784 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXV 



dant cross veins, and the strengthening- of the principal veins and In-ace 

 seem to have been the means whereby these wings have attained thei 

 goodl}' measure of efficiency. 



yEschiiyirV. — We come now to a g-roup that is floarishing in our ow 

 time the woi'ld over. It contains the largest of our common drao-oi 



Fig. 25.— Wings of CorduUgastcr sai/i Selys. 



flies, all strong-flying species, composing many genera. In the mor< 

 specialized genera are many species. There is great variety in th( 

 details of the luxuriant venation of the group. Here, then, we hav< 

 opportunity to apply the facts of development pre\'iously outlined t( 

 the unravelling of a bit of genealogic history. 



Fig. 2(>.— WING.S OF Phyllopctalia apicalis Selys. 



The most characteristic features of the ^Eschnine wing are (1) the 

 approximation of veins 3f^ and M^, brought about by the bending 

 forward of vein M, at the stigma, (2) the development of strong and 

 broadly curved supplements, and (3) the elongation of the triangles in 

 the direction of the axis of the wing. These will be seen in their best 

 development in such genera 'dSu£schna and Ana.v (Plate XL.) 



