154 Annals Entomological Society of America [Vol. VIII, 
1, vein and marginal hairs. The vein hairs are in most cases 
in a single row on nearly all of the longitudinal veins and are apt 
to be equidistant from each other; this is not true for the entire 
course of each vein as the hairs generally come closer and closer 
together in passing from the distal to the proximal part of the 
vein. Besides what one might call the ordinary vein hairs there 
are a number of very much smaller ones which, upon many of 
the veins, alternate with the larger hairs; on account of the 
prominence of the regular vein hairs these smaller ones are not 
at first likely to be seen. The vein hairs are mostly restricted 
to the upper surface and are more numerous and larger on the 
anterior than upon the posterior wings. The longest and thick- 
est vein hairs are found near the base of the anterior wing, these 
are fluted, with many small ridges running lengthwise along the 
hair giving it the appearance of a cog wheel in transverse 
section (Fig. 1). 
The marginal hairs, similar in size and structure to the vein 
hairs, are found not only upon the extreme margin of the wing 
but they extend for a short distance on to both the upper and the 
lower surfaces. In the anterior wing these hairs are longest, 
all lie close down against the margin and are directed toward the 
apex of the wing. Along the anterior margin of the posterior 
wing these hairs are similar in position to those upon the 
anterior wing but along its posterior and outer margins they are 
arranged perpendicular to it; these hairs as well as some upon 
the surface are plumose, the plumules are very small and not 
visible until the hairs are examined with a high power of the 
microscope. 
All vein and marginal hairs are widest at the base and grad- 
ually taper to a point; they are hollow, nearly all are slightly 
curved and each fits into a raised ring-like cuticular opening on 
the surface of the wing. 
2. Large surface hairs. Nearly all of these hairs are 
smaller than those just described, they are also heavier and 
darker and a little more curved. On the anterior wing these 
hairs are more numerous than on the posterior one and in both 
wings they are much more abundant upon the upper surface. 
On the posterior wing most of these hairs are on its outer third, 
except a narrow strip running along near the costal margin, and 
there are several large hairless areas, these are probably due to 
