130 ILtinois NaturAL History SurvVEY BULLETIN 
Allotype, female—Same locality as for 
holotype, June 9, 1948, Burks & Stannard. 
Specimen in alcohol. 
Paratypes.—Oakwood, Illinois, June 4, 
1948, B. D. Burks, 14 adult, 34 subi- 
magoes. Specimens in alcohol. 
9. Baetis herodes new species 
This species agrees with parvus Dodds, 
described from Colorado, in having the 
second vein of the hind wing forked, and 
the first segment of the male genital forceps 
nontuberculate. The two differ in that the 
abdominal tergites 2-6 are uniformly white 
in parvus, but are shaded with red-brown 
at the posterior margins in herodes; in par- 
vus, the hind wing has a single marginal in- 
tercalary vein between the branches of the 
second vein, while, in herodes, the hind wing 
has one long and two short marginal inter- 
calaries between the branches of the second 
vein. McDunnough (1925a:214-5; 1925): 
172) recorded, as the Colorado species par- 
vus Dodds, a Quebec species having the 
venation of the hind wing similar to that of 
herodes. He had female specimens only. 
As many of the southeastern Canadian spe- 
cies of mayflies also occur in southern Illi- 
nois, these Quebec female specimens actu- 
ally might be the females of herodes. Un- 
fortunately, female specimens of herodes 
have not yet been secured here in Illinois. 
Mate.—Length of body and of fore wing 
5.0-5.5 mm. Head very dark brown, almost 
black; scape and pedicel of each antenna dark 
brown, flagellum smoky yellow; each eye in 
life with upper facets dark brown, lower 
ones black. Thorax black, becoming dark 
brown after death; wings hyaline, stigmatic 
crossveins partly anastomosed, 9 to 10 in 
number; hind wing, fig. 275, with prominent 
costal projection, second vein branched, two 
strong and one vestigial marginal intercalar- 
ies present between branches, third vein 
reaching posterior margin of wing at a point 
three-fifths the distance from base to apex 
of wing; numerous vestigial crossveins pres- 
ent; fore leg smoky, fore tibia shaded with 
brown at apex, middle and hind legs faintly 
yellow, almost white, apexes of femora and 
bases of tibiae stained with brown. First 
abdominal segment brown; tergites 2-6 
white, with a transverse, brown-shaded area 
at posterior margin of each tergite, small, 
black blotch at each spiracle; tergites 7-10 
Vol. 26, Art. 1 
dark red-brown; sternites 2-6 white, 7-10 — 
lightly shaded with red-brown, and 10 also | 
shaded with dark gray-brown at lateral mar- 
gins; caudal filaments white. Genitalia: first 
forceps segment nontuberculate, smoky 
brown, following segments faintly yellow; 
second and third segments equal in length, 
second segment frustate, third segment 
slender, bowed, and slightly enlarged to- 
ward apex; fourth segment globose, one and 
one-half times as long as wide. 
FEMALE.—Unknown. 
NymPH, MALE.—Length of body 6-7 mm. 
Head and thorax mottled brown and white, 
legs white, with gray-brown shading on 
coxae, at base, middle, and apex of each 
femur, and in middle of each tibia and tarsus. 
Abdominal tergites 1-4 and 6-7 mostly 
brown, tergites 5 and 8-10 mostly white; 
abdominal sternites white, with longitudinal, 
brown streak near each lateral margin of 
sternites; each gill having a black, median 
trachea with a few short, lateral branches; 
each gill of seventh pair slender and pointed — 
at apex; median caudal filament almost as © 
long as cerci, caudal filaments light tan, — 
with a brown crossband near tip of each. 
A female nymph associated with these — 
male nymphs, and apparently of the same — 
species, has abdominal tergites 1-9 uni- 
formly brown, tergite 10 white, and each 
caudal filament uniformly tan, without a — 
brown crossband. 
Holotype, male.—Herod, Illinois, Gib- — 
bons Creek, April 9, 1947, B. D. Burks. — 
Specimen dry, on a pin. 
Paratypes.—ILLINoIs.—Same data as for 
holotype, 14 ; April 10, 1947, 18 subimago. 
Nymphs and exuviae also were collected at 
Herod, Illinois, April 4-10, 1947. 
INDIANA. — SPENCER: McCormick’s — 
Creek, April 27, 1948, W. E. Ricker, 36. 
Of these paratypes, one adult male is dry, 
on a pin; three adult males and subimago 
male are in alcohol. 
10. Baetis cleptis new species 
This species is similar to erebus Traver, 
described from Arizona, in that the hind 
wing is long and narrow, and has a prom- — 
inent, hooklike costal projection, the median 
abdominal segments are dark brown, and _ 
the first male genital forceps segment has a 
fairly large, rounded anteromedian projec- 
tion. B. cleptis differs from erebus in that 
