582 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxix. 



in the order named, there will be found a complete series showing- how 

 Cuj has combined with 1st A. It is true that only one branch of 

 cubitus has combined with the anal vein, yet it shows how this coales- 

 cence proceeds. When the medial area of Ei-ar (lig-. 22) is examined 

 it will be noted that M3 and Cu^ have coalesced at apex, crowding the 

 cell M3 back from the margin of the wing just as cell M^ is pushed back 

 in the hymenopterous wing, and it does not need a long stretch of the 

 imagination to understand what would be the result if the vein M3+CU1 

 were to migrate toward the apex of the vein 1st A, as has occurred 

 in the Hymenoptera. The wing of Era,i' shows also how, through 

 the combination of the apices of the veins, the medial cross-vein has 

 been swung around from a transverse to a longitudinal position. This 

 same condition is also shown in the wing of Pantarhes (fig. 21), where 

 the medial cross vein and the first three branches of media assume a 

 position almost identical with that found in the Hymenoptera. It also 

 shows how the branches of R. and Mj have coalesced, the only differ- 



>A^^4.5 



1st A+2d AiSd A+Cu^+2-^M^^^ 



Fk;. 8.— Typical hymenopterous wing. 



ence in the Hymenoptera being that this condition has proceeded much 

 farther and R^ also has combined with Mj. This condition found in 

 Pantarhes is not peculiar to this wing, but is also found in Pipunculus^ 

 Oonops (fig. 27), most Syrphidffi, and many Calyptrate Muscidfe. The 

 wing of Midas (fig. 28) is an interesting example of how far this 

 apical coalescence may proceed. In this wing the coalescence takes 

 place in a different direction, but is just as pertinent to the point in 

 hand. Here veins R.^+.,, R^, and R^, have coalesced with R^ in just 

 the same way that R^ and R- have coalesced with Mj in the Hymenop- 

 tera, the difference being that in the Hymenoptera only two veins 

 coalesce while in this dipterous wing three veins have coalesced and 

 the fourth vein has migrated up to the tip of Rj. Both branches of 

 subcosta are preserved in but ver}" few insects and the peculiar anasto- 

 mosis of Scg and Rj and the formation of the stigma are paralleled in 

 the wings of the Plecoptera. In the genus Nemmira (fig. 29), the 

 anastomosis extends for only a short distance, while in the genus 



