NEW INTERPRETATION OF CNIDARL\ 245 



the necessarv abolition of the notion Radialia (or Radiata) we 

 must also abandon the opposite notion of Bilateria. The 

 structure of all Eumetazoa was originally bilaterally symmetric 

 and it was secondarily only, usually as a consequence of a 

 prolonged sessile way of life, that they have developed a more 

 or less explicit inclination to the radial symmetry. 



Each change of the animal system, especially when it in- 

 volves the higher systematic categories, is unwelcome and 

 scholars wiU therefore try to avoid it. Yet if we endeavour to 

 develop a natural system we are obliged to change this system 

 until it agrees with facts and with the interpretations that are 

 based on them. It is all the better if a simplification of this 

 classifacition appears as a result of our endeavours. 



Discussion of the New Interpretation of the 

 Evolution of Cnidaria 



The division of the taxon Cnidaria— regardless of the system 

 category which should be attributed to it— into the next lower 

 units, has been so firmly accepted by expert zoologists and by 

 others, in the sequence Hydrozoa ^ Scyphozoa -^ Anthozoa 

 that no attempt will be easily accepted which tries to change 

 this sequence. This is, in mv opinion, not only a consequence 

 of an otherwise healthy conservatism which suggests caution; 

 it is also due to the fact that the suggested change of a widely 

 accepted sequence has not been supported by a discovery 

 of, for example, a "Hving fossil," or at least by some 

 special new facts. The majority of zoologists have been influ- 

 enced even more by the consequences which this new inter- 

 pretation implies, than by the first two motives. 



In spite of the fact that the first pubHcation of my thesis 

 appeared as early as in 1944, the new sequence of the groups 

 of Cnidaria has not found acceptance, as far as I know, in 

 any manual or text book on neozoology. It should be re- 

 membered here that some palaeozoologists (Schindewolf, 1950; 

 17 



