1948] 
Banks — Perlidee 
119 
6. Last part of prongs about three times as long as broad, 
not scabrous, just before tip with a few distinct 
spicules or short spines ; setae entirely black ; pro- 
meso- and metanotum with an elongate pale spot, 
tips of femora broadly black across modesta. 
Last section of prongs scarcely more than twice as long 
as broad, tip more pointed; no pale marks on thorax 
above 7. 
7. Preapical part of prongs but little longer than apical 
part klapaleki. 
Preapical part of prongs fully twice as long as the api- 
cal part americana. 
Harrisiola flavescens Walsh 
This species, easily recognized by the yellowish base to 
fore wings, is typically from Illinois, but the eastern mar- 
ginipes Provancher is the same species, and occurs from 
southern Canada down to Washington, D. C. The eastern 
forms are sometimes a little darker, but the prongs are 
like those of aWalsh paratype at the M.C.Z. Perla illus- 
tris Bks. and P. innota are synonyms of marginipes. 
Paratype M.C.Z. no. 10127. 
Harrisiola nigrescens sp. nov. 
Head and thorax both above and below largely black, 
with only bosses and a spot on each arm of the V-mark 
pale, under side of head with a few pale spots, hind part 
of metasternum pale, abdomen mostly rufous, last five seg- 
ments with a black apical mark over the posterior part, 
some on dorsum but more on sides and venter, not nearly 
reaching middle of venter ; the sixth and seventh ventral 
segments show a median dark area, not as prominent as in 
flavescens ; setae jet black, palpi black, antennae mostly 
black, but the basal fourth more or less pale ; wings with 
very distinct dark veins, basal costal area before first 
cross-vein black, no sign of the yellowish base of flaves- 
cens; area of anal cell, some in front and beyond also 
black. Legs mostly black, femora with an elongate pale 
streak on outer half before tip, tibiae more brown, but tarsi 
black. 
