134 ILtinois NatrurAL History SuRvEY BULLETIN 
shaded with brown and each fore femur 
stained with tan; wings hyaline, veins color- 
less, stigmatic area of each fore wing with 
numerous partly incomplete and anastomosed 
crossveins; intercalary veins in first inter- 
space long, obsolescent, those in following 
interspaces well developed but shorter; hind 
wing, fig. 277, wide, no marginal inter- 
calaries present, third vein short. Abdominal 
tergites brown, with white area at anter- 
olateral angle and anteromedian area of 
each; a darker brown, median spot at pos- 
terior margin of each tergite; basal sternites 
faint yellow, almost white; apical tergites 
opaque pinkish tan, sternites yellow, apical 
sternite with longitudinal, brown streak near 
each lateral margin; genitalia, fig. 296, and 
bases of caudal filaments tan, filaments white 
distad of bases. 
NympH, MALE.—Length of body 6.0-6.5 
mm. Head and thorax light brown, with 
median, longitudinal, dorsal stripe and apex 
of scutellum white or a faint tan; thoracic 
venter white; legs white, shaded with brown 
on coxae, basal three-fourths of femora, 
apexes of tibiae, and apical one-fourth of 
each tarsus. Abdominal tergites light brown, 
with traces of a median, longitudinal, white 
streak; tergites 5, 9, and 10 mostly white, 
lateral margins of each tergite white; gills 
white, with a single, well-marked, brown 
trachea on each gill of pairs borne by seg- 
ments 2-6, anterior and posterior margins 
of these gills also brown; sternite 1 white, 
all following sternites tan, shading to brown 
at lateral margins, apical three sternites al- 
most entirely brown; caudal filaments tan, 
median one three-fourths as long as each 
cercus. 
Holotype, male.— Havana, Illinois, 
White Oak Creek near Matanzas Lake, 
June 13, 1946, Mohr & Burks. Specimen 
dry, on pin; hind wing and genitalia on 
microscope slides. Specimens of nymphs as- 
sociated with this adult collected on same 
date. 
20. Baetis rusticans McDunnough 
Baetis rusticans McDunnough (1925a: 217). 
Mave.—Length of body 3.5 mm., of fore 
wing 4.0 mm. Head and thorax dark gray- 
brown, with yellow-brown or red-brown 
markings on thoracic notum; legs very light 
yellow-brown, femora shaded with darker 
Vol. 26, Art. 1 
brown; stigmatic crossveins of each fore 
wing only four to six in number and not 
anastomosed; hind wing, fig. 281, with third 
longitudinal vein short and marginal inter- 
calary veins absent. Abdominal tergites 2-6 
gray-brown, apical tergites dark walnut 
brown; genitalia and caudal filaments white. 
Known from New York and Quebec. 
21. Baetis phyllis new species 
This species is similar to brunneicolor in 
having abdominal tergites 1-10 uniformly 
brown in color, the hind wing with three 
longitudinal veins and marginal intercalar- 
ies, and the first segment of the male genital 
forceps tuberculate, the second segment 
frustate. The two differ in that the wing 
veins are brown in phyllis but hyaline in 
brunneicolor; the third vein of the hind wing 
is shorter in phyllis than in brunneicolor, 
and the tubercle of the first forceps segment 
is somewhat better developed in brunnei- 
color than it is in phyllis. 
Mave.—Length of body and of fore wing 
each 6 mm. Head dark brown; each an- 
tennal scape tan, pedicel brown, flagellum 
smoky tan. Thorax brown, with yellow 
along anterolateral margins of mesoscutum, 
along outer parapsides, and on meson at 
posterior margin of mesoscutum; legs white, 
except coxae shaded with brown, each fore © 
femur tan, fore tibia with brown spot at 
apex; wings hyaline, veins of fore wing tan, 
crossveins hyaline, stigmatic crossveins nu- 
merous, anastomosed; hind wing, fig. 282, 
broad, two and one-third times as long as 
broad, costal angulation prominent, veins — 
brown at bases, tan distad, first and second 
veins converging slightly at wing margin, a 
single marginal intercalary between veins 1 
and 2, and two marginal intercalaries be- 
tween veins 2 and 3, a single, irregular cross- — 
vein extending from vein 2 to 3, vein 3 
reaching wing margin slightly basad of the 
middle. All abdominal tergites brown, tenth 
tergite darker brown; narrow, transverse, 
yellow stripe at anterior and posterior mar-_ 
gins of each tergite; dark brown, almost 
black, spiracular lines present; entire ab- 
dominal sternum white, apical sternite 
shaded with brown at lateral margins; first 
forceps segment shaded with brown, bearing 
a minute tubercle at inner apical angle, 
second segment frustate, third segment two 
