118 
Psyche 
[December 
CuA is formed like a trough, appearing as a deep groove 
when viewed from above, and as a strong ridge, viewed 
from below. While in Lemmatophora, CuA is still found in 
its primitive position, lying on a weak convex fold of the 
wing, in Sialis this fold has been reversed, so that CuA 
lies at the bottom of a concave fold. CuA in the hind wing 
of all the other Exopterygota I have examined, with the 
possible exception of the Caloneurodea, is either indeter- 
minate or on a more or less convex fold as in Lemmatophora. 
In all the neuropteroids where CuA is well developed in 
the hind wing, it is on a concave fold, as in Sialis. 
Another peculiarity of the Protoperlaria is the struc- 
ture of the stem of MP, which frequently is so weak as to 
be nearly indiscernible. There is little differentiation of 
the wing membrane along the course of this vein, except 
for the occurrence of a row of macrotrichia, and its being 
surrounded by a non-pigmented area. In both wings of 
Sialis , the stem of MP has a similar structure. This con- 
dition is a most unusual one, and its occurrence in Sialis is 
of considerable significance. 
B. Venational Pattern 
The arrangement of veins is fundamentally the same in 
Sialis and in protoperlarians. In Lemmatophora Rs is 
simple, but is 2- or 3- branched in some other members of 
this order. Rs in sialids also is simple, but for a few 
marginal veinlets. Fusion of MA with Rs is of frequent 
occurrence among protoperlaria, but is subject to much 
variation. In Lemmatophora, coalescence of these two veins 
is clear in the posterior wing, as in the hind wing of 
Sialis. In the fore wing of Lemmatophora, coalescence does 
not take place. In Sialis it has, although the connection 
between MA and the base of MP is not clear as in the hind 
wing ; here a weak crossvein may represent the basal piece 
of MA, or the basal piece may have moved toward the 
wing base and disappeared. The basal piece is, however, 
readily identifiable in the fore wings of most primitive 
Raphidiodea and Planipennia. 
Fusion of CuA and MP in the fore wing, characteristic 
of Sialidae and Archisialidae, also occurs in some Proto- 
