PREVIOUS INTERPRETATIONS OF CNIDARIA 



83 



Fig. 15. Young ontogenetic phase of Ctenophora; the dense dotted 

 cells are the primordium of the mcsohyl (mesoderm). A, longitu- 

 dinal section. B, oral view of the embryo (after Us). 



without an esprit, particularly in those cases where no fossil 

 documents can be found, yet we should realize that this is far 

 from a "fantastic theory" and "theoretical vaporizing." 



It should be mentioned in this connection that it is wrong 

 to speak about a "degradation of ctenophores from polyclad 

 larvae;" on the contrary, in my opinion, the evolution of 

 Ctenophora as animals that live in plankton has been pro- 

 gressive; their starting point, the supposed polyclad larva, has 

 also reached a much higher level of evolution than any 

 constructed planuloid form of an "Urcoelenterate" from 

 which Hyman derives both Cnidaria and Ctenophora by way 

 of an equally constructed medusa, a construction which itself 



