88 
Psyche 
[March 
and the humeral veinlet is retained to support the weak- 
ened humeral lobe. In the hind wing of Malacosoma and 
other Lasiocampids there are two veinlets called the 
humeral cross veins by Comstock, 1924 (An Introduction 
to Entomology) but I think it preferable to restrict the 
term humeral veinlet to the first veinlet h of Figs. 1 and 7, 
and to refer to the one distad of it as the posthumeral 
veinlet (i. e., ph. of Fig. 7). These structures are referred 
to as veinlets rather than as cross-veins, since they are 
homologous with the veinlets of the Neuroptera, etc. The 
humeral veinlet h of Figs. 1 and 7, is much stouter than the 
other veinlets; and the weaker posthumeral veinlet ph is 
more pronouncedly curved. 
The veinlets in the broad costal area of the fore wing 
have branched or are connected by cross veins in an 
irregular fashion causing a distortion of the veinlets and 
producing numerous cellules, which are irregularly pen- 
tagonal or hexagonal in the basal region and are more 
elongated and subquadrate in the distal region of the costal 
area. The broad costal area apparently represents a con- 
dition inherited from Protoblattoid ancestors resembling 
Asyncritus in some respects, and the curve in the costal 
margin of the fore wing may also represent the retention 
of a tendency more markedly developed in the Protoblattoid 
insects, instead of these features representing a type of 
specialization peculiar to Notiothauma. 
As is true of Mecoptera in general, the subcostal vein Sc 
of the fore wing (Figs. 1 and 7) is a concave vein, and a 
minus sign (-) has been placed above it in Figs. 1 and 7, to 
indicate this fact. The base of Sc dips below the base of 
the radius R, as is indicated in Fig. 7. After paralleling R 
for some distance, Sc ends at the pterostigma pst of Fig. 1, 
although some of the branches of Sc appear to penetrate 
the pterostigma for a short distance. The wide separation 
of Sc from the costal margin, and its paralleling R for such 
a considerable distance are Protoblattoid features appar- 
ently inherited from a Protoblattoid ancestry. 
The radial vein R is higher than the concave vein Sc, 
and appears to have much the same character as that of 
Ri which is a convex vein, so that R may be regarded as a 
convex vein, although its sector R s seems to be a concave 
