May, 1953 
June 15, 1938, Ross & Burks, 19. Mc- 
Henry: June 3, 1943, Ross & Sanderson, 
be MouncimE: June 29, 1919, 1¢; May 
25, 1941, Ivabel Johnson, 129. OaKkwoop: 
June 6, 1925, T. H. Frison, 184,192; June 
9, 1926, Frison & Auden, 8192; June 14, 
1935, C. O. Mohr, 12 ; June 5, 1948, Burks 
& Sanderson, 56,12 ; June 23, 1948, B. D. 
Burks, 36. SourH BeEtoir: July 2, 1931, 
Betten, Frison, & Ross, 146, 1°. 
3. Ephemera varia Eaton 
Ephemera decora Hagen (1861:38), 
not Walker. Méisidentification. 
Ephemera varia Eaton (1883:69). 
The types of this species are in the 
Museum of Comparative Zoology. 
The fore wing in the adults has the same 
fundamental color pattern as that in 
simulans, although the dark-colored areas 
are relatively smaller; the hind wing in 
varia, however, lacks the dark spots en- 
tirely. The thorax is relatively lighter 
colored than the thorax of simulans; the 
fore leg of the male is. dark yellow, the 
base and apex of the tibia brown; the 
middle and hind legs are light yellow, almost 
white. The penis lobes, fig. 65, are relatively 
narrower than those in simulans, fig. 63. 
Known from Connecticut, Maine, Michi- 
gan, New Hampshire, New York, Ontario, 
and West Virginia. 
6. PENTAGENIA Walsh 
Pentagenia Walsh (1863:196). 
The adults of Pentagenia are large, 
cream-colored mayflies, each with a con- 
spicuous, dark brown, longitudinal band on 
the dorsum of the thorax. In the males, 
the eyes, which are almost contiguous on 
the meson, are larger than those of any 
other member of the family Ephemeridae. 
Each fore leg in the males is relatively short, 
about one-half as long as the body, and only 
slightly longer than the middle and hind 
legs; the legs in the females are quite similar 
to those in the males. “The wing venation, 
figs. 40, 41, is typical for the subfamily. The 
median caudal filament in both sexes is 
reduced in length. 
In the nymphs, fig. 49, the frontal pro- 
jection of the head has a stout prong at 
each lateral margin, the mandibular tusks 
are short and stout, bearing irregular teeth 
Burks: THe MaAyrtiss or ILLINOIS 37 
along each dorsolateral margin; and the 
apical segment of the labial palp is a broad, 
somewhat scoop-shaped triangle. 
KEYS TO SPECIES 
ADULTS 
Caudal filaments uniformly light yellowish or 
white; abdominal sternites unmarked....... 
Sepia erg ated Ghai ieee ie ee 1. vittigera 
Caudal filaments brown, with narrow, yellow- 
ish band at each articulation; abdominal 
sternites marked with brown lines......... 
Mio be tacts Ca Ate te Meee resend nce he ae le 2. robusta 
1. Pentagenia vittigera (Walsh) 
Palingeitia vittigera Walsh (1862:373). 
Pentagenia quadripunctata Walsh (1863:198). 
Matre.—Length of body and of fore wing 
15-18 mm. Head and body generally cream 
colored, with dorsum of thorax marked 
with brown and entire dorsum of abdomen 
occupied by a conspicuous, dark brown, 
longitudinal band; legs light yellowish, al- 
most white, with variable, vague gray shad- 
ing at articulations; wings hyaline, C, Sc, 
and R of fore wing light yellow, and cross- 
veins in this area yellowish, other veins 
and crossveins hyaline; fore wing often with 
four black dots in a row extending across 
wing from bulla toward posterolateral angle 
of wing; abdominal sternites unmarked; 
genitalia, fig. 62, and caudal filaments very 
light yellow, almost white. 
FEMALE.—Length of body 18-25 mm., of 
fore wing 18-23 mm. Colored as in male; 
apical abdominal sternite with a median, 
V-shaped notch on apical margin, fig. 64. 
Known from Arkansas, Illinois, Iowa, 
Kansas, Minnesota, Missouri, ‘Tennessee, 
and Texas. Although this species in Illinois 
is mever so abundant as the species of 
Hexagenia, the adults of vittigera occur in 
considerable numbers throughout the sum- 
mer along our larger rivers. Apparently, 
vittigera develops only in large rivers. 
Illinois Records.—Specimens, collected 
from June 6 to September 20, are from 
Anna, Bloomington, Cairo, Carbon Cliff, 
Carbondale, Carlyle, Centralia, Champaign, 
Chicago, Dixon, Elizabethtown, Freeport, 
Gibson City, Golconda, Grafton (Illinois 
River), Harrisburg, Havana, Keithsburg, 
McConnell (Rock River), Meredosia (Illi- 
nois River), Mount Carmel, Murphysboro, 
Oquawka, Peoria (Illinois River), Pere 
