1913] Wing Veins of Membracidce 91 



Thus it is the most unreHable cross-vein so far as position is 

 concerned, which is found in the wing. In a few species it 

 does not appear. In Archasia belfragei, media and cubitus 

 dip toward and touch one another at the point where this vein 

 is typically found. In Entylia bactriana, which is an interesting 

 wing in other respects also, media and cubitus anastomose for 

 such a distance as to make this vein unnecessary. The same 

 is true of Publilia concava. In certain forms this vein varies 

 within a species. The figures shown of Thelia bimaculata and 

 Carynota mera show two cross-veins at this point, but this is 

 only occasionally found even in those species. 



The third constant cross-vein is that connecting M3+4 with 

 Cu. It varies in length from a mere attachment, as in Entylia 

 bactriana, to the prominent and important position which it 

 assumes in most of the wings of the family. No membracid 

 wing has been examined in the course of this study which did 

 not show this cross-vein, and as has been suggested in the 

 consideration of cubitus, it has been particularly noted as 

 being an apparent part of that vein. 



Other cross-veins are found, but with no regularity and of 

 no especial significance. R4+5 occasionally does not unite 

 with Mi_|-2 and a cross-vein bridges over (e. g. Platycotis sagittata). 

 M3+4 sometime moves so far from M1+2 that this part of the 

 wing has been strengthened in the same manner and one 

 species at least has added cross-veins to such an extent that the 

 actual condition of the typical form is only conjectural from 

 the material at hand. This species is Phylia ferruginosa, the 

 species possessing the most unusual cross-veining of any Mem- 

 bracid studied. 



The tracheation of the wing-base 



In their basal structure the wings of the Membracidse refuse 

 to agree exactly in structure with those of closely related 

 families, and if the determination of homologies in this study 

 is correct, they more nearly approach the hypothetical type 

 than do any of the other Hemiptera. 



It has been shown in the wing of the Cicada'^- that all the 

 trachese in the wing arise from one main trunk''*-\ In the 

 closely related family of Membracidae it would naturally be 



32. Wings of Insects, pp. 243-249. 



.33. Wings of Insects, p. 244, Fig. 14 and the accompanying discussion. 



