May, 1953 
shown by unbroken lines. These stout spines 
borne by the penis lobes occur in three posi- 
tions on the lobes: apical, near or at the 
apex near the meson; lateral, at or near 
the outer lateral margin of each penis lobe 
a short distance from the apex; and basal, 
approximately midway between base and 
apex of the penis lobe; see fig. 10. 
TUBERCULATA 
121 
CORNUTELLA 
SORDIDA 
Fig. 118. — Ephemerella tuberculata, male 
genitalia. 
Fig. 119.—Ephemerella walkeri, male geni- 
talia. 
Fig. 120.—Ephemerella cornuta, male geni- 
talia. 
Fig. 121—E£ phemerella cornutella, male geni- 
talia. 
ely 
WALKERI 
ATTENUATA 
Burks: THE Mayr ties or ILLINOIS 57 
The following keys to the genus Epheme- 
rella do not include the species consimilis 
Walsh, described in 1862, from Rock Island, 
Illinois. No authentic Walsh material of 
this species is known to exist, and the species 
cannot be identified from the description 
alone. Extensive collecting in and around 
Rock Island has failed to turn up any speci- 
SERRATOIDES 
Fig. 123.—Ephemerella frisoni, male geni- 
talia. 
Fig. 124——Ephemerella sordida, male geni- 
talia. 
Fig. 125.—Ephemerella attenuata, male geni- 
talia. 
Fig. 126.—Ephemerella male 
serratoides, 
genitalia. 
Vig. 122—Ephemerella lata, male genitalia. 
