THE NEW GENEALOGICAL TREE 455 



Steiner does not mention my works which had appeared 

 before the publication of his treatise ; it is possible that either 

 he did not know them or that he did not consider them as 

 worthy of consideration. 



The Genealogical Tree of the Chordoma 



The mutual relationship connections that exist within the 

 phylum Chordonia among the tetrapod Vertebrata can now 

 be considered as sufficiently clarified; the same, however, can 

 not be said for the numerous lower groups of the Chor- 

 data, from the Acrania and up to the bony fishes. Since I 

 have not made my own researches in this field, I preserve 

 here the system of the Chordata that was suggested by 

 Vandebroek (1949) at the Xl^th International Congress of 

 Zoologists at Paris while at the same time I take into considera- 

 tion the progress which has recently been made in the field 

 of the paleozoology. If Tunicata had not existed we could 

 divide all the Chordonia into two superclasses, Pisces and 

 Tetrapoda; at the same time, how^ever, wx cannot recommend 

 a division of the Chordonia into three greatly unequal super- 

 classes, the Tunicata, Pisces, and the Tetrapoda. The term 

 Vertebrata which is generally so widely used, and which 

 will certainly continue to be used even if not as a taxonomic 

 notion, finds no place in the system proposed by Vande- 

 broek; neither can we find in this system the group Pisces 

 as a name of a class, or the Acrania and the Cyclostomata 

 (the former at least not as an independent class). 



The Tunicata should definitively follow the primitive 

 Chordonia, the Agnatha. There can be no doubt that the 

 Tunicata must be considered as Chordonia which secondarily 

 adopted the sessile way of Hfe. It can be said that this was the 

 last opportunity the animals have had to develop a sessile 

 group with all the consequences which we have so frequently 

 observed in the whole animal world, beginning with the 

 30* 



