HYDROZOA. Ill 



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 for a 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 slighdy 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 Medusae are animals without much consistence, containing 

 much water, so that v/e 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 When the sea retires, or they are withdrawn from their 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 Medusae 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. KoUiker thought he dis- 

 covered visual and auditory organs in an Oceafiia, and Gegenbauer- 

 thought he detected them in other genera, such as Rhizostoma 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 



