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 



Fig. 123S. — Diagram illustrating the Mutual Relationships of the Phyla. 



