634 PROCEEDINGS OF THE NATIONAL MUSEUM. voi. xxix. 



family represents a series in which the anal veins have been modified 

 before the loss of the radial cross- vein. In this subfamily the costal 

 area is broad with the free part of Sc^ distinct. The area between Rj 

 and R, is ver}" broad, the radial cross-vein is long, straight, and 

 slightl}" oblique. The area between the base of the stigma and the 

 base of the radial sector has been chitinized so that it appears as a 

 part of the stigma. The medio-cubital cross-vein is joined to R+M 

 distinctl_y before the origin of media, usually near the free part of Scj. 

 The free part of M^-j-Cui is joined to the cell M^ near its middle. 

 The anal cells are contracted for a short distance in iroplocam.jxi and 

 for a considerable distance in Ilemichroa. In the hind wings the anal 

 lobe is larger, the venation is of the usual type. 



Diiieurinse. — This subfamily as generally limited contains the genera 

 Dineura (fig. 63) and Meson eiira (tig. H4). To these has been added 

 the genus Pseudodhieura (tig. 65), which is closeh" allied to thenj. 

 The Dineurina? are quite similar in wing type to the preceding sub- 

 family, the most notable diti'erence is in the loss of the Ijase of the third 

 anal vein, so that the cell included between 1st A+2d A, and 3d A 

 has coalesced with the third anal cell. There is a notable variation 

 in the amount of thickening of the apex of the costa, the greatest 

 thickening being found in the genus Mes<meura. The free part of 8c, 

 occupies a different position in each of the genera; in Meson euro it is 

 about its own length before the medio-cubital cross-vein, in Psetidodi- 

 neura it is almost interstitial with the cross-vein, and in Dineura it is 

 about its own length beyond it. The position of the free part of Sc, 

 is usually of but little value systematically, at least in certain groups. 

 This is marked in Pteronas ventralix^ one of the Nematinae, where this 

 vein is not constant within a single species, but may in different indi- 

 viduals occupy all three of the positions described for the genera of 

 this subfamily. In Pseudodineitrd the apes' of the free part of the 

 second anal vein is wanting. The hind wings are of the usual type. 



Moiiocteninse. — Beginning with this subfamily there is a series of 

 three closely related subfamilies in which the loss of the radial cross- 

 vein has preceded the modifications of the anal veins. The Monoc- 

 tenina' contains a single genus, Monoctenx.s (tig. 67), which all sys- 

 tematists have agreed hitherto in associating with the genus. Lop hyr us 

 (fig. 45), described above. Monocfenus is like Zo/>/!///v/.v in lacking the 

 radial cross-vein and in having the costal area ))road, with a prominent 

 free part of Sc,. In Monoctenus the costa is slightly thickened at apex; 

 the medio-cu])ital cross-vein is joined in the angle between R and M; 

 this cross-vein and the stem of M..^+^ are divergent behind; the anal 

 cells are broadly anastomosed at middle; the free part of M^+Cu, joins 

 the cell M^ near its middle and is strongly oblique; the cell Rj+g is 

 broad and pointed at apex, and the area between the base of the stigma 

 and the radial sector is distinctlv chitinized. in the hind wings the 



