1913] Wi7tg Veins of Membracidce 83 



In Ceresa, Micrutalis, Telemona, etc., in which subcosta 

 forms the cephahc margin, the tracheae for costa and subcosta 

 have coalesced. In Heliria, Vanduzea and Enchenopa the 

 trachea has had an influence on the costal margin to form a 

 thickening near the base of the wing. 



Subcosta 

 Subcosta is constant in character throughout the family. 

 It is strong, straight and unbranched and extends the full 

 length of the wing (Fig. 2). It is the anterior vein of the wing, 

 owing to the atrophy of costa, and as such often forms the 

 cephalic margin. In the sub-families Hoplophorida and Mem- 

 bracida^'' the vein is usually contiguous to the anterior margin 

 for its basal half, and then drops down, leaving a terminal 

 membrane anterior to its distal half. Sometimes this membrane 

 occurs down the entire cephalic margin. No splitting occurs 

 at the end of the vein. It sometimes anastomoses with parts 

 of radius as will be shown in the discussion of that vein, but this 

 is due to the peculiarities of radius and to no irregularities on 

 the part of subcosta. Its base occasionally shows a fulln'ess or 

 slack which later straightens out in the vein formation (Fig. 7). 

 Altogether, subcosta is always permanent, straight, clean-cut 

 and independent, both in its tracheation and in its final 

 structure. 



Radius 



The behavior of radius offered one of the most difficult 

 problems of the membracid wing. Instead of the typical five- 

 branched condition (Fig. 8) we have in the venation of this 

 family (Fig. 2) what is seemingly a two-branched condition, 

 with what appears to be a cross-vein connecting the cephalic 

 branch with subcosta. This, in itself, would offer but little 

 difficulty, since if the reduction of the five-branched type were 

 carried far enough by coalescence outward, it would give a 

 two-branched result. The natural method of reduction of 

 radius is by the coalescence of the branches of each half of the 

 radial sector, leaving the sector two-branched and the vein as 

 a whole three-branched. If the same method of reduction be 

 carried further, Ri and the sector only are left, giving a two- 

 branched condition of the whole vein. 



16. See figures of Platycotes, Phylia, Campylenchia and Enchenopa. Nos. 

 51, 52 and 53. 



