1(0.1331. 



DRAGON-FLY WING VENATION— NEEDHAM. 



739 



Fetalurma:'. — The type of venation presented by this singular group 

 Parallels, rather remotely, the Libellulid^e in the behavior of the anal 

 j/ein, shifting- as it does upon the second cubito-anal cross vein to brace 

 bhe antero-internal angle of the triangle in the fore wing, retaining a 

 more direct course to the hind angle in the hind Aving. It parallels 

 the fossil Stenoj)hleUa in the curvature of the wing outlines, tending 

 bward a somewhat sickle-shaped wing apex. The very peculiar, nar- 

 rowly linear stigma is directly correlated with the wing form. It will 

 ije observed in the genera TJropetala (fig. 4, .y) and Phenes, in which the 

 bostal space is most narrowed and the stigma most curved and elon- 

 gated, the brace vein has 

 nigrated away from the 

 ■^tigma toward the nodus. 

 Tn this group the anal loop 

 .IS often not well dift'eren- 

 pated (fig. 28). Except- 

 ■mg at the base of the 

 ivving, reduction of cross- 

 'reins has not been carried 

 ver}" far. Tachoi^teryx 

 hagenl (fig. 29) seems to 

 be the most generalized 

 living member of the 

 ^roup (compare with Plate 

 XXXVI, fig. 1). It will be 

 observed this one is most 

 like the Gomphina?, the 

 subfamily which is doubt- 

 less nearest akin. The 

 g-roup is a veiy small one, 

 apparently on the wane. 



It is well represented 

 among the Tertiary fossils 

 of Europe. Of living spe- 

 cies there is one in the eastern United States, one in Nevada, one in 

 Japan, and there are several each in Chile and the Australian region. 



B. Lihellulidse. — This famil}^, unlike the JEschnidje, exhibits a single 

 type of venation, whose dominant tendency is toward the differentia- 

 tion between the wings, by means of the procession of the triangle, and 

 the switching of the anal vein in the fore wing, and in the hind wing 

 the recession of the triangle and the elongation of the anal loop. 

 The stigma is never braced, and the bridge remains shorter than in 

 the -^schnidfe, with fewer included cross veins. 



Macro))iiu}£e. — Members of this group (Plate XLI, figs. 1 and 2) 

 have followed these tendencies a little wav, and have then gone off on 

 Proc. N. M. vol. xxvi— 02 50 



Fig. 28. — Bases of wings of Petalura gigantea Leach, and 

 X detail fkom the region of the nodus, showing the 



BRIDGE WITH TWO OBLIQUE VEINS, O' AND O. 



