1913] The Wing Venation of the JassidcB 107 



cross vein is attached to radius in some species of Scaphoideus 

 (Fig. 53) and in Typhlocyba (Fig. 77), but in Oncometopia the 

 resulting cross vein is sometimes absent in the adult wing, and 

 is sometimes present as a fairly strong cross vein uniting with 

 radius near the point where it branches into R2+3 and R4+5. In 

 other cases, it appears as a fairly strong cross vein distinctly 

 uniting subcosta with R2+3. The whole question seems to be 

 settled by reference to figure 3 which was taken from a half 

 grown nymph. This wing pad shows a weak Ri which runs 

 parallel to R2+3 for a considerable distance and then bends 

 toward the costal margin. All attempts to secure older nymphs 

 whose wing pads would show the forming veins along the 

 tracheae failed owing to the thickness of the pads and the large 

 amount of coloring matter. Inasmuch as trachea Ri does run 

 parallel with R2+3 for some distance it would seem to indicate 

 that the point of attachment of the cross vein which follows 

 the trachea might be at any one of various points along the 

 radial vein over a considerable length of that vein. 



In other cases this cross vein is very evidently R2. It 

 appears as a weak lateral branch of R2+3 in Parabolocratus 

 (Fig. 23), as a somewhat stronger branch in Goniagnathiis 

 (Fig. 25), as a still stronger branch in Phlepsiiis (Fig. 48). In 

 Acinopteriis (Fig. 41) the trachea gradually diverges but the 

 forming vein is set at nearly a right angle to R2+3. In Jassus 

 (Fig. 60) trachea R2 reaches its greatest size for any of the 

 genera examined and the vein in the adult wing seems to follow 

 the course of the trachea rather closely. In Chlorotettix (Fig. 43) 

 tracheae R2 and R3 are united for nearly their entire length, 

 being separated only at their tips. This character seems to be 

 comparatively constant for the genus (Fig. 52). In still other 

 genera the nodal cross vein is formed without being preceded by 

 any trachea. This is especially conspicuous in certain species 

 of Draeculacephala (Fig. 6) which have only one cross vein 

 connecting subcosta with R2-f3. In Eutettix (Fig. 46) two 

 cross veins are formed, one occupying the position of Ri and 

 the other the position of Ro. Neither one of these cross veins 

 is preceded by a trachea. There is an interesting question 

 involved in the genus Scaphoideus. As pointed out by Osborn 

 '00 the nodal vein arises from radius in auronitens and certain 

 other species while in jucundus and allied species it arises from 

 R2+3. Unfortunately the writer was able to secure nymphs of 



