108 



THE EVOLUTION OF THE METAZOA 



can see that in the whole large group of Octactiniaria among 

 Anthozoa, not a single primarily (in this case not even secon- 

 darily) solitary species does appear. Those species that have 

 occasionally been described as solitary (e.g. Haimea, Monoxeniay 

 etc.) were primary zooids (or oozooids) only before they 

 began to develop further into colonies. This situation in Oct- 



Fig. 19. Podocysts or resting bodies as remains of rhizome. A, 

 scyphopolyp of Chrysaora hyoscela (after Hadzi). B, hydroidpolyp 

 of Ostroumovia harii (after Uchida and Nagao). C, Hypolytus sp. 

 (after Miles). 



actiniaria, naturally in connection with other properties and 

 characteristics, proves that Octactiniaria do not correspond to 

 the primitive subtype of Anthozoa as this has frequently been 

 believed. The Actiniaria can with all certainty only be consi- 

 dered as primarily solitary animals (with, as it seems, one 

 species only which forms colonies), as can also, in addition 

 to these, the Ceriantharia with their partly rounded off and 

 partly flattened aboral end. 



In the Scyphozoa the abolition of the colonies of polyps has 

 gone furthest. In these the species with cormi, which have 

 a completely irregular growth, are a real rarity now (the so- 

 called Stephanoscyphus, the polyp generation of Nausithoe) ; there 



