1917] Pupal Wings of Nepticula 237 



preserved along the middle of the wing, as is also the cubital 

 trachea (which here lies alongside of media for its whole length), 

 it might be expected that if the second branch of media were 

 M3+4 it would be represented by a remnant of a trachea branch- 

 ing off about as far from the base as the second dichotomous 

 division of radius, and certainly not farther distad than the 

 separation of R4+5 into its branches. No such remnant is 

 discernible and I have therefore interpreted the branches of 

 media in these two genera as Mi and M2 respectively. 



In the genera Scoliaiila and Trifurcula, in the adult wing, 

 three veins which reach the margin below the apex arise from 

 the main vein traversing the middle of the wing, which, as 

 shown by the persistent tracheae within the vein cavity, is 

 formed by the coalescence of the basal stems of the radial 

 sector, media and cubitus in Scoliaula, and by the coalescence 

 of media and cubitus in Trifurcula. The medial trachea so 

 far as it persists is unbranched in both. The first two veins 

 may without doubt, as in the previous case, be regarded as 

 Ml and M2, respectively. As far as any evidence presented by 

 the tracheas is concerned, the third vein may be either M3+4 or 

 cubitus. In most other genera, as noted immediately below, 

 cubitus tends to become obsolete before reaching the margin; 

 if the same course of development has been followed here, the 

 conclusion would be that the third vein is M3+4. 



Cubitus. — In N. platanella the unbranched cubital trachea 

 passes almost straight from base to beyond the middle of the 

 wing, where it becomes obsolete. As before mentioned, in the 

 proximal part of its course, it lies within the same vein cavity as 

 media. In A^. rosaefoliella, the cubital trachea lies alone in a 

 separate vein cavity. A condition similar to that in N. plata- 

 nella is found in Ectoedemia and Obrussa; in Ectoedemia cubitus 

 usually reaches to the margin, in Obrussa it atrophies shortly 

 after its separation from media. In Glaucolepis cubitus has 

 entirely coalesced with media in its proximal portion and with 

 the radio-medial stem beyond. In Scoliaula the cubital 

 trachea lies in the single vein cavity in which are also the medial 

 and radial tracheas, and from which Ri separates near the base. 

 In Trifurcula the cubital trachea, which lies in the same vein 

 cavity as media, branches dichotomously at the same distance 

 from the base as the branching of radius; these branches persist 

 to about the middle of the wing. 



