INDIVIDUAL DIFFERENTIATION AND ADAPTATION. 103 



Other terms, as families, orders, classes, phyla, are used to 

 denote the still more extensive and comprehensive divisions 

 of the animal kingdom. 



139. Illustration of Classification. The domestic cat has 

 many varieties or breeds, as the maltese, manx, tortoise-shell, 

 etc. On the other hand, the wild-cat, the tiger, the leopard, 

 the lion have numerous points of -structural likeness to the 

 domestic cat, and are said to be species belonging to the same 

 genus (Felis}. The genus Felis and others less common are 

 placed together in the family Felidce. These with the members 

 of the dog family and others constitute the order Carnivora 

 (flesh eaters), and similarly for the higher groups in the 

 diagram below. 



Kingdom Animalia. 



Phylum Chordata (fishes, birds, mammals). 



Class Mammalia (carnivora, ruminants, bats, man). 

 Order Carnivora (dogs, wolves, cats, etc.). 

 Family Felidse (cat family). 



Genus Felis (cat, lion, tiger, etc.). 



Species Felis domestica (with its numerous 



varieties). 



The name of an animal is its generic name followed by its 

 specific name as above. The variety name is added when there 

 are distinct varieties. 



140. Relation of the Individual to the Species. The vari- 

 ous types of animals produce their offspring in numbers pro- 

 portional to the difficulties encountered in bringing the young 

 to maturity. In the most favorable circumstances many more 

 are produced than can survive. In cases where enemies are 

 numerous millions of eggs may be deposited in order to secure 

 a single adult. Nature is thus said to be lavish in her waste 

 of individuals in order that the species may be continued and 

 improved in its adaptations. These surviving descendants, 

 generation after generation, have become, through natural 

 selection, more and more suited to their surroundings. This 



