128 ILtinois NATURAL History SurvEY BULLETIN 
legs white or faintly yellow. Abdominal 
tergites uniformly brown, black tracheal 
markings at spiracles, sternites 1-6 deep 
yellow; apical sternites tan; genitalia and 
caudal filaments white; genitalia, fig. 271, 
with fourth forceps segment three times as 
long as wide. 
Known from Illinois, Ontario, Quebec. 
Illinois Record.—Gotconpa: April 30, 
1940, Mohr & Burks, 1¢. 
5. Baetis harti McDunnough 
Baetis harti McDunnough (1924a:7). 
Mave.—Length of body 2.5-3.5 mm., of 
fore wing 3-4 mm. Head very dark brown; 
each antenna brown, shading to yellow at 
apex of flagellum; eyes brown. Thorax dark 
brown, yellow-brown near apex of mesoscu- 
tellum; all coxae brown, legs otherwise light 
yellow to white; wings hyaline, stained with 
brown at base of vein Sc of fore wing; 
stigmatic crossveins of fore wing only three 
or four in number, not anastomosed; hind 
wing, fig. 272, relatively broad at base, costal 
projection well developed, third longitudinal 
vein absent. Abdominal segments 2-6 white 
to yellow, with black spiracular marks; 
apical tergites dark brown, sternites tan; 
genitalia and caudal filaments white. 
Known from Illinois. 
Iliinois Reecords—KANKAKEE: Aug. 16, 
1938, Ross & Burks, 1 6 ; May 17, 1938, H. 
H. Ross, 24 ; July 21, 1935, Ross & Mohr, 
14. Urpana: West Branch Salt Fork 
River, July 11, 1898, C. A. Hart, 82. 
6. Baetis pygmaeus (Hagen) 
Cloe pygmaea Hagen (1861: 54). 
Bactis pygmaeus (Hagen). McDunnough 
(1925a:214; 1925b:172). 
This species was described from a single 
very small female specimen collected in 
eastern Canada along the St. Lawrence 
River. When Eaton examined this type 
(1885:170), it was fragmentary. When Mc- 
Dunnough saw it (19254:172), it was badly 
broken, consisting only of one fore wing and 
part of the mesothorax with the legs at- 
tached. At present, the type is but a bare 
pin, with the label. 
McDunnough (19254:172), however, se- 
cured male and female specimens of a com- 
mon species of Baetis from Ontario and 
Quebec, along the St. Lawrence River, and 
Vol. 26, Art. 1 
was able to match the female of this species 
with the few fragments of Hagen’s type 
which were still preserved at that time. 
McDunnough based his conception, and re- 
description, of this species on these specimens 
and the associated males. I have seen some 
of this topotypic material of pygmaeus, as 
named by McDunnough, and I follow his 
identification of it. 
Ma ce.—Length of body and of fore wing 
3.0-3.5 mm. Head very dark brown to 
black; each antennal scape and pedicel dark 
brown, flagellum lighter smoky brown. 
Thorax very dark brown to black; coxae 
yellow-brown, fore femur faintly stained 
with smoky tan, all legs otherwise white; 
wings hyaline, veins C, Sc, and R, stained 
with tan near bases, stigmatic crossveins 
six to eight in number, uniformly slanting, 
not anastomosed and usually none reaching 
vein Sc; hind wing, fig. 276, relatively nar- 
row, with well-developed costal angulation, 
one or two long, marginal intercalaries pres- 
ent posterior to second longitudinal vein, and 
third vein absent. Abdominal segments 2-6 
white or faintly yellow, black stigmatic 
markings present; apical tergites chestnut 
brown, sternites pale tan to white; geni- 
talia and caudal filaments white. 
Known from the midwestern and north- 
eastern states and southern Canada. 
Illinois Records.—Herop: July 16, 1947, 
sweeping, L. J. Stannard, 1¢. JONESBORO: 
branch of Clear Creek, May 15, 1946, Mohr 
& Burks, 1¢. Quincy: at light, May 18, 
1940, Mohr & Burks, 1 é. . 
7. Baetis frondalis McDunnough 
Baetis frondalis McDunnough (1925:173). 
Mate.—Length of body 4-5 mm., of fore 
wing 5-6 mm. Head very dark brown, 
almost black; each antennal scape and pedi- 
cel yellow-brown, flagellum tan; eyes in life 
red-brown. Thorax almost completely very — 
dark brown to black, mesonotum marked — 
with small, vaguely defined, yellow-brown 
streaks anteriorly on prescutum and later- 
ally on anterior notal wing processes; all — 
coxae brown, front leg faintly shaded with — 
tan, middle and hind legs white to faint 
yellow-brown, fore tarsus slightly shorter 
than fore tibia. Wings hyaline, veins C, Sc, 
and R, faintly stained with brown near 
bases, otherwise all veins hyaline; stigmatic 
crossveins of each fore wing six to eight in 
