112 ZOOLOGY 



tortoise-shell, etc. On the other hand, the wild-cat, the tiger, 

 the leopard, the lion, are species which have numerous points 

 of structural likeness to the domestic cat, and are said to belong 

 to the same genus (Felis) . . The genus Felis and others less 

 common are placed together in the family Felida. 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 (Protozoa, arthropods, chordates). 

 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. 



144. 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 laAdsh 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 selec- 

 tion of their variations, more and more suited to their surround- 

 ings. This means that the production of many individuals, a 

 large number of which never reach maturity, secures the devel- 

 opment of a small aristocracy which propagates the type. , The 

 species is related to its individuals something as the individual 

 is to the renewed and changing cells of which it is composed. 

 Species are not constant, but even the most fixed must undergo 



