September, 1942 
tergites tend to be connected on hind mar- 
gin of segments by narrow transverse 
line which gives tergites somewhat the 
appearance of having cell-like light spots 
each side of median, longitudinal stripe. 
Cerci long, many segments, progressive- 
ly longer from base to apex, a longitudinal 
row of long, fine setae on dorsal surface of 
apical segments in addition to smaller, 
stout, spinelike ones encircling apex of 
each segment. 
Approximately mature specimens with 
a body length of 8 mm. 
No thoracic, anal or submental gills. 
Nymphal records are as follows. 
TENNESSEE.—GATLINBURG, Le Conte Creek: 
May. 14,1939, T. H. Frison & H. H. Ross, 2 
nymphs, numerous exuviae. West of OZONE: 
Fig. 101.—Nymph of Isoperla orata. 
Frison: NortrH AMERICAN PLECOPTERA 32) 
May 15, 1939, T. H. Frison & H. H. Ross, 
4 exuviae. ELKMONT, Little River: May 14, 
1939, I. H. Frison'& H. H: Ross, 9. exuviae. 
NorTH CAROLINA.—SMOKEMONT, Oconaluftee 
River: May 28, 1934, 10 nymphs. 
This is another species belonging to the 
group or complex of Isoperla species con- 
taining bilineata (Say). The shape of the 
dark area connecting the lateral and medi- 
an ocelli is very suggestive of truncata 
Frison, but the color pattern of the nymph 
and the much broader subgenital plate of 
the adult female indicate it is a distinct 
species. ‘’hat the two species may occur 
in the same territory, at least in northern 
states, is shown by the collection of adult 
females of both truncata and this new spe- 
cies at Hawkinsville, Black River, N. Y., 
ties Lore hOt eels. Feel risone &o bl et. 
Ross). Apparently truncata is most abun- 
dant in the north central states region 
and this new species in mountainous areas 
ot the eastern states. 
Isoperla similis (Hagen) 
Perla similis Hagen (1861, p. 26). Original 
description, @. 
This species was originally described 
from the female and recorded from “Penn- 
sylvania and Maryland.” A single female 
typic specimen from “Pennsylvania— 
Uhler—1858” is in the collection of the 
Museum of Comparative Zoology (Type 
No. 250) and has been compared with 
reared material in the Illinois Natural 
History Survey collection. Needham & 
Claassen (1925) gave additional distribu- 
tional records from New Hampshire and 
New York and described the previously 
unknown male, but did not figure any of 
the important structural features of the 
adults. 
Claassen (1931) gave a brief verbal 
description of the nymph based upon a 
male nymphal skin from which the adult 
was reared. Evidently this nymphal skin 
did not show the distinctive color pattern 
of the nymph, which is somewhat sug- 
gestive of Diploperla hastata (Banks) ; at 
least it was not noted. The pale, longi- 
tudinal stripe down the middle of the 
otherwise brownish abdominal tergites, 
coupled with the color pattern of the head, 
helps to recognize this species, fig. 102. 
The maxillae, mandibles and labium of 
the nymph are as in fig. 103. 
To aid with the future identification 
