LUCY WRIGHT SMITH 
459 
Nymphs 
a. With thick frinpjes on the femora and tibiae, and the filaments of the gills 
rather stout, erect • “a” 
aa. Without thick fringes on the femora and tibiae, and the filaments of 
the gills, thread-like, long, slender torosa 
Pteronarcella regularis Ilagen 
Adult 
1873. Pleronarcijs regularis Ilagen, Bull. Geol. Surv. of Col., p. 573. 
1900. Pteronarcella regularis Banks, Trans. Amer. Ent. Soc., 26: 242. 
Distribution . — Sierra Nevada; Selkirk Mountains, British 
Columbia; Wyoming; Colorado. 
cf. — Long-winged, — length to tip of wings, 15 to 17 mm.; expanse of wings, 
28 mm. Short -winged, — length to tip of abdomen, 12 mm.; expanse of wings, 
18 mm. 
9 . — Length to tip of wings, 19 mm.; length of antennae, 11 mm.; length of 
setae, 8 mm.; expanse of wings, 35 mm. 
Dark brown, paler beneath. Head as broad as prothorax; lateral anterior 
margins carinated; a blackish spot through the ocelli, at the level of the ante- 
rior ocellus a lateral extension reaching the carinae, which are also blackish, a 
little before the posterior ocelli another lateral extension, in most cases less 
conspicuous than the anterior one and in some specimens entirely lacking; on 
either side between the lateral bands a prominent, pale yellow tubercle; usually 
a dark brown patch on either side on the occipital margin. The ventral aspect 
of the basal segments of the antennae often yellow. 
Prothorax nearly square, the width a little greater than the length, sides 
straight, front and hind margins very slightly convex, angles rounded, a more 
or less conspicuous, median, yellow line, embossed markings on the disc. 
Tarsi pale beneath, very dark brown above, especially the second and third 
segments. Wings hyaline, veins strong, dark brown. Both long and short 
winged males in this species. 
Abdomen cylindric, paler beneath, and in some specimens a tendency for a 
paler dorsum, sides dark. 
Male. The dorso-lateral posterior margins of segments three to nine with 
rounded, hairy knobs — those on the third and fourth segments more or less 
small and inconspicuous, the others prominent. Segment nine greatly pro- 
duced, the posterior border truncate, on the dorsum between the two lateral 
knobs a broad scoop-like prolongation pointing anteriorly. On the venter the 
middle area of segment nine, cut off by lateral carinae, the po.sterior border 
produced and evenly rounded. The tenth segment and the supra-anal plate 
completel}^ hidden by the ninth segment. The sub-anal j)lates dark brown, 
with dorsal appendage-like processes curved anteriorly, their tips reaching the 
base of the “scoop” (fig. 28). 
Female. The vulvar lamina almost as broad as the segment at the l)ase, 
sides gradually sloping to a narrow rounded tip, produced beyond the posterior 
TRANS. .\M. ENT. SOC., XLIII. 
