372 BIOLOGY 



clear that the wild cat and domestic cat show greater resemblances 

 to each other than they do to tigers, dogs, or wolves. Moreover, 

 it is evident to anyone in the slightest degree familiar with ani- 

 mals, that lions, tigers, leopards, wild cats, and domestic cats, 

 although unlike each other, and recognized by naturalists as 

 belonging to different species, have many points of resemblance 

 to each other. They have the same general stealthy habits, 

 the same kind of toes and feet, and they are much more closely 

 allied to each other than any one of them is allied to the 

 dog or the wolf. Naturalists, therefore, group all of these 

 species together under one group which they call a genus (pi. 

 genera). 



In naming any species, two names are commonly used, the 

 first of which is the name of the genus, the second that of the 

 species. For example, Felis is the name given to the whole genus 

 of cats. Felis domestica is the domestic cat; Felis leo is the 

 lion; Felis bengalis, the bengal tiger; Felis canadensis, the Ca- 

 nadian lynx, etc. So, too, Viola is the genus name of all the 

 violets; Viola blanda, of the white violet; Viola cucullata, of 

 the common blue violet, etc. If the species should happen to 

 have more than one variety or sub-species, a third name may 

 sometimes be added to indicate the particular variety of the 

 species. As a rule, however, two names only are used. 



Families. Extending observation a little farther, it becomes 

 evident that many genera show close resemblances which mark 

 them off distinctly from other animals. As a result, naturalists 

 group genera together into a larger group, which they call a 

 family. A family sometimes may contain only a single genus; 

 it may contain two or three or a large number of genera. 



Orders. In the same way, families are grouped together to 

 form larger groups, which are called orders. For example, the 

 various cats already considered have certain points in common 

 with the dogs, wolves, bears, seals, and walruses. In all of these 

 cases the teeth are especially adapted for cutting flesh, and the 

 animals are flesh eaters. There are very many genera among 



