356 



ANIMAL AGGREGATIONS 



than special biological significance? Chart I gives a diagrammatic 

 list of the portions of the animal kingdom in which this principle of 

 automatic co-operation has been demonstrated to date. 



CHART I 



DiPHYLETic Tree, of Relationships within the Animal Kingdom* 



Birds Mammals 



Insecta 



Cephalochordata 

 Urochordata 

 Hemichordata 



CHORDATA 



kingdom 



PROTOPHYTA 



Primitive plants 

 / 

 PRIMITIVE PLANT-ANIMAL 



'■ Phyla are given in larger, classes in smaller, capitals. 



