MAN 



ORANG 

 GIBBON 



GORILLA 

 CHIMPANZEE 



EASTERN APE3 



CENTIPEDES 



CRUSTACEANS 



MOLLUSCS 



'COLONIAL FLAGELLATES 



IN FUSORIANS 

 ETC 



PRIMITIVE UNICELLULARS 



FIG. i. Tree illustrating the probable course of animal evolution. 



