110 Annals Entomological Society of America [Vol. VI, 



RADIUS OF THE HIND WING. 



The radius is typically two branched in the hind wing of the 

 JassidcB. Several mounts of Spangbergiella (Fig. 21) failed to 

 reveal anything but a single unbranched radial trachea. In 

 the adult hind wing (Fig. 35) there is faint indication of a vein 

 in the position usually occupied by R24-3. 



R2+3 reaches its greatest development in Draeculacephala 

 (Fig. 7) where it forms the tracheae that precedes the whole of 

 the ambient vein. In many forms, however, it is very much 

 atrophied (Figs. 24, 45, 47, 65) while in Empoasca (Fig. 67) the 

 radius is a simple unbranched trachea. The radius of the 

 Typhlocybidce coalesces for a considerable distance with Mi +2 

 (Figs. 65 and 67). 



MEDIUS OF THE HIND WING. 



Medius of the hind wing is two branched in all of the genera 

 that have been examined. In the Typhlocybidce, however, 

 Mi+2 coalesces with radius for some distance and M3+4 coalesces 

 with cubitus for almost its entire length so as to appear as a 

 cross vein in the adult wing connecting medius with cubitus 

 (Fig. 80). In the other genera studied M1+2 is connected with 

 R4+5 by a short cross vein and M3+4 is connected with cubitus 

 by a similar short cross vein. In some cases the latter cross 

 vein is greatly reduced and in Jassus (Fig. 69) R4+5 and M1+2 

 coalesce for a short distance and again separate before reaching 

 the margin of the wing. 



In all of the genera studied cubitus is a single unbranched 

 trachea in the hind wing. Its relations with medius in the 

 Typhlocybidce have already been discussed. As in the fore 

 wing, cubitus and first anal are very closely united. Second 

 and third anal are also present in nearly all cases and third anal 

 is frequently two branched. The second anal and the anterior 

 branch of the third anal generally coalesce for a considerable 

 distance near the middle of their course and are usually sepa- 

 rated again near the base of the wing (Figs. 16, 38, 57). There 

 is always a conspicuous fold just posterior to the anterior 

 branch of the third anal. 



HISTORICAL DISCUSSION. 



A comparison of the nomenclature here suggested with the 

 nomenclature current in America and with the nomenclature as 

 suggested by Edwards '94-96 is given in the subjoined table. 



