1913] Wing Veins of MembracidcE 87 



In the distal third of the wing, media branches into M1+2 

 and M3+4, the upper branch usually but not always uniting 

 with R4+5. This is, in most cases, the end of its branching, 

 since the reduction by coalescence outward has obliterated the 

 individual veins Mi, Mo, M3 and M4. In a few cases these 

 veins persist to the point of forming an extra marginal cell. 

 This is true of Archasia helfragei and Ophiderma pubescens, 

 where M3 and M4 are separate, and in Micrutalis dorsalis where 

 Ml and M2 show a very slight space between them. In the 

 latter species this feature, which has been remarked by VanDu- 

 zee in a taxonomic sense-^ is not always constant. In Smilia 

 camelus, M4 has behaved much as has R2 in the same species 

 (see radius) by extending part way into cell M3+4 and probably 

 atrophying toward its base. A peculiar condition is shown in 

 Xantholobus trilineatiis in which Mi and M2 have not coalesced, 

 thus leaving a cell Mi. M3 has coalesced with M2 near the mar- 

 gin of the wing to form the unusual combination M2+3. M4 

 extends part way into cell M34.4 as was seen in the case of 

 Smilia. 



On the whole, media represents a simple, natural reduction 

 and is one of the most constant veins in the membracid wing. 



Cubitus 



With the consideration of cubitus comes a perplexing 

 problem in interpretation. There is no doubt as to the trachea- 

 tion, which is constant throughout the family, but the homolo- 

 gies are not at once evident. From the posterior base of the 

 wing, and separate from the costa-subcosta-radius-media group, 

 come two distinct main stems (Figs. 5 and 15). These must 

 represent cubitus and the anals. The upper stem is typically 

 two-branched which is characteristic of cubitus; the lower is 

 three-branched and seems naturally to be First, Second and 

 Third Anal respectively (Fig. 16). Certain features, however, 

 make this interpretation unacceptable. The first and most 

 important of these is the fact that the point of branching of the 

 anterior trachea occurs so far back in the nymphal wing that it 

 would not appear, and does not appear, in the adult venation. 

 This is entirely inconsistant with the reduction which has taken 

 place in all of the other veins of the same wing, and it is incon- 

 ceivable that while coalescence outward has been taking place 



28. Studies in North American Membracidae, p. 52. 



