86 THE EVOLUTION OF THE META20A 



problem of the origin of Ctenophora in the nebulous idea 

 of Gastraeadae which they consider to be the common origin 

 of Spongiae, Cnidaria, and Ctenophora, while at the same 

 time they wish to give up the old taxon of Coelenterata. This 

 should be done, according to this interpretation, first, because 

 their supposed common origin goes too far back into a 

 vague past, and, secondly, because in the mean time these 

 three types (Spongiae, Cnidaria, Ctenophora) have had such 

 widely diverging evolutions that it is now senseless to try 

 to bring them into one unit. E. Perrier (1921 pp. 284-5), for 

 example wrote in connection with his statement that Cteno- 

 phora had a genuine mesoderm, "... font douter qu'on 

 doive rattacher reellement les Ctenophores a I'embranchement 

 des Coelenteres." In spite of this E. Perrier (1921) divides 

 Metazoa into Phytozoaires and Artiozoaires, and he mentions 

 as "embranchements" of Phytozoaires: (1) Coelenteres, (2) 

 Spongiaires, and (3) Echinodermes. 



We are fully convinced that sooner or later, the taxon 

 Coelenterata will be completely abandoned and that Cnidaria 

 will be the only group which will survive within the frame 

 of Coelenterata; so that finally the names Cnidaria and Coelente- 

 rata will become synonymus. In this way Cnidaria will become 

 isolated, yet this isolation will be an apparent isolation only, 

 because at the same time it will become possible to connect 

 them, by w^ay of a supposed derivation from Turbellaria, to 

 a higher category, i.e. to the large group (phylum s. lat.) 

 of Ameria. 



Here it should suffice briefly to touch the problem of the 

 connection between Cnidaria and Echinodermata. This prob- 

 lem has repeatedly appeared in the literature since the days 

 of Lamarck and Cuvier and it is connected wdth the names 

 Radiata or Radialia. The name itself indicates that it is the 

 similarity of symmetric condition only which is here constant- 

 ly being taken into consideration; yet the conditions are not 

 identical: in Echinodermata a pure radial symmetry is really 

 an exception due to a secondary omission of their anal orifice 



