172 Ittinois NatuRAL History SurRvEY BULLETIN 
a narrow, black line extending across face, 
from eye to eye, below antennal bases; eyes 
in life brown, each antenna brown, becom- 
ing hyaline toward tip of flagellum. Tho- 
racic notum dark olive-brown, often with 
a reddish cast toward anterior margin of 
mesonotum, pleuron anterior to wing bases 
light yellow or clay color, elsewhere light 
clay-brown; thoracic sternum chestnut 
brown; wings hyaline, entire stigmatic area 
of fore wing shaded with dark red-brown, 
outer margin of hind wing brown; all veins 
and crossveins brown, fore wing with 3 or 
4 crossveins in each interspace crowded to- 
gether in region of bulla; usually all coxae 
brown, the fore leg dark yellow-brown to 
olive-brown, middle and hind legs light yel- 
low-brown, each femur with a middle and 
an apical, dark-brown color band, apex of 
fore tibia black, first fore tarsal segment 
from one-half to two-thirds as long as second 
segment. Abdomen dark yellow-brown to 
medium brown, with a broad, somewhat 
diffuse, dark brown, transverse band at 
posterior margin of each tergite 2-8 and, 
usually, double, longitudinal, dark brown 
line on meson extending the length of these 
tergites; apical tergites uniformly very dark 
brown; sternum gray-brown, lateral and 
posterior margins of middle sternites usually 
dark brown; genitalia, fig. 345, yellow- 
brown; caudal filaments light gray-tan, ar- 
ticulations brown. 
NympH.—Length of body 12-14 mm. En- 
tire dorsum of head anterior to ocelli and 
vertex between eyes dark brown, freckled 
with pale dots, areas lateral to eyes almost 
completely light. Pronotum variegated with 
fairly large, light spots near lateral margins, 
balance of thoracic notum dark brown; 
pronotum as wide as head; tarsal claws 
without denticles. Abdominal tergites 6 and 
8-10 usually uniformly dark brown, others 
variegated with light spots; gills borne by 
segments 1I-6 truncate at apexes, gills of 
seventh pair without tracheae;_ slender, 
spinelike projections borne by posterolateral 
angles of abdominal segments 3— or 49; 
sternum pale yellow, sternites 3— or 48 
each with a broad, dark brown crossband on 
median two-thirds of anterior margin; ster- 
nite 9 with a broad, longitudinal, dark 
brown band near each lateral margin, these 
two bands sometimes almost or quite joined 
at anterior margin of sternite; caudal fila- 
ments usually uniformly yellow or tan. 
Vol. 26, Art. 1 
Known from District of Columbia, Illi- 
nois, New York, North Carolina, Tennessee, 
and Virginia. 
Illinois Record. — EppyvitLte: Lusk 
Creek, May 16, 1947, B. D. Burks, 1 ¢. 
15. Stenonema vicarium (Walker) 
Baetis vicaria Walker (1853:565). 
Baetis tesselata Walker (1853:566). 
Ecdyonurus rivulicolus McDunnough 
(1933a:40). New synonymy. 
Spieth (1940:336) gives notes made from 
a study of the type of this species in the 
British Museum. The identity of the species 
now is firmly established. McDunnough’s 
rivulicolus differs from vicarium only in 
being slightly smaller and in having the 
tibiae more tan than red-brown; I have 
found those characters to intergrade. 
Matve.—Length of body 10-14 mm., of 
fore wing 12-16 mm. Head brown, vertex 
often tinged with red; eyes in life gray; 
each antenna tan, shaded with brown at 
apex of pedicel and on basal half of fla- 
gellum, dorsum of thorax dark brown, apex 
of scutellum red-brown; pleuron yellow- 
brown, dark red-brown to almost black 
shading present at wing bases and dorsal to 
mid-coxa; thoracic sternum brown, anterior 
and posterior margins of mesobasisternum 
yellow to light brown, wings hyaline, proxi- 
mal part of stigmatic area of fore wing 
shaded with dark red; all veins and cross- 
veins dark brown, crossveins in region of 
bulla in the fore wing usually not greatly 
crowded, usually only two or three in each 
interspace; all coxae brown, with black shad- 
ing on outer side of each, fore femur light 
brown, tibia gray-yellow, with apex black, 
fore tarsus brown, with apexes of segments 
black, first segment from one-fourth to two- 
fifths as long as second segment; middle and 
hind legs yellow-brown, with tarsi darkened; 
each femur with a median and an apical, 
broad, dark red-brown band; some or all 
of the tibiae may be faintly stained with 
red, especially near bases. Abdomen dark 
yellow-brown, heavily shaded with blackish 
brown at posterior margins of tergites 1-7 
and on median longitudinal line; apical three 
tergites lighter, red-brown, with lateral mar- 
gins often salmon-pink; sternites 1-7 yellow- 
brown or red-brown, in lighter specimens 
dark brown shading usually visible near 
posterolateral angles and on meson; geni- 
