250 The American Naturalist. [March, 
In a study of the scales of the Lepidoptera (the results of 
which have been elsewhere recorded’), a careful examination 
of the wing-membranes of Micropteryx revealed on them, in 
addition to the numerous specialized scales arranged in regu- 
lar rows or tiers over the membrane, a covering of very-fine 
hairs, differing radically from the scales in size, arrangement, 
and mode of attachment to the membrane. These minute 
hairs are present in all the species of Micropteryx I have exam- 
ined, viz.: wunimaculella, mansuetella, clathrata, anderschella, 
chrysolepidella, thunbergella, sparmanella, aruncella, fastuosella, 
seppella, semipurpurella. And further, are present in all species 
of Hepialus yet examined by me, viz.: sylvinus, gracilis, humuli, 
argentata, haydenii, hecta, purpurascens, argenteomaculatus, meg- 
lashani, behrensii and its variety, montanus. 
On the other hand, I have yet to discover these minute 
hairs in any one of the Frenatæ, though I have examined a 
large number of forms distributed widely over the group. I 
am convinced that the presence of this clothing of minute 
hairs on the wing-membranes of the Jugate is a subordinal 
character. 
This clothing may be more specifically described as fol- 
lows: in Micropteryx unimaculella, the foreand hind wings on 
their upper and lower sides are sparsely covered with fine, 
curving, pointed, short hairs, not inserted in sockets or “ in- 
sertion cups,” as are the scales, and not easily rubbed off. 
These hairs average .005 millimeters in length, and are dis- 
tant from each other at their bases a length approximately 
equal to the length of the hairs. The scales of unimaculella 
average from .1 to .15 millimeters in length. 
In Hepialus sylvinus the wings are similarly covered with 
fine hairs, averaging from .02 to .03 millimeters in length. 
The scales of sylvinus are from .2 to .3 millimeters long, or 
about ten times the length of the fine hairs, which I shall 
hereafter refer to as the “ fine hairs” or the “ fixed hairs.” 
? Kellogg, V. L., The Taxonomic Value of the Scales in the Lepidoptera, pp- 
45-89, with 17 figs. and plates IX and X, Kansas University Quarterly, Vol. III, 
No. 1, July, 1894. 
$ This paragraph and two or three succeeding ones referring to wing-clothing 
are mostly quoted from my paper on the lepidopterous scales before referred to. 
