September, 1942 
with paraglossae and glossae extend- 
ing forward about the same distance 
and arranged alongside of one another 
in same horizontal plane (Filipalpia 
OCIS Se ts a 
First tarsal segment short, much shorter 
than third tarsal segment; remnants 
of thoracic or submental gills present 
or absent; forewing with from several 
to many median and cubital cross- 
veins; females without a weakly scle- 
rotized longitudinal band on basal ab- 
dominal tergites contrasting with 
strongly sclerotized lateral margins; 
labium with paraglossae extending 
forward beyond glossae and so dom- 
inating glossae that the latter are much 
reduced (Subulipalpia type)......... 
8. Remnants of branched filamentous gills 
on sides or venter of thorax, in posi- 
tion corresponding to location of 
branched filamentous gills in nymphs 
Capniidae 
......Perlidae 
No remnants of nymphal branched fila- 
mentous gills on sides or venter of 
thorax, or if gill remnants are present 
they are single, not branched, finger- 
like processes (some Perlodidae)..... 
9. Remnant of finger-like gills located near 
each side of outer basal corner of sub- 
SC SIRE rE peel dim: coos ea Perlodidae 
(Perlodes, Isogenus and Hydroperla) 
No remnant of finger-like gills located 
near each side of outer basal corner 
mtrOMeNtUITe. «7-5 ohana Sha ee 
10. Anal lobe of hindwing always present 
and large; anal lobe with 5 to 10 dis- 
tinct veins, exclusive of first anal vein, 
reaching margin of wing; males with 
lobe on posterior margin of seventh or 
eighth, or sometimes both seventh and 
eighth, ventral abdominal segments 
except for. Dictyopterygella.......... 
Anal lobe of hindwing usually present, 
but sometimes small and in Hastaperla 
lacking; anal lobe usually with but 
two to three distinct veins exclusive of 
first anal vein, except Kathroperla 
which may have six or seven, reach- 
ing margin of wing; males without a 
lobe on posterior margin of either sev- 
enth or eighth ventral abdominal seg- 
a Chloroperlidae 
11. Males with lobe on posterior margin of 
seventh abdominal sternite, except in 
Dictyopterygella where all lobes are 
lacking and in Dziploperla luctuosa 
which has lobe on eighth abdominal 
sternite; males with tenth abdominal 
tergite usually distinctly cleft, or if 
not distinctly cleft with subanal lobes 
projecting backward (Dictyopterygel- 
la) or with special terminal dorsal 
abdominal structures (Diploperla luc- 
tuosa, D. duplicata and D. bilobata) ; 
radial sector of forewing with from 
two to five branches, usually with 
three or more; subgenital plate of fe- 
male usually well developed, large 
and frequently covering most of eighth 
abdominal sternite... . 
(Dictyopterygella and Diploperla) 
......Perlodidae 
Frison: NortH AMERICAN PLECOPTERA 239 
Males without a lobe on posterior mar- 
gin of seventh ventral abdominal seg- 
ment but with such a lobe varying in 
size from small to large, always on 
eighth abdominal sternite; males with 
tenth abdominal tergite never distinct- 
ly cleft; radial sector of forewing with 
from two to four branches, but usually 
with two; subgenital plate of female 
sometimes not developed, and when 
present usually not covering most of 
the eighth abdominal sternite........ 
BP oe SRT ae a A NO a Isoperlidae 
NYMPHs 
. Gills present on some of the ventral 
basal abdominal segments........... 
ee a eee ee eee teronarcidae 
Gills absent on all ventral abdominal 
SORITEINS Gemeente ies eek wet. US 2 
. Venter of thorax covered with large, 
overlapping, shieldlike plates........ 
i at ake Oe eo ee ee 8 Peltoperlidae 
Venter of thorax without distinct, large, 
overlapping, shieldlike plates........ 5 
. Labium with paraglossae and glossae 
extending forward about the same 
distance and side by side in the same 
NOVIZON CAP pA yer emg Ree ee eek ce + 
Labium with paraglossae extending for- 
ward much farther than the glossae, 
the latter deeply inset below and be- 
tween the paraglossae so as to appear 
almost as basal segments of them.... 7 
. Second tarsal segment approximately as 
long as or longer than the first seg- 
THCTIC eee ee Te Taeniopterygidae 
Second tarsal segment shorter than the 
FIPStR pee et c A etn A AR Ne se cate 5 
. Small and robust nymphs, hairy; hind- 
wing pads extending considerably out- 
ward from the body at an angle; gills 
present or absent in ventral cervical 
PEP LON wee omits ee Wied) dae Nemouridae 
Small and slender nymphs; hairs few, 
fine or lacking; hindwing pads lying 
about parallel to longitudinal axis of 
body; no branched cervical gills.... 6 
. Lateral margins of abdominal segments 
somewhat rounded, segments widest 
at posterior margin and narrower to- 
ward base; hindwing pads with anal 
lobe or area extending tar beyond 
middle of wing pad; forewing pads 
of males sometimes entirely lacking; 
last abdominal segment in males some- 
times with a conical projection...... 
Wwe eras Beh ie Nie ar Ss Ok Capniidae 
Lateral margins of abdominal segments 
almost straight, abdomen appearing 
more cylindrical; each hindwing pad 
with anal lobe or area small and not 
extending much beyond middle of wing 
pad; forewing pads of males always 
present; last abdominal segment in 
males without a conical projection. . 
Se Cee Lee ne ey tata eee Leuctridae 
. Branched filamentous gills on sides and 
Welter <OretNOLax umes wa. Perlidae 
Without branched filamentous gills on 
Sides or —venter or thoraxa, .. fo 0.5. 8 
. With a small membranous finger-like 
