viii Preface 



of all of the orders of insects of which we could obtain living nymphs or 

 pupae. The results of this investigation were published in a series of 

 articles, entitled "The Wings of Insects," which appeared in the "American 

 Naturalist" during the years 1898 and 1899. 



Since the appearance of this series of articles, I have watched the prepar- 

 ation of many theses on the wings of insects, by students in the entomologi- 

 cal laboratory of Cornell University. The subject, therefore, has been 

 almost constantly in my mind throughout the greater part of my scientific 

 life. 



The series of articles published jointly by Dr. Needham and myself is 

 the most comprehensive discussion of the wings of insects in which I have 

 taken part ; and, consequently, in the writing of the following pages I have 

 copied freely from them. I am also under obligation to Dr. Needham for 

 continued assistance throughout the preparation of this treatise. 



Acknowledgments of assistance from other colleagues and students and 

 from published papers are given in the following chapters, where use has 

 been made of it. In this place I will refer only to some of the more impor- 

 tant of these contributions. 



The papers that had a bearing on the development of the uniform 

 terminology of the wing-veins that were published before the appearance of 

 the series of articles by Comstock and Needham in 1898 and 1899 are 

 enumerated in Chapter I, to which the reader is referred. 



The most extended use that has been made of the uniform tenninology 

 of the wing-veins is that of Handlirsch in his great work on fossil insects 

 ('o6-'o8). This work was the chief source from which I drew my con- 

 clusions regarding the paleontological evidence concerning the primitive 

 form of insect wings and the methods of their specialization that are given 

 in Chapter IV. 



Among the more important of the more special contributions to the 

 application of the uniform terminology of the wing-veins of insects are 

 those of Professor J. G. Needham on the Odonata, Miss Anna H. Morgan 

 on the Ephemerida, Professor W. D. Funl<:houser on the Membracidas, 

 Professor Z. P. Metcalf on the Jassidae, Fulgoridas, and Cercopidae, Miss 

 Edith Patch on the Psyllida;, Aphididae, Aleurodidas, and Coccidas, Pro- 

 fessor A. D. MacGillivray on the suborder Chalastogastra of the Hymenop- 

 tera, and Professor J. Chester Bradley on the Evaniidae. In addition to 

 this published paper by Professor Bradley, I have been permitted to study 

 a very extended manuscript on the venation of the wings of the H^-menop- 

 tera written by him. 



I have also made use of an unpublished thesis by Mrs. Ruby G. Smith 

 on the "Evolution of the Venation in the Anal Area of the Wings of Insects." 

 This thesis embodies the results of an investigation made under my direc- 

 tion, to test the correctness of the conclusions reached by Comstock and 



