336 
head, thorax and abdomen, as illustrated 
in fig. 113. Legs, antennae and anal cercl 
yellowish. 
Head with ocelli forming an almost 
equilateral triangle, median ocellus very 
indistinct; basal segments of mouthparts 
extending out from side of head. Labium, 
mandibles and maxillae as in fig. 112; 
maxilla is particularly distinctive with its 
broad apical end and dense brush of stout 
setae in addition to the long, stout, curved 
outer process and much smaller, adjacent, 
inner spinelike process. 
Pronotum — broader 
markings as in fig. 113. 
Abdominal tergites having general back- 
eround bright yellow with dark longitudi- 
nal stripes, as in fig. 113; some scattered, 
stout, short setae on tergites in addition 
to row on posterior margin of each seg- 
ment. Cerci long, many segmented, seg- 
ments progressively longer from base to 
apex; a longitudinal row of long, fine 
setae on dorsal surface of apical segments 
in addition to smaller spinelike ones en- 
circling apex of each segment. 
Approximately mature specimens with 
body length of 13 mm. 
No thoracic, anal or submental gills. 
than long with 
Nymphal and exuvial records are as fol- 
lows. 
MICcHIGAN.—PEAcockK, Little Manistee River: 
May 10, 1940, T. H. Frison & H. H. Ross, 1 
exivia. North of ST. IGNACE:) May 11,)1940, 
T. H. Frison & H. H. Ross, 3 exuviae. Honor, 
Platte River: May 10, 1940, T. H. Frison & 
H. H. Ross, 3 exuviae; May 27, 1939, ized sl 
Frison & H. H. Ross, 2 exuviae. RAPID RIVER, 
Rapid River: May 12, 1940, T. H. Frison & 
H. H. Ross, 1 nymph. 
Nova Scoria.—Moose River: Aug. 21, 1939, 
T. H. Frison & T. H. Frison, Jr., 1 exuvia. 
TENNESSEE.—GATLINBURG, Le Conte Creek: 
May 14, 1939, T. H. Frison & Howie eRogs, 
1 exuvia. 
The maxillae of the nymph and general 
features of the adult show that this new 
species belongs in that group or subgenus 
of Isoperla (s.l.) which includes marlynia 
Needham & Claassen (= clio of Ameri- 
can authors) ; for clio, Needham & Claas- 
sen (1925) proposed the generic name of 
Clioperla. The nymph in life has a par- 
ticularly strong contrasting pattern of 
dark markings on a bright yellow back- 
eround which, coupled with the peculiar 
construction of the maxilla, makes /ata 
a species that is easily recognized in this 
stage. 
Iutinois NaturRAL History SurvEY BULLETIN 
Vol. 22, Arta 
Isoperla trictura (Hoppe) 
Perla trictura Hoppe (1938, p. 151). Orig- 
inal description, ¢, @. 
This aberrant species was placed in 
Perla when originally described by Hoppe, 
but it probably is best placed in Isoperla . 
(s.J.) and probably eventually will be 
given subgeneric status. Although Hoppe 
has given illustrations of the dorsal termi- 
nal abdominal segments of the male and 
ventral terminal abdominal segments of 
the female, I feel warranted in presenting 
new illustrations of these structures to- 
gether with additional drawings to aid 
future identifications of this species, fig. 
114. At one time, I had planned to de- 
scribe this species as new, but fortunately 
discovered in time the description of 
Hoppe. 
The typic series of Hoppe came from 
Washington. To these typic records I can 
now add the following records, based mostly 
upon material sent to me by Dr. William E. 
Ricker. 
OREGON.—ALSEA RIvER, May 24, 1939, Pil- 
low, 19. LAcOMB: 
Crabtree Creek, June 4, 
3’ TERMINAL ABDOMINAL 
TERGITES 
3 TERMINAL 
ABDOMINAL 
STERNITES 
o& TERMINAL 
ABDOMINAL 
SEGMENTS 
o' HEAD AND 
PRONOTUM 
Fig. 114.—Isoperla trictura. 
? SUBGENITAL 
PLATE 
