314 
equilateral triangle, distance between ocel- 
li about the same as each lateral ocellus 
‘s removed from compound eye. 
Pronotum approximately quadrangular, 
broader than long, a distinct pattern of 
raised rugosities on surtace each side of 
pale, median, longitudinal stripe, with pos- 
terior end of stripe broader than anterior 
end, fig. 87. 
Legs with first and second tarsal seg- 
ments together shorter than third, first 
tarsal segment longer than second. 
Wings hyaline with costal margins pale 
yellowish, venation light brown. 
Abdomen. fig.. 87, with, tenth tergite 
not cleft but with a distinct, depressed, 
median, longitudinal trough almost free 
of stout setae and separating flanking 
patches of numerous short, stout setae; 
subanal lobes recurved upwards over tenth 
tergite and with prominent, slender, long, 
sharply pointed tips; aedeagus membran- 
ous with distinctive shape, fig. 87; ninth 
sternite produced much beyond tip of 
abdomen and rounded behind ; eighth ster- 
nite with a prominent median lobe on 
posterior margin, fig. 87. 
Length to tip of wings 10 mm.; length 
to tip of abdomen 9 mm. 
FEMALE.—Head, thorax, basal abdom- 
inal segments and appendages in general 
similar to those of male but slightly larger 
‘n size. Important differences are as fol- 
lows: eighth abdominal sternite, fig. 87, 
with subgenital plate partly produced over 
ninth sternite and deeply notched in most 
specimens but occasionally only slightly 
indented. 
Holotype, male.—Spearfish, Spearfish River, 
Se De july 27701940, 1. Frison & T. H. 
Frison, Jr. 
Allotype, female——Same data as for holo- 
type. 
Paratypes. — SouTH DAKOTA. — SPEARFISH : 
Same data as for holotype, 456, 202. 
British COLUMBIA.—VANCOUVER: 
1936, H. H: Ross, 12. 
CALIFORNIA.—Mono COUNTY, Convict Creek: 
July 3, 1938, H. J. Rayner, pEeh 
CoLoRADO.—HARTZEL: July 22, 1938, H. H. 
& J. A. Ross, 19. IOLA: June 22, 1934, ele- 
vation 7,450 feet, H. Pratt, 2&. ECKERT, 
Surface Creek: June 28, 1938, Lanham & 
Bauer, 29. GRANBY, Colorado River: July 
24091938 tl emia) A. Ross, 3¢. LAKE 
GeorGE, South Platte River: July 422, 19338, 
H. H. & J. A. Ross, 1:O% 
IpaHo.—ST. ANTHONY: June 28, 1938, H::S. 
Leliord elas 
MoNTANA.—HARrRISON: July 8, 1936, H. in 
Ross, 12. Toston, Missouri River: June 22, 
Julya2e, 
I_LINnots NATURAL History SURVEY BULLETIN 
Vol. 22500 gee 
1940, H. H. & J. A. Ross, 15.4, 159°) Noxon: 
Clark Fork River: June 23, 1940, Bate 
J. A. Ross, 1¢. 
OREGON. — FRENCHGLEN, Harney County, 
Blitzen River: July. 11, 19355que™ Jewett, 
Jr., 16. Five miles south of UNION CREEK on 
Mill Creek: June 24, 1937, S. G. Jewett, Jr., 
1a@. Forr KiaMaTH: June 26, 1937; 752ies 
Jewett, Jr., 34, 19. WILLAMETTE River: May 
26, 1938, C. Jensen, 14, 19. Near mouth of 
WILLIAMSON River, July 8, 1938, R. Dimick, 
on 
Uran.—Ocpen Canyon: June 21, 1937, O. 
E. Hardy, 19 ; June 23, 1938, Hardy & Stains, 
1¢. BLAcKSMITH ForK Canyon: June 20, 
1937, Harmston & Smith, 8¢,°69. HunTs- 
VILLE; June 23, 1938, Hardy & Stains, 19; 
June-27,91937,-G.0 Knowlton, 19. SUNSET: 
July 26,1 933,,Ga8. Knowlton, 19. PARADISE: 
June 14, 1938, Hardy & Stains, 144, 129; 
KanosH Canyon: May 27, 1939, Knowlton 
& Harmston, 1¢, 32. EDEN: July 15; 19s8; 
G. F. Knowlton, 19. Uinta: June 18,, 19375 
G. F. Knowlton, 2¢, 29. LOGAN CANYON: 
July 11, 1938, DoE & ASOT. Hardyie 
SMITHFIELD: May 13, 1939, Knowlton & Harm- 
StOliprooee 
Wyominc. — Boutper, ‘Tributary of Pine 
Branch: July 6, 1936, H. H. Ross, 36, 29. 
PINEDALE, Green River: July 6, 1936, H. H. 
Ross, 19. CENTENNIAL: July 2, 1933; eae 
& J. No Knullair. 
Nympu.—General color pale yellow- 
‘sh with darker areas on head, thorax and 
abdomen, as in figs. 88 and 89; speci- 
mens exhibit color variation from a light, 
fig. 88, to dark, fig. 89, phase; nymphal 
male in life sometimes shows reddish ab- 
dominal coloring as in adult. Antennae, 
legs and anal cerci mostly yellowish. 
Head with three ocelli forming an al- 
most equilateral triangle, lateral ocelli 
about as far apart as each is distant from 
inner edge of compound eye; no occipital 
ridge; basal segments of mouthparts not 
extending out from side of head. Labium, 
maxillae and mandibles as in fig. 87. 
Pronotum broader than long, 
markings as in figs. 88 and 89. 
Abdominal tergites with general back- 
ground yellowish and with dark longi- 
tudinal stripes as in figs. 88 and 89; some 
scattered, stout, short setae on abdominal 
tergites in addition to row on posterior 
margin of each tergite. Cerci long, many 
segmented, segments 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 encircling apex of each segment. 
Approximately mature specimens with 
body lengths, exclusive of appendages, in 
males 11 mm. and in females 12 mm. 
with 
