70 ELEMENTARY ENTOMOLOGY 



that it belongs to the genus Coccinella, to which this species and 

 many others belong, and which we recognize in this case as prob- 

 ably belonging to the family Coccinellidae, which we know to be a 

 family of predacious beetles of the order Coleoptera. 



Thus animals and plants are divided into the following succes- 

 sive groups : 



GROUP EXAMPLES 



Phylum (Arthropodd) 

 Class (Insect a] 



Order (Coleoptera} 



Family (Coccinellidae) 

 Genus (Coccinella) 



Species (novcmnotatet] 



Coccinella novemnotata Herbst. 



Species. The exact definition of a species has worried naturalists 

 since the time of Linnaeus and is still under dispute, so that no 

 exact definition will be attempted. It is evident that, inasmuch as 

 it applies to a large number of individuals, and as we know that 

 individuals vary exceedingly, it is largely a conception for our 

 convenience in designating forms of life. Inasmuch as we now 

 believe that all forms of life have had a common origin and have 

 been gradually evolved from one or at least a very few original 

 ancestors of all life during the millions of years of the earth's 

 history, and as we know that species of plants and animals are now 

 being formed, while others have disappeared from the earth, it is 

 evident that the species now being formed will be very similar to 

 each other and will be separated with great difficulty, if at all ; 

 whereas those species which have existed for a long period of time, 

 and whose nearly related species have disappeared, will be easily 

 recognizable and form very distinct species. In short, it may be 

 said that a species is an aggregation of individuals of so similar 

 a structure that they might all have been derived from the same 

 parent, whieh are more similar to each other titan to any other in- 

 dividuals, and which, when bred together, produce progeny of the 

 same degree of likeness, whieh will also be fertile and produce their 

 kind. The number of individuals in a species and their distribution 



