50 Joh7i Henry Comstock 



study of every structure that has been developed in these in- 

 sects. 



But although this extended study will be necessary before 

 we can consider our work complete, a provisional classification 

 can be based on the study of a single organ or set of organs. 

 We have only to remember that such a classification is merely 

 provisional, and that the results obtained in this way should 

 be confirmed or corrected by the study of other organs. 



Following the method indicated, the wings were selected as 

 the first organs to be studied. These organs were chosen as 

 the most available ones, owing to their size, and the ease with 

 which variations in their structure could be observed. The 

 record of the action of natural selection is recorded upon 

 them as upon a broad page. For a long time my attention 

 was confined to the wings of the Lepidoptera. But later I 

 found it necessary to greatly extend my studies in order to 

 determine the primitive type of the wings of insects. It was 

 also necessary to study the wings of insects of other groups in 

 order to select a nomenclature of the wing veins that would 

 apply to all orders of insects. 



Although there are great differences in the venation of the 

 wings of insects of different orders, a study of the more gen- 

 eralized members of the several orders of winged insects show 

 that the type of venation is the same for them all. This indi- 

 cates two points of great scientific interest : first, wings have 

 originated but once in the class Hexapoda, or, to state the 

 same thing in other words, all of the orders of winged insects 

 have descended from a common stock ; second, if all the 

 various forms of wings are modifications of the same type, it is 

 not too much to expect to be able to establish a uniform no- 

 menclature for the principal elements in the frame work of 

 the wings, i. e., the principal veins, although doubtless it 

 will be necessary to use special names in many cases for 

 structures that have been developed secondarily. 



The importance of the wings of insects for taxonomic pur- 

 poses was early recognized by entomologists, as is well shown 

 by the fact that the names of the Linnean orders are all 

 drawn from the nature of the wings, except one, Apiera, and 

 that from the absence of wings. 



