2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 56 



I. INTRODUCTION 



When I began, some two years ago, to investigate intimately the 

 flying apparatus of the Diptera, I intended to make it a comparative 

 Study ; but, on obtaining an insight into the Hterature on the flying 

 organs of insects, I abandoned this idea because I found the neces- 

 sary foundation for a comparative work wanting: there does not 

 exist a single exact, perspicuous and well-illustrated description of 

 a Dipterous insect. I determined, therefore, to confine my studies 

 to a careful examination of the organs of flight in a single species. 



An examination of the literature of the subject showed me how 

 inexact the illustrations are and how difficult it is to use them to 

 any advantage in determining the parts of the actual object. From 

 the rough and almost useless drawings of Lowne (1890- 1895) to 

 the beautifully executed but quite schematic plates of Kunckel (1875- 

 1881), there is nothing that really approaches nature. 



In order to avoid the mistakes of my predecessors I made use of 

 photography for the graphic representations. This had not hitherto 

 been done, and indeed it seemed unlikely that it would be possible 

 to obtain good photographs of the thorax and wing-skeleton on 

 accotlnt of the yellow color of the chitin forming the hard parts, 

 and the apparent impossibiHty of obtaining sharp definition upon the 

 plate of all parts of such plastic bodies as are found in the skeleton 

 of the flying apparatus. 



After many unsuccessful attempts I finally succeeded, by means of 

 plates ("color") sensitive to yellow color and a Zeiss binocular, 

 in producing stereoscopic views true to nature in every particular 

 except that of color (see the section on material and methods of re- 

 search). Some schematic drawings, especially of muscles, were nec- 

 essary for further elucidation. 



The movement of the wings was studied by means of kymo- 

 graphic curves and serial photographic representations of Calliphora 

 vomitoria in the act of flight, made by Prof, von Lendenfeld. 



I abandoned my original intention to introduce a nomenclature 

 applicable alike to all higher insects, because I recognized that that 

 could properly be done only by means of very extensive studies in 

 comparative anatomy and embryology. I had, therefore, to content 

 myself with selecting from the names already in use those which 

 appeared to me most suitable ; such old appellations as were directly 

 contrary to the truth being replaced by new terms. At the same 

 time I allowed myself, especially in the designation of parts not 

 hitherto named, to be guided, as was F. Voss (1905), by the prin- 



