582 



ZOOLOGY 



SECT. XIII 



In accordance with these conclusions the mutual relationships 

 of the phyla may be expressed in a diagrammatic form as 

 follows : 



CHORDATA 



ARTHROPODA 

 MOLLUSCA 



MOLLUSCOIDA 



TROCHELMINTHES 

 \ 



NEMATHELIVHNTHES 

 \ 



PLATYHELMINTHES 

 X, 



COELENTERATA 



ECHINODERMATA 



PORIFERA 



11 

 3 3 



s*. 



1 



PROTOZOA 



;i 



FIG. 1169. Diagram illustrating the Mutual Relationships of the Chordata. 



