CLASSIFICATION OF ANIMALS 



547 



Verfebraf-cf 



Cephalochordafa 



Ari-hropodoi 



En f^(vpneus fa 



Annelida 

 Chaetognafha 



Nemerfineet 

 (CoelomFJ 



Nemafhelmin thes 

 (Boo/y Cavity) 



Plaf^helmin ihes 



Urochordata 



Mol/usca 



Echinoc/ermafof 

 (Secondary Radial) 



Brachiopoola 



Bryozoa 



True Coelom 



Cfenophora 

 (Biradial) 



Rofifera 

 (Body Cavily) 



Alimenfary Canal 



Bilateral Symmetry 

 Triploblastic 



Coe/enterata 

 (Radial) 



_Di£loblastic_ 



Porifera 

 (Radial) 



Plants 



First Life 

 Fig. 330. — Diagram of a phylogenetic tree illustrating one conception of the relation- 

 ship of the animal phyla, and also suggesting the uncertainty attending the relationship 

 of most of the different phyla above the Coelenterata. Levels of organization are indicated 

 by horizontal lines of dashes. Retrogression is suggested by the branch turning downward. 

 Enteropneusta is a class of Hemichordata which includes Balanoglossus. 



