Adams — Protoperlaria and Endopterygota 119 
perlaria ( Leucorium , Artinska) , but is not ordinarily found 
among the Planipennia. 
Probably the most striking difference between the wings 
of Lemmatophora and Sialis lies in the shape, there being 
a well-developed anal fan in the protoperlarian, but none 
in Sialis. However, a functional fan is still present in the 
Corydalidae, and a reduced one in the Ithonidae and Poly- 
stoechotidae. Anal fans occur elsewhere in the Endoptery- 
gota, notably in the Trichoptera and Lepidoptera; one 
would therefore expect such a structure to be present in 
the ancestor of the Endopterygota. That its absence in 
Sialis is due to secondary reduction is indicated by the 
still relatively broad base of the hind wing. Reduction of 
the anal fan in Sialis is compatible with a general trend 
in the Neuroptera toward narrowing of the base of the 
hind wing. 
C. Trichiation of the Wings and Veins 
Tillyard (1918) has discussed the trichiation of the 
wings in the Panorpoid Orders ; he distinguishes two types 
of hairlike structures — macrotrichia, with articulated 
bases, equivalent to setae, and microtrichia which are simple 
outgrowths of the cuticle. Macrotrichia are found both 
on the veins and the wing membrane in many Endoptery- 
gota, but among the Exopterygota are largely restricted 
to the veins. Microtrichia occur in both groups, distrib- 
uted uniformly over the surface of the wing, including 
the veins. 
Tillyard (1928a) interpreted the fine hairs covering 
the wing membrane of Protoperlaria as microtrichia; he 
considered the macrotrichia to be restricted to the veins. 
This interpretation now appears to be open to question. 
A careful comparison of these “microtrichia” (Fig. 8) 
with the macrotrichia of Sialis (Fig. 7) discloses that these 
structures possess several features in common: 
a. Their size is approximately the same. 
b. In Lemmatophora, all the setae, whether on the 
veins or on the membrane, appear to have a definite 
basal socket, as do those of Sialis. These are dis- 
tinguishable even in Tillyard’s photograph of the 
wing surface (1928a, Fig. 7). 
