1930 ] 
The Mecopteron N otiothauma reedi 
89 
vein. R fuses with M basally, and is contiguous with M 
until it forks — or rather, the space between R and M is 
sclerotized giving the appearance of a union between the 
two veins, although the veins themselves are not as closely 
contiguous as this pigmentation or sclerotization of the 
intervening membrane would suggest (See Fig. 7). R s 
is given off in the basal fifth of the wing, and is richly 
branched, being somewhat like the radial sector of the 
Protoblattid Stenoneura in this respect, though it is of 
course much more like the venation of such primitive fossil 
Mecoptera as “Protomerope,” or the primitive fossil 
Neuropteron Permorapisma (particularly the latter) than 
it is like the Protoblattids, since the Mecoptera and 
Neuroptera are naturally more closely related to Notio- 
thauma than the Protoblattids are. The convex vein Ri is 
apparently unbranched and extends distally below the 
pterostigma pst almost to the margin of the wing, although 
a short backward extension of the pterostigma in this 
region intervenes between the margin of the wing and the 
tip of Ri. The concave radial sector R s is given off in the 
basal fifth of the wing, and is richly branched with 
numerous cellules between the distal portions of its 
branches, and the cellules tend to become elongated and 
more quadrilateral than the cellules of the costal or cubital 
regions. It is quite easy to trace the branching of the radial 
sector, and the branching of its forks into R 2 and R 3 or 
into R 4 and R 5 , in the basal portion of the wing, but the 
tracing of the courses of these branches in the distal por- 
tion of the wing is not as easy a matter as it is in such 
forms as Merope or even Permorapisma, due to the fact 
that the course of these branches is obscured by the tangle 
of cellules in N otiothauma, and on this account the inter- 
pretation of the branches of radius in the figure of the fore 
wing is purely tentative, although in the hind wing of 
Notiothauma the course of these branches can be followed 
with ease. 
M seems to be a concave vein, although it fuses with R 
basally and is contiguous with R in the basal region of the 
wing. The branches of M are also concave veins, so that 
it should be an easy matter to distinguish the course of 
these veins from that of Cui which is a convex vein, but 
