CNIDARIA AS THE ONLY COELENTERATA 23 



new animal types b}' way of neoteny. This scepticism, does not 

 seem to be justified in spite of the fact that not all such attempts 

 can be considered to have been very successful. New animal 

 forms — and not only new animal types— have in numerous 

 cases been developed by way of neoteny (cf. de Beer, 1958). 



Cnidaria as the Only Coelenterata 



Now that we have succeeded in isolating the Cnidaria, the 

 concept of the Coelenterata which has been so widely used 

 during the last hundred years has been reduced to one 

 group only. In this connection the question arises w^hether 

 it is still wise to continue to use this concept as well as the 

 name Coelenterata as opposed to Coelomata. The fact that 

 we have reduced the contents of the Coelenterata to a single 

 group, can certainly not be considered as sufficient to allow 

 us to question its existence. As a matter of fact, classifica- 

 tions can occasionally be found where "Coelenterata" ap- 

 pear in which Coelenterata are represented by the Cnidaria 

 only. It can be easily imagined that Coelenterata— considered 

 as a necessary stage in the evolution— are represented by one 

 subtype only, by Cnidaria. Yet in this case it would be necessary 

 to make it probable, if not proved, that the Cnidaria have deve- 

 loped as the first Eumetazoa from the Protozoa; a supposition 

 which again, if taken alone, could not be sufficient because 

 it would be necessary to show further that the next higher 

 animal group which, according to the present opinion, are 

 Tubellaria, have developed from the Cnidaria. 



I will try now to prove or to show it more probable that 

 the Cnidaria are neither the first (i.e. the lowermost) Eumeta- 

 zoa, nor the ancestors of the next higher developed Eumetazoa, 

 the Turbellaria. Since 1944,1 have defended this thesis and 

 supported it in numerous articles (Hadzi, 1946—1959.). The 

 fact that my book appeared during the Second World War 

 and in Slovene, a language of a small though progressive 

 3* 



