May, 1953 
talia, fig. 344, smoky yellow; caudal fila- 
ments gray-brown or tan, articulations 
brown. 
NymMeH.—Length of body 14-18 mm. 
Head anterior to ocelli brown, freckled with 
pale dots, area lateral to eyes and at pos- 
terior margin of head mostly pale. Pronotum 
with large pale spots at lateral and anterior 
margins, disc with pale dots, rest of thoracic 
notum usually uniform brown; tarsal claws 
without ventral denticles. Gills borne by 
abdominal segments I-6 truncate at apexes, 
gills of seventh pair without tracheae; ab- 
dominal tergites 1-10 with broad, dark 
brown crossband at posterior margin of 
each, these bands sometimes obsolescent or 
wanting entirely on meson of basal three or 
four tergites; brown, mid-dorsal band ex- 
tending from base to apex of abdomen, ter- 
gites 5 and 6 often almost completely shaded 
with brown, occasional specimens with al- 
most entire abdominal dorsum brown; ven- 
ter white, with a broad, dark brown cross- 
band at posterior margin of each sternite, 
entire apical half to two-thirds of terminal 
segment dark brown; posterolateral angles 
of segments 3— or 4-9 produced, spinelike ; 
caudal filaments uniformly tan or yellow- 
brown in basal and middle areas, alternat- 
ing pairs of segments usually dark and 
light in apical areas of filaments. 
Known from Illinois, Indiana, Kentucky, 
Michigan, New Hampshire, New York, 
Ontario, Pennsylvania, Quebec, and Wis- 
consin. 
Illinois Records. — Atto Pass: Union 
Springs, May 15, 1946, Mohr & Burks, 
14. Eppyvitie: Belle Smith Springs, April 
29, 1949, Sanderson & Stannard, 1 ¢. 
16. Stenonema fuscum (Clemens) 
Heptagenia fusca Clemens (1913:254). 
Mate.—Length of body 9-11 mm., of 
fore wing 12-14 mm. Head yellow-brown, 
face with dark red-brown, transverse stripe 
below antennal sockets; eyes gray in living 
insect; each antenna tan, scape and base of 
flagellum shaded with red-brown. Thoracic 
notum dark chestnut brown, apex of scutel- 
lum white or yellow; area of each pleuron 
anterior to base of fore wing and dorsal to 
middle and hind coxae red-brown, pleuron 
otherwise tan or yellow; thoracic sternum 
yellow-brown, with mesobasisternum usually 
entirely yellow; all coxae red-brown, fore 
Burks: THe Mayr ties or ILLINOIS 
173 
leg dark yellow-brown, apex of fore tibia 
and apexes of all tarsal segments dark red- 
brown, first tarsal segment one-third to one- 
half as long as second segment; middle and 
hind legs light yellow-brown; each femur 
with a median and an apical, dark red-brown 
crossband; wings hyaline, entire stigmatic 
area of fore wing washed with yellow- 
brown, crossveins in region of buila often 
not at all crowded, occasionally two or three 
crossveins in each interspace at this point; 
all veins and crossveins of both wings very 
dark yellow-brown. Abdominal segments 
with ground color yellow, tergites usually 
almost entirely shaded with brown, occa- 
sionally this darkening confined to posterior 
margins of tergites and to median dorsal 
line; apical three tergites always tinged 
with bright Mars orange, with white or pale 
yellow on lateral margins; abdominal 
sternum dull yellow, rarely with vague, 
brown shading either side of median line; 
genitalia, fig. 346, grayish yellow; caudal 
filaments pale gray-yellow, articulations 
brown. 
NympH.—Length of body 10-12 mm. 
Head and thorax mostly brown, pale spots 
on lateral margins of head lateral to com- 
pound eyes and near margins of pronotum; 
tarsal claws without ventral denticles. Gills 
borne by abdominal segments 1-6 truncate 
at apexes, gills of seventh pair without 
tracheae; abdominal tergites with rather 
vague, transverse, darkened area at each 
posterior margin, tergites 6 and 7 often al- 
most completely brown; posterolateral 
angles of segments 3— or 4-9 produced, 
spinelike; sternites 1-8 each with a broad, 
transverse, brown crossband at posterior 
margin, sternite 9 with a large, brown spot 
near each posterolateral angle, these spots 
usually extending almost to anterior margin 
of sternite; each caudal filament uniformly 
tan in basal area, alternating pairs of seg- 
ments dark and light in more distal area. 
Known from Michigan, New Brunswick, 
New York, Ohio, Ontario, Pennsylvania, 
Quebec, and Tennessee. 
17. Stenonema ithaca 
(Clemens & Leonard) 
Heptagenia ithaca Clemens & Leonard 
(1924:17). 
Mave.—Length of body 9-10 mm., of 
fore wing 11-12 mm. Head and thoracic 
