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capable of great increase of volume when filled with water. An 

 Alcyonia which, when contracted, looks like a piece of red or 

 yellow sponge, is scarcely to be recognised when fully distend- 

 ed. It is then three or four times its original size, becomes al- 

 most transparent and unsubstantial, and is covered with polypes 

 that look like tiny transparent flowers. 



Almost still more beautiful are the coral colonies called Pen- 

 natulae or Sea- feathers, which can also expand and contract 

 at will. In the last state they look very ugly, like some shrunken 

 dead creature. But at other times they are distended to tran- 

 sparent beauty, standing erect, with all their wing or leaf-like 

 appendages studded on their upper edges with charming polypes, 

 the tentacles of which may often be observed in motion. 



The Virgularia or Sea-rod , belongs to the same family, 

 but its polypes are not attached to such leaf-like appendages. 

 The Pennatulae can move freely about, and bore their fleshy 

 extremities into the sand, an operation which may sometimes 

 be observed in the Aquarium. 



Iledusac (Jelly-fish) 



Any one who has visited northern coasts and remembers ha- 

 ving often seen ugly jelly-like lumps lying on the strand, looking 

 still more disgusting because of the coloured -stripes that cross 

 them, will scarcely believe it, when he sees swimming about 

 in the Aquarium, and is told that they are those very lumps, 

 the large medusae Rhizostoma and Cassiopeia, or the smal- 

 ler forms of the Pelagia, Oceania, Geryonia, and Cunina. 

 These living medusae make a very different impression to that 

 excited by the ugly dead jelly-fish. Their almost total transpa- 

 rency , beautiful motions , and often splendid colours attract 

 every eye. But on looking at these animals the visitor must 

 somewhat limit his idea of what an animal consists of. The 

 Medusae which are nearly related to the polypes have just as 

 little as the latter anything that is like a head, arms or legs. 

 They are merely a sort of shallow reversed cup, not unlike an o- 

 pen umbrella or a mushroom, and move by therythmic contractions 

 of their gelatinous body. On the edge of the cup are the organs 

 of sight and hearing, and it is generally also surrounded by a 

 nerve-ring. From the centre of the hollow of the cup hangs a 

 long gelatinous transparent stem which is hollow and provided 

 with a mouth orifice. This stem ortrunkis sometimes for example 

 in the Cassiopeia and Rhizostoma very broad and consists 



