108 Annals Entomological Society of America [Vol. VI^ 



only the first group but he believes that the nodal cross vein in 

 the juciindus group is the untracheated cross vein between Ri 

 and R3 (Fig. 44). In this case the nodal cross vein in Sca- 

 phoideiis would be Ri when the "nodal vein arises from discal 

 cell" and R2 when the "nodal vein arises from anteapical cell". 

 In most of the genera of the Jassidce radius branches once 

 and only once, the resulting branches being R2+3 and R4+5 

 (Figs. 1, 5, 6, 20, 22, 26, 28, 62), In several cases referred 

 to above R2 separates from R,3. In only one genus examined, 

 Eutettix (Fig. 46) has R4 and R5 been found separated. In this 

 case R4 occurs as a cross vein between R2+3 and R5. R2+.S is 

 much atrophied and R4 extends to the margin traversing the 

 region usually occupied by R2+3. In a single genus examined, 

 Empoasca (Fig. 66), radius extends as a single unbranched 

 trachea from the base of the wing pad to the apex. Although 

 in the adult wing, in many cases, there is a cross vein con- 

 necting radius with the margin of the wing. 



MEDIUS OF THE FORE WING. 



Medius in the Jassidce is typically two-branched. These 

 branches embrace Mi and M2, and M3 and M4 respectively. 

 Mi+2 is well developed in Chlorotettix (Fig. 43) where it runs 

 parallel to R4+5. It is not so well developed in Parabolocratus- 

 (Fig. 23) Platy?netopius (Fig. 26) and Gypona (Fig. 8). In 

 Deltocephalus (Fig. 28) M1+2 is reduced to a mere spur. In the 

 other genera studied medius consists of a single unbranched 

 trachea which extends from the base to the apex of the wing pad,, 

 although in most cases there is a strong transverse vein connect- 

 ing medius with R4+5. The writer believes that the above 

 series, as outlined, represents fairly well the development of 

 medius from a two-branched condition to a single unbranched 

 trachea. If this conception be correct M1+2 must have come to 

 lie parallel with R4+5 and has been gradually reduced until the 

 present time it is at most merely a cross vein connecting medius 

 with R4+5. The vein having persisted in some cases notwith- 

 standing the fact that the trachea has been lost. This is 

 especially evident in Agallia (Fig. 1), Scaphoideus (Fig. 44) 

 and Eutettix (Fig. 46). 



In the Typhlocybida (Fig. 64 and 66) medius is very evidently 

 two branched. In Typhlocyba (Fig. 64) R4+5 is greatly reduced 



