CHAPTEE VI 



CLASSIFICATION THE NINE ORDEES OF INSECTS THEIR CHARACTERS 



PACKARD'S ARRANGEMENT BRAUER'S CLASSIFICATION 



CLASSIFICATIONS BASED ON METAMORPHOSIS SUPER-OKDEKS 



THE SUBDIVISIONS OF ORDERS. 



Classification. 



"VYe have already alluded to the fact that Insects are the most 

 numerous in species and individuals of all land animals : it is 

 estimated that about 250,000 species have been already described 

 and have had scientific names given to them, and it is considered 

 that this is probably only about one-tenth of those that really 

 exist. The classification in a comprehensible manner of such an 

 enormous number of forms is, it will be readily understood, a 

 matter of great difficulty. Several methods or schemes have 

 since the time of Linnaeus been devised for the purpose, but we 

 shall not trouble the reader to consider them, because most of 

 them have fallen into disuse and have only a historical interest. 

 Even at present there exists, however, considerable diversity of 

 opinion on the question of classification, due in part to the fact 

 that some naturalists take the structure of the perfect or adult 

 Insect as the basis of their arrangement, while others prefer to 

 treat the steps or processes by which the structure is attained, as 

 being of primary importance. To consider the relative values of 

 these two methods would be beyond our scope, but as in practice 

 a knowledge of the structures themselves must precede an inquiry 

 as to the phases of development by which the structures are reached ; 

 and as this latter kind of knowledge has been obtained in the 

 case of a comparatively small portion of the known forms, — the 

 embryology and metamorphosis having been investigated in but 



