30 
KEY TO THE GENERA OF AISCHNID OF THE UNITED STATES. 
Imagos. 
AA. Upper part of arculus equal to or longer than its lower 
part, its upper sector arising near the lower sector and 
far distant from the median vein above; anal loop evi- 
dently 5-7-sided. 
aa. Supplementary sector, just back of the usually forked 
radial (subnodal) sector, nearly straight and sub- 
parallel to it, separated from it by one or two (rarely 
three) rows of cells. 
bb. Radial sector forked near the middle of its length; 
first anal vein leaving the border of the anal loop 
at its first angulation, border continued by a cross- 
vein which usually meets an apparent fork of the 
second anal ; bottom of the loop accordingly 3-sided, 
the part formed by the first anal short, not longer 
than the remaining distance to the stem of the 
second anal. 
ce. Anal loop sub-oval, much as in Macromia, wide but 
not deep, with a row of, usually, three cells bor- 
dering the anal vein, and a second irregular row 
along the bottom of the loop; triangles 3-celled 
(rarely 4-celled), inner side not receiving a cross- 
vein; supratriangular spaces with 2 or 3. cross- 
veins. I. Nasieschna. 
c. Anal loop deep, transversely oblong, with two (rarely 
three) vertical rows of cells, ending in two or 
three cells on the anal vein ; anterior wings with 
discoidal triangles 5—7-celled, the inner side 
receiving a cross-vein, and the supratriangular 
space with 4 or 5 cross-veins.: Il. Kpieschna. 
b. Radial sector not forked; bottom of anal loop normally 
2-sided, one of these sides much longer than the 
other, formed by the base of the first anal, the other 
