52 STRUCTURAL AND SYSTEMATIC ZOOLOGY 



Family, Branch, and Series. To Linnaeus we are also 

 indebted for a scientific method of naming animals. 

 Thus, the dog, in Zoology, is called Cam's familiaris, 

 which is the union of a generic and a specific name, 

 corresponding to the surname and the Christian name 

 in George Washington, only the specific name comes 

 last. It will be understood that these are abstract 

 terms, expressing simply the relations of resemblance ; 

 there is no such thing as genus or species. 



Classification is a process of comparison. He is the 

 best naturalist who most readily and correctly recog- 

 nizes likeness founded on structural characters. As 

 it is easier to detect differences than resemblances, it 

 is much easier to distinguish the class to which an ani- 

 mal belongs than the genus, and the genus than the 

 species. In passing from species to classes, the charac- 

 ters of agreement become fewer and fewer, while the 

 distinctions are more and more manifest; so that ani- 

 mals of the same class are more like than unlike, while 

 members of distinct classes are more unlike than like. 



To illustrate the method of zoological analysis by 

 searching for affinities and differences, we will take 

 an example suggested by Professor Agassiz. Suppose 

 we see together a dog, a cat, a bear, a horse, a cow, and 

 a deer. The first feature which strikes us as common 

 to any two of them is the horn in the cow and the deer. 

 But how shall we associate either of the others with 

 these ? We examine the teeth, and find those of the 

 dog, the cat, and the bear sharp and cutting ; while 

 those of the cow, the deer, and the horse have flat sur- 

 faces, adapted to grinding and chewing, rather than to 

 cutting and tearing. We compare these features of 

 their structure with the habits of these animals, and 

 find that the first are carnivorous that they seize and 

 tear their prey; while the others are herbivorous, or 



