572 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxix. 



and convex veins the concave veins are .secondary in orig-in, being 

 either luoditied convex veins or veins that have arisen de novo. The 

 concave veins having- arisen to meet two distinct needs — first, in those 

 insects whore the wings are ])i-oadly expanded so as to fit them for a 

 sliding flight there is a necessity for a plaiting of the wings when not 

 in use so as not to impede locomotion on foot; and second, where the 

 width of the wings has been greatly reduced to ht them for a rapid 

 vigorous liight and the wing-s have been corrugated so as to strengthen 

 them. The concave veins IV and VI, here named "premedia" and 

 '■'postmedia,'" respectively, w^ere considered as wanting not only in the 

 Lepidoptera. but also in the primitive insect's wing. They were con- 

 sidered to t)e present only in those highly specialized w^ing-s of modern 

 insects where a corrugation of the wing has arisen. The nomen- 

 clature of Redtenbacher was adopted in all details, except that the 

 branches of the veins were numbered consecutively^ with Arabic 

 indices regardless as to whether they were convex or concave. 



Packard," in 1895, g-ave an abstract of Spuler's paper mentioned 

 ai)ove, in which the nomenclature of Spuler is followed. Apparently, 

 if we may judge from his labeling of a notodontid wing, he has over- 

 looked one of the most important facts discovered b}^ Spuler, namely, 

 that the radius of the hind wings of the Lepidoptera consists of two 

 branches. 



In a Manual for the Study of Insects,'' pu])lished during the same 

 year, tho. homology of the wing veins in the orders Lepidoptera, Dip- 

 tera, and Hymenoptei'a was carefully determined and named in accord- 

 ance with the modihed Redtenbacher notation. The concave veins IV 

 and VI were shown to he wanting in these orders, but were supposed 

 to ])v present as secondary developments in those orders where the 

 fan-type of wing existed. 



In 1897 Comstock and Needham'' began jointl}' the publication of a 

 series of articles on the wings of insects of all orders. This investi- 

 g'ation was developed along two distinct lines and all the accessible 

 material of all the orders of winged insects was examined. First, 

 wherever possible, a careful study was made of the trachea which 

 precede the veins in the wing's of immature insects; and, second, there 

 was made a morphological comparison of the veins in the wings of 

 adult insects. The following important results were reached: 



First. That the concave veins IV and VI are wanting in the wings 

 of all insects. 



Second. That the primitive insect's wings had comparatively few 

 veins. These veins were eight in number. Beginning with the front 



«A. S. Packard. Psyche, VII, 1895, pp. 235-241. 

 ''J. H. and A. B. Coiiist(^ck. Itha(;a, N. Y., 1895. 



'J. H. Comstock and J. G. Needham. The Wings of Insects, Amer. Nat. 

 XXXII and XXXIII, 1898 and 1899. 



