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THE AM ERIC AX NATURALIST. [Vol. XXXVII 



(hypogenic), development from the egg ; while in others, and by 

 far the larger number, development is indirect (metagenic), 

 exhibiting perfectly evident alternation of generations ; in this 

 case however, involving a distinct metamorphosis, the polyp 

 giving rise to a free-swimming ephyra which is in turn trans- 

 formed directly into a medusa. It should also be noted that 

 asexual budding is, unlike that of the former class, by the 

 transverse fission of the polyp body into a series of disks which 

 become free as ephyrae, as already noted. Direct asexual 

 budding frommedusoid organs, common in many I lyclromedusae, 

 is unknown among the Scyphomedusas. 



