1-58] Adams — Protoperlaria and Endopterygota 125 
F. Conclusions. 
Some evidence for a close relationship between the Pro- 
toperlaria and the Neuroptera has been discussed above. 
This evidence, summarized below, consists in part of dis- 
tinctive wing characters which are shared by the archaic 
Sialidae and the Protoperlaria (a), and in part of some 
similarities between the Plecoptera (derivatives of the 
Protoperlaria) and the Neuroptera (b). To these may be 
added some general characters which would of necessity 
be expressed in any group ancestral to the Endopterygota 
(c). 
a. Distinctive common features of the protoperlarian and 
sialid wing are: 
1. The density and arrangement of veins and cross- 
veins is about the same ; in particular, Rs has usu- 
ally only one or two branches. 
2. There is a strong tendency for coalescence of MA 
and Rs. 
3. The stem of MP is weak. 
4. CuA of the hind wing of Protoperlaria is structur- 
ally similar to that of Sialis, the upper surface being 
deeply grooved. 
5. The distribution of macrotrichia on the membrane 
and veins is about the same. 
b. Features shared by the Plecoptera and Neuroptera, 
indicative of relationship are: 
6. Furcasternum with a coxal articulation. 
7. Generally similar shape and arrangement of ax- 
illary sclerites. 
c. Other features of the Protoperlaria which are not so 
distinctive, but which are consistent with their probable 
role as ancestors of the Endopterygota are: 
8. A well-developed anal fan. 
9. Cerci 
10. Ovipositor. 
11. Tibial spurs, present not only at the apex, but in 
a series along the length of the tibia. 
12. Five-segmented tarsi. 
