1938 ] 
Neuropteroid Insects 
73 
ORDER PLECOPTERA 
Family Perlidae 
Capniinae 
The genera occurring in the United States can be tabulated 
as follows : 
1. The radius at origin of radial sector plainly bends for- 
ward a little 2 
Radius at origin of radial sector straight 4 
2. Several cross-veins in the subapical area Capnoura 
No such cross-veins 3 
3. First anal vein bends around a large triangular scar 
Capnia 
First anal, although slightly curved, not bent around 
a large scar subgen. Arsapnia 
4. Anal area of hind wing reaches to the tip of wing 
Alio capnia 
Anal area not reaching more than three-fourths of 
way to wing tip 5 
5. No oblique cross-vein beyond end of the subcosta, very 
slender species N emocapnia 
An oblique cross-vein beyond end of the subcosta .... 6 
6. Large, heavy species ; setae very long, usually five or 
six costal cross-veins Isocapnia 
Slender, small species, setae very short, of only a few 
joints, but one or two costal cross-veins . Eucapnopsis 
Isocapnia gen. nov. 
Rather large, heavy species; radius not bent at origin of 
radial sector, an oblique vein beyond end of subcosta, several 
(five or more) costal cross-veins ; setae long, twenty or more 
joints, four or five or more near base very short; anal area 
of hind wing not reaching to tip of wing. Much larger 
species than others of the subfamily. 
Genotype, Arsapnia grandis Bks. 
There are at least four species, Capnia crinita Claassen, 
