OUTLINES OF ENTOMOLOGY. 23 



CHAPTER VII. 



CLASSIFICATION AND NAMES OF INSECTS. 



Having in preceding chapters considered the characters by which, 

 insects are distinguished from all other animals, we shall now proceed 

 to notice those by which they may be distinguished from each other. 



As a preliminary to such observation it will be a good plan for the 

 student to collect for an hour or two in various situations — field, wood 

 and water-courses — all the insects that he can find. When these are 

 examined he will perceive at a glance that they are not all alike — that 

 they differ in form, size, color, and in many points of structure. He 

 may then proceed to assort them, placing together those that appear 

 to be exactly alike. The next step will be to compare the different 

 lots, when it will be found that several of these closely resemble one 

 or more of the other lots, and such may be arranged side by side. 

 Still other combinations may be made with these compound groups, 

 until finally the entire collection will be embraced in a few comprehen- 

 sive assemblages. These groups may be considered to represent Spe- 

 cies, Genera, Families and Orders. 



Classification consists in a systematic arrangement of specimens 

 according to their place in each division, thus showing their near and 

 their remote relationships. By means of it we are enabled to consider 

 a multitude of organic forms under a few general heads. 



A Species comprises all individuals that are supposed to have had 

 a common parentage, and are exactly alike in all essential points of 

 structure and habit. 



A Genus ( plural genera) is an assemblage of species that are not 

 the same in all particulars, but have more points of resemblance than 

 of difference. 



The characters upon which genera are based are different in the 

 different families of insects, and even concerning insects in the same 

 family the opinions of entomologists differ as to what constitutes a 

 character of generic value. 



A Family includes all the genera that have in common a few impor- 

 tant peculiarities of form and habit. 



A Tribe is an assemblage of families whose relationship, thougk 

 remote, is inferred from the similar structure of a few organs. 



An Order includes all these groups and is founded upon agreement 

 in general structure and mode of development. 



