618 



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 



\ 



NEMATHELMINTHES 

 .... ~~~\ 



PLATYHELMINTHES\\\ 



COELENTERATA 



PORIFERA 



PROTOZOA 



FIG. 1238. Diagram illustrating the Mutual Relationships of the Phyla. 



