142 Ittinoris NaturAL History SurRvEY BULLETIN 
1. Cloeon ingens McDunnough 
Cloen ingens McDunnough (1923 :44). 
Mate.—Length of body 8 mm., of fore 
wing 9 mm. Thoracic notum black, pleura 
light brown, legs gray-brown, and wings 
hyaline. Basal abdominal tergites uniformly 
shaded with gray-brown, with a narrow, 
transverse, black-shaded area at posterior 
margin of each tergite; apical abdominal ter- 
gites chocolate brown; venter dirty white, 
apical sternites faintly stained with brown; 
and genital forceps and caudal filaments 
white, the latter stained with red-brown at 
bases. 
Known from Alberta, Maine, and Que- 
bec. 
2. Cloeon dipterum (Linnaeus) 
Ephemera diptera Linnaeus (1761:377). 
A single female specimen of this Pale- 
arctic species has been taken in Illinois. 
Comparison of this specimen with the de- 
scription given in Eaton (1885:182) and 
with reliably determined European material 
of dipterum leaves no doubt of the correct- 
ness of the identification. C. dipterum is a 
common and widespread European species 
which has not heretofore been proved to be 
present in North America. The description 
given below of the male was written from 
specimens collected in Switzerland, which 
were sent to the Illinois Natural History 
Survey collection by Dr. F. Schmid of Lau- 
sanne. 
Mave.—Length of body 6-7 mm., of 
fore wing 7-8 mm. Thorax very dark 
brown to black, legs tan or brown, wings 
hyaline, with longitudinal veins and most 
crossveins light brown. Basal abdominal 
tergites heavily shaded with dark red-brown, 
basal sternites tan, with dark red-brown 
shading at lateral margins; apical abdominal 
segments dark chocolate brown, almost 
black; genital forceps light yellow, almost 
white; caudal filaments white, articulations 
throughout dark brown to black. 
FEMALE.—Length of body 8 mm., of fore 
wing 9 mm. Head light yellow, almost 
white, without darker markings; bases of 
ocelli and entire compound eyes very dark 
gray, almost black; antennae light yellow, 
each with a narrow band of dark brown 
shading at apex of scape and of pedicel. 
Thorax uniformly light tan, shaded with 
Vol. 26, Art. 1 
brown along posterior margin of mesoter- 
gum; small, brown spot on meso- and meta- 
sternum near base of each coxa; legs light 
yellow, with a small, brown spot on ventral 
side of each middle and hind coxa, at apex 
on dorsal side of each fore trochanter, and 
near apex of each femur; minute, brown 
dot on dorsal side at apex of each of three 
apical tarsal segments. Wings hyaline, with 
light brown shading in costal and subcostal 
interspaces of each fore wing, this shading 
extending from base to apex of wing, but 
interrupted at each crossvein in these inter- 
spaces; 5 crossveins in costal interspace basad 
of bulla, 10 crossveins present in this inter- 
space distad of bulla; crossveins partly anas- 
tomosed in stigmatic area; all longitudinal 
veins brown; crossveins in costal, subcostal, 
first radial, cubital, and anal interspaces 
hyaline, all other crossveins brown; marginal 
intercalary veins brown except in anal re- 
gion. Abdomen light tan, tergites faintly 
shaded with brown; tergites 2-8 each with 
small, longitudinal spot on meson at an- 
terior margin, a pair of rather broad, sub- 
lateral, curved spots on basal two-thirds, a 
pair of very small spiracular dots and a 
pair of narrow, lateral, longitudinal lines; 
tenth tergite with a pair of large, lateral, tri- 
angular marks; abdominal sternum pale 
yellow, with dark red-brown markings; 
sternites 2-8 each with a pair of sublateral, 
longitudinal bars, a minute, transverse line 
at posterior margin at point where each — 
longitudinal, red-brown bar ends, a trans- — 
verse bar at anterior margin extending lat- 
erally from each longitudinal bar to antero- 
lateral angle of sternite, and a short, nar- 
row, longitudinal mark extending posteriorly 
from a point near each anterolateral angle 
of sternite; sternites 2 and 3 also each with — 
a pair of short, longitudinal lines at baso- — 
lateral angles; sternite 9 with a pair of 
vague, fairly large, red-brown spots near — 
anterolateral angles; each paraproct with a 
submedian, longitudinal, brown line. Cau- 
dal filaments white, articulations dark red- 
brown; in basal area of each filament, alter-— 
nating articulations with broader color band. — 
In Europe, Cloeon dipterum has long been 
recorded as ovoviviparous and the length 
of life of an adult female may be as much 
as 3 weeks. The single female specimen — 
from Illinois is probably an adventive. 
Illinois Record—CHAmpalicn: at light, - 
Aug. 26, 1939, C. O. Mohr, 19. 
