CHAPTER VIII 

 THE CLASSIFICATION OF ANIMALS 



The first thing one asks about an animal new to one's ex- 

 perience is, what is its name? It is really less the name itself 

 that we wish to know, than the information that this name 

 gives regarding the placing of the animal in some classificatory 

 relation with other animals. It is the classifying interest 

 that impels our question; and with most of us it is this interest 

 which in turn usually develops from a collecting interest 

 that first attracts us to the study of zoology. 



Meaning and Basis of Classification. However, if classify- 

 ing animals meant only arranging them in simple groups of 

 similar or dissimilar forms, and naming them, the classificatory 

 interest would deserve the reproaches so often heaped on it 

 by naturalists more interested in anatomy or physiology or 

 development. But classifying animals means much more 

 than that. Since the days of Darwin's "Origin of Species," 

 when the theory of the evolution of animals and plants was so 

 clearly explained and proved that the world could not help 

 but accept it as true, the classification of living things has had 

 a new and great importance. It has the importance of repre- 

 senting our knowledge of organic evolution, for the classifying 

 of animals and plants now means arranging them in groups 

 according to their descent. 



In the early days of the study of animals and plants their 

 classification or division into groups was based on the external 

 resemblances and differences which the early naturalists found 

 among the organisms they knew. But later when naturalists 

 began to dissect animals and get acquainted with the whole 

 body, the differences and likenesses of the inner parts, such 

 as the skeleton and organs of circulation and respiration, were 

 taken into account. For we know that animals which are 



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