THE NEW GENEALOGICAL TREE 



427 



zoa which show an impoverished or reduced segmentation 

 (yet not individual species !) into a large group which we call 

 the Oligomeria. We think that this large group actually repre- 

 sents the natural facts. Here we include those groups 

 which do not show a clear segmentation of the perigastrocoele, 

 as well as those which have three pairs of the perigastrocoele. 

 The following nine classes are therefore included in the phylum 

 Oligomeria: 



(1) Sipunculoidea. 



(2) Phoronoidea. 



(3) Pogonophora. 



(4) Brachiopoda. 



(5) Chaetognatha. 



(6) Ectoprocta. 



(7) Echinodermata. 



(8) Pterobranchia. 



(9) Enteropneusta. 



Chordoma 



Enteropneusta^ 

 Oligomeria 

 Pterobranchia 



...... 



Sipunculoidea 



/^Echin odermata 

 / A Ectoprocta 



I / /Chaetognatha 

 l*!/ / ^Brachiopoda 



ii// . 



\\l / y Phoronidea 



Annelida 

 (Polymeria) 



Fig. 58. Genealogical tree of the phylum: Oligomeria. 



The phylum Oligomeria consists thus of nine classes which 

 usually represent few species only, in comparison with the 

 fifteen classes that belong to the Ameria, and the eight classes 

 which belong to the Polymeria (Fig. 58). There are two 

 classes only of the Oligomeria which represent a larger number 



