404 



THE EVOLUTION OF THE METAZOA 



the word. The temporary development of a few pairs of 

 coelom sacks that can be observed in the larvae of 7\nnelida 

 has nothing to do with the tetramerous Cnidaria. We must 

 therefore resolutely reject the idea of a derivation of polymery 

 from oligomery (Ivanov; we usually think here of trimery). 



Fig. 55. Derivation of bilateral symmetry \^'ith "larval segmen- 

 tation" from tetraradial symmetry of supposed primiitive cnidarian 

 by A. Remane (A-C). D, Remane's construction of a primitive seg- 

 mented metazoon. E, Jagerstens "bilaterogastrea." 



as well as of a derivation of polymery from cyclomery (Sedg- 

 wick, and many other zoologists after him, e. g. Remane and 

 Jagersten cf. Fig. 55). 



In our system the Polymeria must precede the Oligomeria, 

 and the primitive Oligomeria, the so-called Tentaculata, can- 

 not be interpreted as a transitional form between the un- 

 segmented and the polysegmented Eumetazoa. This is a ne- 

 cessary consequence of the fact that we derive the Polymeria 

 from an amerous state by way of a polymerization of several 



