476 
NORTH AMERICAN PLECOPTERA 
aa. With tracheal gills. 
b. With five pairs of gills. 
c. A little less than the first half of the costal area beyond the humeral 
cross-vein free from cross-veins; the upper branches of the radial sector 
forked vagans 
cc. Only a small costal area beyond the humeral cross-vein free from cross- 
veins; the upper branches of the radial sector not distinctly forked, but 
merged with the network of cross-veins aurea 
bb. With two pairs of gills. 
c. Female vulvar lamina trapezoidal, with a shallow, U-shaped, apical 
notch 9 lineata 
cc. Female vulvar lamina truncate, scarcely produced beyond the border 
of the eighth segment but cut off from it by oblique comers. 9 americana 
Arcynopteryx lineata new species 
Adult 
Distribution . — Old Forge, New York. 
9 . — Length to tip of wings, 22 mm.; expanse of wings, 34 mm.; length of 
antennae, 9 mm.; length of setae, 11 mm. 
Color dark brovTi varied with yellow, pubescent. Head with three small 
ocelli arranged in an isosceles triangle, the lateral ocelli equidistant from each 
other and the inner margin of the eyes, the distance between them a third 
greater than the side of the triangle. On either side of the ocellar triangle, a 
little closer to the lateral ocellus than to the inner margin of the eyes, is a rather 
flat, elliptical tubercle. M-shaped mark fairly prominent. Head, yellowish- 
brown, a blackish-brown, rectangular, frontal spot with short horns extending 
posteriorly to .the paired ocelli; entire occipital border yellow with a broad, 
median, triangular extension passing forward with its apex in the apex of the 
ocellar triangle; anterior to the yellow border, a dark brown coarsely sculp- 
tured oval area on the lateral occipital regions. Lender side of head yellow’ish, 
palpi and antennae brown. 
Prothorax quadrangular, wider than the occiput, breadth almost twice as 
great as the width, front and hind margins a little convex, sides straight, angles 
rounded ; a broad, median, yellow stripe, inner lateral fields with glossy corru- 
gations. Meso- and metanotum dark brown. Venter of thorax pale with a 
large, brown, median, shield-shaped spot on each of the three segments, on 
the anterior border of the last two segments, transverse bands running out 
from the median spots. Legs dark brown with femora and upper part of tibiae 
a little paler in coloration. Wings with yellow-brown venation, an irregular 
network of cross-veins between costa and the branches of the radial sector; 
nearly the first half of the costal area beyond the humeral cross-vein free from 
cross-veins; the length of the inner inter-radial cell three times as great as its 
base. A single pair of small, white, fleshy, finger-like gills on the lateral margins 
of the submentum. 
