LUCY WRIGHT SMITH 
435 
is restricted to the anterior part of the wing, never extending in 
the fore-wing posterior to the cidiital veins. In the genus .4cro- 
neuria the network is more sub-apical and is confined to the region 
between cubitus, and the posterior branches of the radial sector. 
Figure A. — Diagram of Plecoptera Venation. 
In the venation of the Plecoptera (fig. A) we recognize in both 
wings the following longitudinal veins; C = costa; Sc = sub-costa; 
R = radius composed of Ei = radiusi and Ps = radial sector; ]\I = 
media; Cu = cubitus, composed of Cui = cubitusi, and Cu 2 = cubi- 
tus 2 ; 1st A = first anal vein; 2nd A = second anal vein; 3rd A = 
third anal vein. A few cross-veins recur constantly; they are, 
h = humeral; r = radial; ar = arculus; r-m = radio-medial; m-cu = 
medio-cubital. Two cells of the fore-wing,x = inner inter-radial 
cell, and the anal cell, designated by an asterisk in the diagi-am, 
furnish additional venation characters. 
An extensive examination of material has been made possible 
in this study through the kindness of a number of institutions 
which have loaned us their Plecoptera collections. I wish to 
thank most heartily the Museum of Comparative Zoology, the 
Academy of Natural Sciences of Philadelphia, the United States 
National Museum, the Illinois State Laboratory of Natural 
Sciences, and the State IVIuseum in Albany. 
TRANS. AM. ENT. SOC., XLIII. 
