THE NEW GENEALOGICAL TREE 429 



Ameria. In the Echinodermata a secondarily emerging pro- 

 gressive trend is most clearly noticeable; this has been the 

 reason why the Echinodermata have been treated so frequently 

 by the systematists as a special type or as a phylum. The 

 Echinodermata had developed, apart from a hypodermic 

 skeleton, new systems of coeloms and special organs of move- 

 ment also which are a consequence of their secondarily acquired 

 free mobility. The Echinodermata certainly represent the 

 cUmax reached in the progressive evolution within the phylum 

 Oligomeria. They have even become indirectly able to repro- 

 duce asexually by way of an intensified regenerative ability. 

 They also show a conspicuously rich development of various 

 subtypes, many of these have died long ago. 



Among the sessile Oligomeria we notice a progressive 

 evolution in the Ectoprocta too. Yet as regards the condition 

 reached in the organization of their individuals (we can speak 

 here almost of subindividuals) they have preserved a 

 low level, or they had sunk in this respect to an even lower 

 level. A progressive trend can be observed in the formation 

 of their cormi (colonies) which are frequently regularly built 

 and polymorphous. 



There are not less than six classes of the Oligomeria, i.e. 

 Sipunculoidea, Phoronidea, Pogonophora, Brachiopoda, Chae- 

 tognatha, and Pterobranchia which all include a few species 

 only (only the Brachiopoda possessed numerous species 

 during their geological history), which represent "insig- 

 nificant" side branches of the evolution that are of little use 

 in our phylogenetic speculations, and which do not play any 

 significant role in the life of the sea. 



Special attention must be paid to the class Enteropneusta 

 even if this class does not appear very important from the 

 ecological viewpoint or with regard to the number of species it 

 includes or the living mass. The species which belong to this 

 class (ca. seventy-five) are some of those Oligomeria which had 

 partly won the ability to move freely ; they are therefore 

 semi-sessile animals which do not live in tubules built by 



