234 Annals Entomological Society of America [Vol. X, 



among genera with degraded venation. In some apparent 

 examples of media coalescing with radius, a study of phylogeny 

 within the group will show that the result is due to the atrophy 

 of the base of media and the approximation of the remaining 

 one or two branches of media to the radial sector. 



Within the genus Nepticida we find two types of venation 

 in the fore wing. In one, probably the more primitive, media 

 coalesces with cubitus for a short distance from the base, then 

 passes obliquely to radius just beyond R2+3 and anastomoses 

 with radius to beyond the middle of the wing. In the second 

 type, media coalesces with radius from the base to beyond the 

 middle of the wing. In the first type, the oblique portion of 

 media extending between cubitus and radius appears to be a 

 cross-vein and was formerly so interpreted. The occasional 

 persistence of the trachea within the vein cavity of the imago, 

 and studies on the pupal wings, to be presented below, show 

 that this oblique vein is a part of media. Its presence in the 

 imago indicates the coalescence of media with the base of 

 cubitus. 



The present paper is based upon studies of pupal wings 

 of two species of Nepticida, viz., N. platanella, representing 

 the first type of venation, and N. rosaefoUella, representing 

 the second type of venation. The persistence in the imagoes 

 of some species, of the shriveled tracheae within the vein cavities, 

 has made possible comparisons with other genera. Pupal 

 wings of the more generalized forms, which might have thrown 

 some light upon doubtful homologies as noted in the presenta- 

 tion to follow, were not available for study. In the figures 

 of the wings, the single more or less wavy lines represent 

 tracheae; the even lines enclosing them outline the thickenings 

 which form the future veins. The figures represent the con- 

 dition of tracheae and veins a few days before the emergence 

 of the moth. 



Fore Wings (Figs. 1, 2, and 3). 



Except where otherwise noted, observations on N. platanella 

 are based on the pupal wing illustrated by Figure 1. 



Costa. — In N. platanella (Fig. 2) at a period before the 

 developing vein cavities are clearly defined, the costal trachea 

 is distinct. Later (Fig. 1) it is much shortened and extends 



