72 ELEMENTARY ZOOLOGY 



belongs, while the second or species word distinguishes it 

 from the few or many other species which are included in the 

 same genus. This manner of naming species of animals 

 and plants (for plants are given their scientific names 

 according to the same plan) was devised by the great 

 Swedish naturalist Linnaeus in the middle of the 

 eighteenth century and has been in use ever since. 



Family. Examine a red-headed woodpecker (J^lela- 

 nerpes crytJirocepJialus) and a sapsucker (Spliyrapicus 

 varius) and any other kinds of woodpeckers which can be 

 got. Find out in what ways the hairy and downy 

 woodpeckers (genus Dry ob cites), the flickers (genus 

 Colapies) and the other woodpeckers resemble each other. 

 Examine especially the bill, feet, wings and tail. These 

 birds differ in size, color and markings, but they are 

 obviously all alike in certain important structural respects. 

 We recognize them all as woodpeckers. We can group 

 all the woodpeckers together, including several different 

 genera, to form a group which is called a family. A 

 family is a group of genera which have a considerable 

 number of common structural features. Each family is 

 given a proper name consisting of a single word. The 

 family of woodpeckers is named Picidce. 



We have already learned that resemblances between 

 animals indicate (usually) relationship, and that classify- 

 ing animals is simply expressing or indicating these 

 relationships. When we group several species together 

 to form a genus we indicate that these species are closely 

 related. And similarly a family is a group of related 

 genera. 



Order. There are other groups* higher or more com- 



*Each of these higher groups has a proper name composed of a single 

 word. In the case of no group except the species is a name-word ever 

 duplicated. Each genus, family, order, or higher group has a name-word 

 peculiar to it, and belonging to it alone. 



