May, 1953 
ventral side near apex. Abdominal gills 
borne by segments 1-6 truncate at apexes, 
gills of seventh pair without tracheae; ab- 
dominal tergites usually uniformly brown, 
sometimes tergites with median, lighter spots 
faintly indicated; abdominal sternum white, 
sternite 8 with a median, dark brown spot 
at anterior margin and sternite 9 with a 
median, U-shaped, dark brown mark; caudal 
filaments uniformly tan in basal and middle 
areas, but usually with alternating pairs of 
light and dark segments toward apexes. 
Known from Connecticut, Georgia, Illi- 
nois, New York, Ontario, and Quebec. 
Illinois Records—MomeENceE: May 26, 
1936, H. H. Ross, 16 ; June 15, 1938, Ross 
& Burks, 1¢. Witmrincron: at light, Aug. 
6, 1947, Burks & Sanderson, 52. 
27. Stenonema pulchellum (Walsh) 
Palingenia pulchella Walsh (1862:375). 
The male lectotype of this species, now in 
the Museum of Comparative Zoology, is 
considerably bleached, due probably to ex- 
posure to sunlight sometime in the past, and 
the genitalia are missing. The remaining 
parts of this specimen, however, agree well 
with recently collected material from near 
the type locality. Also in the M.C.Z. is an- 
other male specimen, taken by Walsh at 
Rock Island in 1863 and identified by him as 
of this species. This specimen is in good 
condition and unquestionably agrees with 
specimens at present being identified as of 
this species. Specimens collected very early 
in the season are very large and deep yellow 
in color; specimens taken in midsummer 
are smaller and predominately white. 
Mave.—Length of body 6-9 mm., of fore 
wing 8-11 mm. Face below antennal sockets 
white, vertex yellow, shaded with tan; each 
antennal scape tan, pedicel white, flagellum 
faintly gray in basal part; eyes in life pearl- 
gray. Dorsum of thorax blackish brown, 
meson of mesoscutellum with a white area, 
this area usually extending anteriorly to ends 
of outer parapsides and along lateral scutel- 
lar ridge toward wing bases; metanotum 
with broad, white area on meson; pleuron 
mostly tan, white, or faint pink on semi- 
membranous area anterior to fore wing 
base; mesosternum tan, metasternum white; 
front leg light tan, apexes of tibia and tarsal 
segments dark brown, first tarsal segment 
three-fifths as long as second; middle and 
Burks: CHE Mayr ies oF ILLINOIS 179 
hind legs white; each femur of all legs with 
a median and an apical red-brown band; 
wings hyaline, pale brown stain in stigmatic 
area; fore wing with dark brown shading 
Fig. 361. — Epeorus namatus, terminal ab- 
dominal sternites of female. 
Fig. 362.—Heptagenia diabasia, terminal ab- 
dominal sternites of female. 
hacia 
at base; longitudinal veins of fore wing yel- 
low-brown, crossveins dark brown; veins 
and crossveins in costal area of hind wing 
light yellow, others hyaline. Abdominal seg- 
ments white, a narrow, black or dark red- 
brown crossline at posterior margin of each 
tergite 1-7; dark spiracular dots present; 
terminal three abdominal tergites bright 
orange-brown, sometimes with pink suffu- 
sion also; genitalia, fig. 356, white; caudal 
filaments white, articulations dark red- 
brown. 
NymPH.—Length of body 7-9 mm. Head 
anterior to eyes, and on vertex between eyes, 
dark brown, with numerous pale, freckle- 
like dots, large, pale spot lateral to each com- 
pound eye and, on posterior margin of head, 
at inner eye margins. Pronotum with two or 
three large, pale spots near either lateral 
margin; each tarsal claw with two minute 
denticles; gills borne by abdominal segments 
1-6 truncate at apexes, gills of seventh pair 
without tracheae; abdominal tergites 6, 8, 
and 10 almost entirely dark brown, tergites 
1-5 white, with brown markings, tergite 7 
brown near lateral margins and on meson, 
white elsewhere, and tergite 9 brown with 
large, submedian white areas; abdominal 
sternites 1-8 entirely white, sternite 9 white, 
with longitudinal, brown mark near either 
lateral margin, also sometimes with median, 
brown spot at anterior margin; postero- 
lateral angles of segments 7 and 8 produced 
