52 ECONOMIC ZOOLOGY AND ENTOMOLOGY 



bine the species name word, which may be used repeatedly, 

 that is, used for several different species, with the name of 

 the genus to which the species belongs, and thus make a two- 

 word name, or "binomial," for each animal kind. These 

 two-word names distinguish the species unmistakably from 

 each other because although the same word, familiaris, may 

 be used for several or even many different species it is never 

 used for more than one species in any given genus, and the 

 genus name is never used for more than a single genus. So 

 that Canis familiaris, the scientific two- word name for the dog 

 species, unmistakably distinguishes the dog by name from 

 all the other half million species of animals we know. There 

 might be a Merula familiaris, or a Musca familiaris in the list, 

 but not a second Canis familiaris. You will have noticed 

 that we have capitalized the first or genus word in the two- 

 word scientific name of the dog, but not the second or species 

 word. And this is the rule in zoological nomenclature. Even 

 if the species word is derived from a proper name, as is often 

 the case, it is not capitalized. The botanists do not adhere to 

 this rule, so that they might write Canis Browni, if Canis were 

 the genus name of a plant and Browni the species name. 



Just as there are often several and sometimes many species 

 sufficiently alike, or better, closely enough related, to be 

 grouped together into one genus, so there are usually several 

 or many genera related closely enough to be brought together 

 into a group of a higher or more comprehensive degree. There 

 are, for example, other genera of animals showing unmistakable 

 affinities, by their resemblances of structure, with the dog and 

 wolf genus Canis. Such for example are the genera Vulpes 

 and Urocyon which include various species of foxes. These 

 related genera are then grouped together to form a family; in 

 this case the family Canidce. Note that the proper name of 

 this family is made by adding idee to the stem part of the name 

 of one of the genera in it. That is, the name of an important 

 genus in the family is taken in the genitive case and pluralized 

 in order to make the family name. And this is a general rule 

 in zoological nomenclature. 



Related families are grouped together to form orders. 



