1 8 ANIMAL BIOLOGY 



venient to give every human being a name. The name of 

 each species of animal or plant commonly consists of 

 two words, the first designating the genus, the second the 

 species. The Rocky Mountain locust is named Mela- 

 no plus spretus, Melanoplus being the genus and spretus 

 indicating a particular species of that genus. The red- 

 legged grasshopper is closely related to this species and is 

 therefore placed in the same genus but given a different 

 species name, Melanoplus femur-rubrum. The various 

 species of bears mentioned are members of the genus Ursus 

 which is the Latin name for bear; the grizzly bear is called 

 Ursus horribilis; the common black bear, Ursus ameri- 

 canus; and the European brown bear, Ursus arctos. The 

 naming of species of animals is very much like naming 

 different people John Jones, Peter Jones and Mary Jones 

 to indicate that they are individuals of the Jones family. 

 Just as similar species are grouped into genera so are 

 allied genera united into a larger group, the family. 

 Melanoplus, Dissosteira or the genus of the roadside 

 grasshopper, and other related genera are grouped into 

 the family Acridiidae which includes the short-horned 

 grasshoppers. Similarly various families such as the 

 long-horned grasshoppers and katydids which constitute 

 the family Locus tidae; the cricket family, Grillidas; the cock- 

 roach family, Blattidae, etc., are grouped into a larger divi- 

 sion, or order, called the Orthoptera (orthos, straight, and 

 pteron wing). The order Orthoptera, together with other 

 orders such as the Coleoptera or beetles, the Diptera or 

 flies, etc., constitute the class of Insecta. And the Insecta 

 together with other classes such as the Crustacea (crayfish, 

 crabs and their allies) and the Arachnida (spiders, scor- 

 pions, mites, etc.) and some others are united to form a 

 still larger division called phylum, which is the largest 

 subdivision of the animal kingdom. The vast assemblage 



