May, 1953 
with a pair of dark, lateral streaks only 
_ 2 Sik Shenae Re 6. frisoni 
(INV ARIA Group) 
14. 
£5: 
Abdominal tergites with a double row of 
erect, conspicuous tubercles.......... 
2 Regge ee ee 11. needhami 
Abdominal tergites either entirely without 
paired dorsal tubercles, or with small to 
minute ones, figs. 165, 166, 173....15 
Legs markedly long and slender, spider- 
TLS ee eer 13. septentrionalis 
Legs not markedly long and slender... 16 
nymph, lateral aspect. 
nymph, lateral aspect. 
Fig. 160.—E phemerella cornuta, fore femur of mature nymph. 
Fig. 161—Ephemerella needhami, fore femur of mature nymph. 
Fig. 162.—Ephemerella simplex, right side of abdomen of mature nymph, dorsal aspect. 
Fig. 163.—Ephemerella lita, right side of abdomen of mature nymph, dorsal aspect. 
Fig. 164.—Ephemerella temporalis, right side of abdomen of mature nymph, dorsal aspect. 
Fig. 165.—Ephemerella subvaria, right side of abdomen of mature nymph, dorsal aspect. 
Fig. 166.—E phemerella rotunda, right side of abdomen of mature nymph, dorsal aspect. 
16. 
a7. 
Paired dorsal tubercles of abdomen en- 
Sinehyalackingwaywh... <ocdto sice «ees 17 
Abdomen with at least rudimentary paired 
Gorsale fubeLCleS. <5... Rac, renee + = 19 
Lateral margin of eighth abdominal tergite 
sinuate, fig. 173; abdominal tergites 5 
and 6 almost completely white....... 
oie ea Sah SS Oe aren Dee 14. argo 
Posterior two-thirds of each lateral mar- 
gin of eighth abdominal tergite straight; 
Burks: THe Mayr ies 
oF ILLINOIS 63 
abdominal tergites 5 and 6 mostly 
browiisss..ci6ae < ointenn doe ries, eet 
Dorsum of mesothorax freckled with pale 
dots in addition to the usual 16 rela- 
tively large, pale spots...17. dorothea 
Dorsum of mesothorax uniform deep 
brown, with relatively large, pale spots 
gites well developed, those of eighth 
segment twice as long as wide at base; 
hind leg with tibia longer than femur 
SCA oe ee 12. aurivillii 
166 
Fig. 158.—Ephemerella lutulenta, dorsal tubercles of basal abdominal segments of mature 
Fig. 159—Ephemerella coxalis, dorsal tubercles of basal abdominal segments of mature 
Lateral spines of apical abdominal ter- 
gites not so well developed, those of 
eighth segment as long as broad at 
base; hind leg with tibia equal to or 
Shorter than femur... 01) sees 20 
Dorsal abdominal tubercles greatly re- 
duced, almost obsolete. ..20. invaria 
Dorsal abdominal tubercles distinct, figs. 
NG 52 GOR ee Eee Re te Sele 21 
Dorsal abdominal tubercles relatively 
