78 THE EVOLUTION OF THE META20A 



Jiirgen W. Harms (1924) also separated Cnidaria from Cteno- 

 phora in his somew hat bizarre system of the animal world; 

 this separation was less radical than the former and it is based 

 on other reasons. The first of his three circles was sub- 

 divided into three subcircles; it is defined well enough because 

 it includes all the animal groups which have primarily— as 

 modified Gastraeadae— no anal orifice (aproctous animals; here 

 he should have omitted Spongiae); he uses for his subdivisions 

 the criterion of stability. Harms included in his first subcircle 

 Porifera, Cnidaria, and Turbellaria as labile and regulative 

 forms ("Regulationsformen"). The second subcircle includes 

 the parasitic Platyhelminthes as semi-stabile forms with a partly 

 constant number of cells. The Ctenophora and Acanthocephala, 

 as blindly ending branches of the animal world, with a constant 

 number of cells (this, however, is not even true for Ctenophora) 

 and their stability, have been placed by Harms into the third 

 subcircle; yet, as a matter of fact the Acanthocephala are not 

 primarily aproctous animals: the absence of the whole digestive 

 apparatus, and thus also of the anal orifice, is in these animals 

 a secondary phenomenon since the loss of these organs has 

 been caused by their parasitism. 



Among the almost innumerable attempts to construct a 

 natural animal system there are a few who have tried to abandon 

 the notion and the category of Coelenterata (Hyman, Bekle- 

 mischew, Perrier, Dudich, etc.). Here we are able to mention a 

 few such cases only. Such authors have usually gone back to the 

 old notion and name of Radiata or Radiaha, excluding from 

 them Spongiae and Echinodermata. This was made for example, 

 by L. H. Hyman (she uses them as a contrast to Bilateria, 

 adding "Cnidaria [or] Coelenterata"); Beklemischew (1958) 

 divides Metazoa first into Enantiozoa (after Delage, for Pori- 

 fera) and Enterozoa; the latter are subdivided into Radialia 

 and Bilateria; Radialia, finally, consist of Cnidaria and Acnida- 

 ria. Dudich (1957) divides Eumetazoa into Acoelomata (i.e. 

 Cnidaria and Ctenophora) and Coelomata (Proto- and Deutero- 

 stomia). Dogiel (1947) takes over the old division into Diplo- 



