570 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxix. 



I.— HISTORICAL." 



Students of wing-venation in the past almost invariably made the 

 mistake of considering the few-veined wing as the starting point and 

 the many-veined wing as the acquired condition. In the Lepidoptera 

 a wing-type like that occurring in the Noctuidfs or Arctiidge was con- 

 sidered the generalized condition, whih' the many- veined wings of the 

 Hepialida? and Micropteiygidje were looked upon as being at the sum- 

 mit of specialization in that ordei'. In the Diptera the wing of the 

 Muscidiv was taken as the starting point, and the extra veins found in 

 the Tabanidte and Leptida' were considered as entirel}" new develop- 

 ments and were given special names. The same view was held b}^ 

 writers on the Hymeno])tera, where a wing type similar to that found 

 in the SphecidcC was made use of. 



Our knowledge of the homology of the wing veins of insects is due 

 to the work of several investigators. The first one to consider this 

 subject was Hermann Hagen.'' He published a paper Ueber rationelle 

 Benennung des (leaders in den Fliigeln der Insekten, but this had 

 little more effect than to call attention to the importance of the sub- 

 ject. The first serious attempt to homologize the wing veins of 

 insects of all orders was not undertaken until sixteen years later when 

 Josef Redtenbacher'' pu]>lished a paper on a Vergleichende Studien 

 uber das Fliigelgeader der Insekten, which was an epoch-making work. 

 Unfortunately he made the serious mistake at the beginning of his 

 investigations of adopting the conclusions of Adolph; '' who, from a 

 study of the development of wing veins, had concluded that the veins 

 were, of two distinct kinds, concave and convex. The concave veins 

 had been produced by a thinning and the convex veins l>y a thickening 

 of the wing meml^rane; the former by a pushing in of the trachea, the 

 latter ))y the formation of chitinous lines and occupied l)y trachea? 

 only secondarily. Kedtenl)acher believed further that the wing was 

 longitudinally plaited, consisting of alternate ridges and grooves, the 

 concave or primary veins being situated at the bottom of the grooves 

 and the convex or secondary veins along the top of the ridges. He 

 considered that in the primitive insect the two wings of each side 

 were fan-like in form and similar in venation, like the wings of the 

 Saltatorial Orthoptera and Ephemeridge. Starting with such a manv- 

 veined type, he was successful in horaologizing the main stems of the 

 principal veins, but through his efforts to apply the theory of Adolph, 



«For extended bibliographies of pajiers dealing with the wing veins of insects the 

 following should be consulted: 



H. J. Kolbe. Einfiihrung in die Kenntniss tier Insecten. 1893. Pp. 269-271. 



A. 8. Packard. Text-book of Entomology. 1898. Pp. 147-148. 



6 Hermann Hagen. Stett. Ent. Zeit., XXXI, 1870, pp. 316-320. 



c Josef Redtenbacher. Ann. k. k. Naturh. Hofmus., T, 1886, pp. 153-232. 



f'G. Ernst Adolph. Ueber Insectentliigel. 1879. 



