436 
NORTH AMERICAN PLECOPTERA 
Furthermore, we are greatly indebted to Prof. T. D. A. Cock- 
erell, Prof. J. C. Bradley, Mr. P. B. Powell, Prof. C. P. Gillette, 
Prof. C. W. Howard, Mr. H. A. Surface, former State Zoologist 
of Pennsylvania, and Miss Hortense Butler for the collection of 
valuable material. 
Finally, I wish to express my most sincere gratitude to Prof. 
James G. Needham who has supervised my work. As a student 
of the group himself, he is not only most ably fitted to guide the 
work, but his many manuscript notes and sketches of type speci- 
mens have been invaluable in making determinations. To him 
I also wish to extend grateful appreciation for innumerable sug- 
gestions and constant advice and encouragement. One of the 
species, Dictyogenus f phaleratus, which appears for the first time 
in this paper, I am designating new species Needham, since the 
description is a quotation of Prof. Needham’s manuscript. 
Key to the Pteronarcinae and Perlodini 
a. Reticulate venation extending in the fore-wing from costa through the 
anal veins Pteronarcinae 
b. Size large (one and one-half to two and one-half inches); thirteen pairs 
of tracheal gills Pteronarcys 
bb. Size small (about three-fourths inches); seventeen pairs of tracheal 
gills Pteronarcella 
aa. An apical network of cross-veins restricted to the anterior part of the 
wings, never extending in the fore-wing, posterior to the cubital veins. 
Perlodini 
Subfamily PTERONARCINAE 
Adults 
The Pteronarcinae is one of the most distinct groups in the 
order Plecoptera. Although there is remarkable range of size in 
the individuals comprising the subfamily, they can be readily 
distinguished from all others by a reticulate venation reaching in 
the fore-wing from costa through the anal veins. In addition 
they are one of the few groups of the order which retain in the 
adult stage the rudiments of the tracheal gills. But the form of 
the gills, which are tufts of fine filaments, and their position, 
which is on the basal abdominal segments as well as on the 
venter of the thorax, is peculiar to them. 
