NO. 1331. 



DRAGON-FLY WING VENATION— NEEDHAM. 



743 



The support for the expanded area developed upon vein (7^2, which 

 was set off from vein Cii^ liy a long- posteriori j'^ directed stalk; sec- 

 ondaiy branches developed upon the posterior jside of vein 6Vo radiating 

 to the wing margin. The anal vein did not join vein Ou.,. The stigma 

 was unbraced, and the wings were decurved at the tips, much as in the 

 Petal urinie. 



Among living Calopterygida? the tendency has been to match cross 

 i veins in lines parallel with the veins, thus producing a large number 

 'of interpolated sectors between the principal veins. This has been 

 'carried so far that few vestiges of the primitively hexagonal form 

 of the cells remain. This has facilitated (perhaps we should sa}' has 

 • accompanied) the throwing 

 ' of the wing membrane into 

 longitudinal furrows, and we 

 find the sectors, in some 

 forms, alternately convex 

 and concave even to the dis- 

 tal margin of the wing. In 

 those forms in which the 

 furrowing of the membrane 

 is most general we tind the 

 least tendency toward re- 

 duction of cross veins. Per- 

 haps the fanlike folding of 

 the membrane enabled it to 

 resist bending and rendered 

 unnecessary the differentia- 

 tion of stronger veins for 

 that purpose. 



EpaUagin ». — This group 

 comprises the more general- 

 ized living members of the 

 family, especially in the Le- 



-BASE (IF WINGS OF Ix(,ii),\( pia (FOSSII.) IN PART 

 AKTEE DeICHMOIJ,EK. 



gion Euphwa of de Selys, 



wherein the nymphs, so far as known, have paired gill filaments along 

 the sides of the abdomen and have biramous mandibles. In this group 

 the media tends to descend to the middle of the arculus, the nodus to 

 recede moderately toward the base of the wing, and the quadrangle to 

 lose the dividing cross vein. The quadrangle behaves similarlv in both 

 fore and hind wings. Pseudopltsea seems, on the whole, as primitive 

 as any genus of the group (tig. 32). Rhinocypha and its allies (Plate 

 LII, tigs. 1, 2, and 5) constitute a short lateral series. De Selys long- 

 ago showed, from characters not drawn from the wings, that they 

 constitute a distinct suliordinate group, but he did not point out the 

 venational characters in which they are peculiar. These will be dis- 



