THE JELLYFISH AND THEIR ALLIES 



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Taking first the free-swimming jellyfish, the larger and more characteristic 

 forms are distinguished by their delicate coloring. The yellow and yellowish-red 

 Chrysaora ocellata are seen floating past in thousands off the southern coast of 

 Norway. The western harbors of the Baltic Sea, after continuous northerly winds, 

 are often filled with whole banks of the blue Aurelia aurita, and the splendid 

 Rhizostoma are constantly to be met with in the Mediterranean and Adriatic Seas. 

 On a fine spring day they are almost always to be found on the shore, where these 

 large, reddish blue, living hemispheres are wrecked, and soon melt away. Indeed, the 



Rhizostoma. 



bodies of all jellyfish contain so large a proportion of water that when a tolerably 

 large specimen is laid on blotting paper it evaporates, leaving no other trace than 

 its outline on the paper. In these medusae which are well known to all who 

 dwell on the coast, and range from one to seven inches in diameter we have the 

 most highly developed of the simple Coelenterates. Their body consists for the 

 greater part of the circular umbrella, the margin of which is notched all round so 

 as to hang down in large or small lobes. There are also, along the margin, from 

 four to eight or more eye-like spots, and extensible filaments. At the centre of the 

 lower side of the disc is the mouth, which in some forms lies at the end of a project- 



