APPENDIX 



Chart I shows the great divisions of the ani- 

 mal kingdom into subkingdoms or phyla, and 

 their subdivisions Into classes. These are here 

 presented in artificial tabular arrangement. 

 After each class stands the name of one of its 

 most common or familiar representatives. 



The classification of vertebrates might well 

 have been carried farther. The subdivisions of 

 the fishes which Interest us are the orders of 

 sharks and ganoids. The latter order is illus- 

 trated by the sturgeons and gar pikes. The only 

 amphibia which concern us are the very oldest, 

 the extinct Stegocephala. The ancient and ex- 

 tinct theromorphous reptiles were probably the 

 ancestors of mammals. Among mammals the 

 duckbill and Echidna are the last surviving egg- 

 laying forms. The marsupials are represented 

 by the kangaroo and other Australian forms. 

 Above these stand the placental mammals, in 

 which the embryo Is nourished by the placenta, 

 which absorbs nutriment and oxygen from the 



2IO 



