May, 1953 
2A. 
to 
~I 
Legs and abdomen having extremely 
numerous, minute black dots scattered 
OVerSurfaceses ws. ee 23. lutulenta 
Legs and abdomen not having black dots 
scattered over surfaces............ 25 
Penis lobes short, extremely stout, en- 
larged near bases to form a vase-shaped 
structure, fig. 143....24. temporalis 
Penis lobes not vase shaped, figs. 144, 
NE tl OMRON tei omit AT he ie LO 
Caudal filaments white, articulations not 
Hand oregon ir eon 25. coxalis 
Caudal filaments either entirely dark gray 
or brown, or light and with darkened 
PIRALCMN A CONG He fy peo ote oes ane Diy, 
Penis lobes with lateral margins evenly, 
sinuately enlarged toward apexes, and 
maximum width of apical portion as 
great as maximum width of basal por- 
tion, fig. 146.............26. simplex 
Penis lobes with lateral margins not even- 
ly and sinuately enlarged toward 
apexes, and maximum width of apical 
portion less than maximum width of 
basal portion, figs. 142, 147-150. ..28 
Penis lobes with a subangulate, preapical 
enlargement on either side, figs. 142, 
[oo ccmokas 2 eta Se On a 29 
ROTUNDA 
FUNERALIS 
Fig. 145.—Ephemerella rotunda, male geni- 
talia. 
Fis. 146.—Lphemerella simplex, male geni- 
talia. 
Fig. 147.—Ephemerella_ verisimilis, male 
genitalia. 
30. 
Burks: THE MAvyer.ies or ILLINOIS 61 
Penis lobes with a rounded, preapical 
enlargement on either side, fig. 150, or 
lobes with lateral margins parallel 
near apexes, figs. 148, 149.......... 30 
Caudal filaments white, with articulations 
1Red ara ds CRC ater at eee a ee 28. bicolor 
Caudal filaments gray, with articulations 
dark gray or black...29. verisimilis 
Penis lobes with rounded, preapical, 
lateral enlargements, fig. 150...... 
Fe iy te beg PR hans Pay ee 30. minimella 
Penis lobes with lateral margins sub- 
parallel near apexes, figs. 148, 149. 31 
Penis lobes constricted (or narrower) in 
apical third, and inner, apical angles of 
peritreme acute, as in fig. 148; caudal 
filaments yellow-brown near bases, 
color blending into white at apexes, 
and articulations black. .31. funeralis 
Penis lobes constricted in slightly more 
than basal half, and inner, apical angles 
of peritreme blunt, fig. 149; caudal 
filaments light yellow, with articulations 
Ted -Drowlleeee ona elena ACSELVa 
Mature Nympus 
Platelike gills present on abdominal seg- 
ments 3—/, tes, 65.) 166.2 1725 d73se 
VERISIMILIS 
AESTIVA MINIMELLA 
Fig. 148.—Ephemerella funeralis, male geni- 
He 149.—Ephemerella aestiva, male geni- 
tae. 150.—Ephemerella minimella, male 
genitalia. (After McDunnough.) 
