HYDROZOA. ITIL 
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, 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 fora species of root. The edges of the umbrella 
or mushroom are entire or dentate, sometimes elegantly scolloped, 
often ciliate, or provided with long filiform appendages which float 
vertically in the water. 
Sometimes the animal is transparent, and limpid as crystal ; some- 
times 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 trans- 
parent glass shade which covers a group of artificial flowers. 
The Medusz are animals without much consistence, containing 
much water, so that we can scarcely comprehend how they resist the 
agitation of the waves and the force of the currents; the waves, 
however, float without hurting them, the tempest scatters without 
killing them. When the sea retires, or they are withdrawn from their 
native waters, their substance dissolves, the animal is decomposed, 
they are reduced to nothing ; if the sun is strong, this disorganisation 
occurs in the twinkling of an eye, so to speak. 
When the Medusz travel their convex part is always kept in 
advance and slightly oblique. If they are touched while swimming, 
even lightly, they contract their tentacula, fold up their umbrella, 
and sink into the sea. Like Ehrenberg, M. Kolliker thought he dis- 
covered visual and auditory organs in an Oceania, and Gegenbauer 
thought he detected them in other genera, such as AAzzostoma and 
Pelagia. The eyes are said to consist of certain small, hemispherical, 
cellulose, coloured masses, in which are sunk small crystalline 
globules, the free parts of which are perfectly naked. The supposed 
auditory apparatus is seated close to these organs ; they are small 
vesicles, filled with liquid; the eyes having neither pupil nor cornea. 
But it is in their reproduction that these evanescent beings present 
the most marvellous phenomena. At one period of the year the 
