PREVIOUS INTERPRETATIONS OF CNIDARIA 



95 



Fig. 18. Aberrant benthonic narcomedusa: Otohydra vagans Swed- 

 mark & Teissier, with preserved otocysts; A, side-view, B, oral- 

 view, (After Swedmark and Teissier.) 



Dollo's rule (which was proposed, according to L. Cuenot, 

 first by Edgar Quinet, [1870]) does not seem to be valid for 

 individual characteristics which are probably due to the 

 mutation of a single gene. We can conclude, as a result of 

 this discussion, that without any doubt the polyp form is 

 the primitive, the initial form in all Cnidaria, and that this 

 form has been secondarily developed into the medusa form. 

 Later we shall try to show how this development took place 

 twice and independently from each other. 



The Right Sequence of the Cnidaria Groups 



The second major problem we meet in our study of Cnidaria 

 is whether we should arrange the three generally accepted 

 subgroups of Cnidaria which have been given the title of 

 classes, as one after the other, i.e. Hydrozoa— Scyphozoa 

 -Anthozoa, or conversely. It should be remarked in passing 

 that repeated attempts have been made, particularly by 



