September, 1942 
FRISON: 
Fig. 99.—Nymph of Isoperla dicala. 
base to apex, a longitudinal row of long, 
fine setae on dorsal surface of apical seg- 
ments in addition to smaller spinelike ones 
encircling apex of each segment. 
Approximately mature specimens with 
a body length of 10 mm. 
No thoracic, anal or submental gills. 
Nymphal records are as follows. 
MIcHIGAN.—FREE Soi, Great Sable River: 
May 26, 1939, T. H. Frison & H. H. Ross, 
numerous nymphs. Rapip River, Rapid River: 
May 12, 1940, T. H. Frison & H. H. Ross, 4 
nymphs. BaALpwin, Pere Marquette River: 
May 9-10, 1940, T. H. Frison & H. H. Ross, 
8 nymphs. PEAcock, Little Manistee River: 
May 10, 1940, T. H. Frison & H. H. Ross, 
15 nymphs. Irons, Little Manistee River: 
May 28, 1939, T. H. Frison & H. H. Ross, 
many nymphs. Honor, Platte River: May 27, 
m9, I. H. Frison & H. H. Ross, 1 exuvia. 
Brunswick, Brooks Creek: May, 29, 1939,-T. 
H. Frison & H. H. Ross, 1 exuvia. CRAWFORD 
County, near branch of Au Sable River: May 
18, 1936, J. N. Leonard, 1 nymph. 
Minnesora.—E y, 12 miles southeast, Ka- 
Wishiwi River: June 21, 1939 Kon ie Darey, 
1 nymph. 
New Brunswick. — PENogsQuis: 
1939, eer: Frison & 
exuvia., 
Aug. 20, 
alia Brisons jreet 
NortH AMERICAN PLECOPTERA 323 
This species, on the basis of habitus, 
belongs in the Isoperla group or complex 
containing bilineata. ‘Vhe long, deeply 
recessed lobe in the middle of the pos- 
terior margin of the eighth abdominal 
sternite in the male easily separates it from 
bilineata, as does also the lack of a V- 
shaped line connecting ocelli on the head. 
‘The nymph is very dark, with numerous 
conspicuous, short, stout setae; in this re- 
spect reminding one of minuta (Banks), 
but the head pattern is quite different, 
and maxillae have two large teeth at apex 
instead of one. 
Adults were observed at Free Soil, 
Mich., to be emerging during the day- 
time from nymphs clinging to logs on the 
sides of the river bank. This habit of 
emerging during the day has been noted in 
the case of another species, decepta Frison, 
in Illinois. 
Isoperla orata new species 
FEMALE.—General color creamy yel- 
low with fuscous or brown markings. 
General type of coloration similar to that 
of the Isoperla bilineata (Say) complex. 
Dorsum of head, fig. 100, mostly creamy 
yellow; compound eyes and area immedi- 
ately surrounding ocelli black ; lateral ocel- 
li connected with median ocellus by short, 
dark stripes which connect with a large, 
solid, transverse, graduate, dark patch ad- 
jacent to median ocellus. Pronotum most- 
ly creamy yellow except for fuscous or 
brownish area associated with raised ru- 
gosities, fig. 100. Mesonotum and meta- 
notum mostly creamy yellow with some 
fuscous or brownish areas. Abdomen es- 
sentially creamy yellow with slight traces 
of fuscous longitudinal stripe on tergites. 
Antennae, legs and anal cerci practically 
concolorous with body. 
Head wider through compound eyes 
than pronotum; ocelli forming an almost 
equilateral triangle, lateral ocelli some- 
what farther apart than each is distant 
from inner margin of compound eye. 
Pronotum broader than long, approxi- 
mately quadrangular in shape, a distinct 
pattern of raised rugosities on disk each 
side of median pale-colored stripe. 
Legs with first and second tarsal seg- 
ments together much shorter than third, 
first tarsal segment longer than second. 
Wings very pale or hyaline with stigmal 
