A MANUAL FOR 



THE STUDY OF INSECTS. 



CHAPTER I. 



ZOOLOGICAL CLASSIFICATION AND NOMENCLATURE. 

 I. Zoological Classification. 



(For advanced students. ) 



IN order that the myriad forms of animals may be studied with 

 facility some system of classification is necessary. And now that we 

 have learned that there exists a blood-relationship between the differ- 

 ent kinds of animals, that system which most clearly expresses this 

 relationship is doubtless the best. This system is termed the Natural 

 Classification . 



It is now generally believed that long ago, in early geological 

 times, there existed on the earth only very simple animals and plants; 

 and that from these simple beginnings more and more complex forms 

 have been developed. This growth in complexity has taken place in 

 different descendants of these simple primitive beings in very differ- 

 ent ways. Thus while it is probable that the first animals lived in 

 water, and very many still do so, others have become adapted to life 

 on the land, and in still others organs have been developed by which 

 they can fly through the air. And under each of these conditions we 

 find a great diversity of forms, each fitted for some special mode of 

 life. 



