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BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [8] 



CLASSIFICATION OF HEXAPODS. 



Seven orders of insects were originally recognized by Linnseus, namely, 

 Neuroptera, Diptera, Hemij)tera, Lepidoptera, Ooleoptera, Hymenoptera, 

 and Aptera. This classification was based on the organs of flight only, 

 and while in the main resulting in natural divisions which still furnish 

 the basis of more modern classifications, was faulty in several particu- 

 lars. For instance, the Aptera, which included all wingless insects, was 

 soon found to be a very unnatural assemblage and its components were 

 distributed among the other orders. The establishment of the order 

 Orthoptera by Olivier to include a large and well-defined group of in- 

 sects associated with the Hemiptera by Linnaeus, restored the original 

 seven orders, and this classification has, in the main, been followed by 

 entomologists up to the present time. 



HTMENOPTEEA, Linn. 



COLEOPTEBA, Aristotle./ 1^ 

 Strepsiptera, Kirby. 



ORTHOPTEEl, Oliv 

 Euplexoptera, West.|^ 



Trichoptera, Kirby 

 NEUBOPTEBA, Linn./, 



Dictyotoptera , Burm./^ 

 T%y$anoptera , Haiiday 



B\LEPIDOPTERA, Lmn. 



raHEMIPTERA, Linn. 

 <ii\Homoptera, MacLeay. 

 DIPTERA, Aristotle. 



^XAplianiptera , Kirby. 



o 



Fig. 1. — Pyramid sliowing the nature of the mouth, and relative rank of 

 the Orders, and the affinities of the Sub-orders of Insects. 



All insects are, in a broad way, referable to one or the other of these 

 seven j^rimary orders by the structure of the wings and the character of 

 the mouth-parts in the imago, and by the nature of their transformations. 



Some of these orders are connected by aberrant and osculant families 

 or groups, which have by other authors been variously ranked as inde- 

 pendent orders, but which, following Westwood substantially, I have 

 considered, for convenience, as suborders. {See Fifth Eeport, Insects 

 of Missouri, etc., 1872.) 



In the article just cited, I made use of the accompanying diagram in 

 the form of a pyramid (Fig. 1), which gives a graphic representation of 

 the distinguishing characters and the relative rank as usually accepted, 

 of the orders and suborders. 



Full discussion of the different classifications is unnecessary in this 



