or expand them at will. When the extremities of the arms are drawn together, it will be seen that the whole animal assumes the shape of a globular basket; and in consequence of this resemblance, the name of Basket-urchin, or Sea-basket, has been proposed for the creature.

It takes its food by means of these wonderful arms, using itself, in fact, like a living casting net, surrounding the prey with the spread arms, and enclosing it within their multitudinous lines. It has been known to embrace in this manner a fisherman's bait, and to allow itself to be drawn to the surface without loosing its hold. It is one of the deep sea Star-fishes, and is very seldom taken except by means of the dredge or line.

The structure of the Shetland Argus is most marvellously complicated, inasmuch as each of the numerous arms is composed of an enormous number of small joints, each exactly in its place, and so beautifully connected together, that they are as flexible as silken cords, and yet as perfectly under the command of their owner as if they were restricted to the original five from which they take their origin.

THE elegant and graceful Star-fish which is appropriately named the FEATHER-STAR, is a native of our own coasts, and has always attracted the attention of sea-side observers. It is not very readily seen, being one of the deep water species, but it may be captured by means of the dredge, and will live for some time in the marine aquarium. It is a very active being, combining in its own person the accomplishments of many different Starfishes. For example, it can crawl with tolerable speed over the ground, can swim through the water with sufficient power to direct its course, can float about at will, driven by the tide, and will sometimes clasp pieces of floating wood so as to be carried along by the waves without any fatigue.

Its habits while in the aquarium are very interesting, and have been well described by Mr. Gosse:

"In captivity, the Feather-star sits upon the frond of a sea-weed or on a projecting angle of rock, which it grasps very firmly with its clawed filaments, so firmly that

it is difficult to tear it from its hold. When violence is used, it catches hold of its support or any other object within reach with the tips of its arms, which it hooks down for the purpose, and with its pinnæ, so that it seems furnished with so many claws, the hard stony nature of which is revealed by the creaking scratching noise they make as they are forced from any hold, as if they were made of glass.

I was surprised to observe that several of the arms were unsymmetrically short; and on examining these with a lens, saw distinctly that each had been broken off, and was renewed; the new part agreeing in structure and colour with the rest, but the joints were much less in diameter; and this difference was strongly marked at the point of union, the first of the new joints being not more than one-third as wide as its predecessor. The appearance much reminded me of a lizard renewing its tail.

In sitting, the Feather-star bends its arms with a sigmoid curve, the tips bending upwards. It waves them now and then, but not much, and remains long without moving from its hold. Though I repeatedly took it out of water, removing it forcibly, it manifested no tendency to voluntary dislocation."

Perhaps, however, the strangest part of the Comatula's life is its early youth.

Every one who has the least smattering of geology is familiar with the fossils called Encrinites, and is well acquainted with them under the different popular names that they bear. They are, or rather were, Echinodermata set upon a long flexible stalk, and being constructed, like the Star-fishes, of an enormous number of joints. Popularly they are known by the name of Stone-lilies, or Screw-stones, and their disjointed members are very familiar under the title of St. Cuthbert's Beads. The number of joints in an adult Encrinite is almost incredible.

In the head only of one specimen, no less than one hundred and fifty thousand joints have been calculated to exist, exclusive of the numerous parts of which the stem is composed. These joints are frequently found separated from each other; and as they are perforated by a small hole through which a thread might be run, they were formerly strung together and used as rosaries. Encrinites were found very plentifully in many marbles, which, according to Dr. Buckland's energetic language, are as entirely made up of the petrified remains of Encrinites as a corn-rick is of straws. These wonderful beings could hardly be dissected out of the stone by any exertion of human labour, but it is found that water will achieve a task at once too laborious and too delicate for human hands to undertake. It often happens that the abrupt faces of marble cliffs exposed to the weather, so that the annual rains are driven forcibly upon them, and by their continual action wear away the soft surrounding substance of the stone, leaving the harder forms of the Encrinites as memorials of the time long passed away.

The Encrinites have long ago perished, but there are still some existing species of stalked Echinodermata, which are closely allied to them, and are still more nearly connected with the history of the Feather-star. These are termed Pentacrinites, because their joints are five-sided. Many fossil species of Pentacrinites are found, and are seen in positions which seem to prove that they must have been adherent by their bases to floating objects, and thus carried about from one place to another, like the barnacles, which have already been described and figured.

ONE living species of these strange creatures is still in existence, and is shown in the accompanying illustration. This strange being is appropriately called by the name of Medusa's Head, as the many arms that wave about its summit bear some resemblance to the fabled head of Medusa, with its burden of venomous serpents.

It is not a very large species when compared with some of its fossil relatives, for the largest specimens hitherto discovered are only a few feet in length, and have a stem about as large as a common drawing-pencil. Several fossil species, on the contrary, are at least eleven or twelve feet in length, and measure a full inch across the stem. The MEDUSA'S HEAD is the only species at present known, though it is probable that others may be yet discovered. In the illustration, two specimens of this creature are given, the one to exhibit the head as it appears when expanded, and the other to show its aspect when closed.

The smaller figure represents a being discovered by Mr. Thompson, and called by him Pentacrinus Europeus. This little creature is, when full-grown, barely three-quarters of an inch in height, and with a stem no thicker than sewing silk. Without entering into the many and interesting details of structure, development. and the habits of this