The substance of the disk presents an uniform cellular appearance internally, but the cellular substance being very soft, no trace of fibre is observable. Taken from the sea and laid upon a stone, a Medusa weighing fifty ounces will rapidly diminish to five or six grains, sinking into a sort of deliquescence, from which Spalanzani concluded that the sea-water penetrated the organic texture of its substance, and constituted the principal volume of the animal. Those which have cilia round their margins have also cellular bands running along their bases, and most of the projectile and extensile tentacula and filaments have sacs and canals containing fluids at their roots. Suckers are also found at the extremities, and along the sides of these tentacles in several genera are suckers, by which they are able more securely to catch their floating prey, or to anchor themselves when at rest. The indications of nerves or nervous system are too slight to be received as evidence, although Dr. Grant observed some structure which he thought could only belong to a nervous system, and Ehrenberg thought he observed eyes in _Medusa aurita_, as well as a nervous circle formed of four ganglion-like masses disposed round the mouth. But most naturalists seem to be of opinion that touch is the only sense of which any conclusive proof can be advanced. Here we behold a class of bell-shaped semi-transparent organisms, which float gracefully in the sea--a great family of soft, wandering animals, constituted in a most extraordinary manner. They look like floating umbrellas, breeches, or, better still, floating mushrooms, the footstalk replaced by an equally central body, but divided into divergent lobes at once sinuous, twisted, and fringed, so that one is at first tempted to take them for a species of root. The edges of the umbrella or mushroom are entire or dentate, sometimes elegantly figured, often ciliate, or provided with long filiform appendages which float vertically in the water. Sometimes the animal is uncoloured, and limpid as crystal; sometimes it presents a slightly opaline appearance, now of a tender blue, or of a delicate rose colour; at other times it reflects the most brilliant and vivid tints. In certain species the central parts only are coloured, showing brilliant reds and yellows, blues or violets, the rest being colourless. In others the central mass seems clothed in a thin iridescent or diaphanous veil, like the light evanescent soap-bubble, or the transparent glass shade which covers a group of artificial flowers.