well developed, fig. 165; abdominal 
tergites lacking pale spots at bases of 
tubercles. . . 18. subvaria 
Dorsal abdominal tubercles more re- 
duced, fig. 166; abdominal tergites hav- 
ing a pale spot at base of each tubercle 
ee: Ne uly set ys al ROCS 
(BICOLOR Group) 
22. Distance between rows of dorsal abdomi- 
nal spines suddenly increased on seg- 
SENG Dick Oe Re ee: 8 28. bicolor 
Distance between rows of dorsal abdomi- 
nal spines uniformly increasing from 
segments | to7....... 30. minimella 
23. Distance between dorsal abdominal spines 
on segment 5 less than length of that 
segment at median line......... eer 
Distance between dorsal abdominal spines 
on segment 5 equal to or greater than 
length of that segment at median line 
EOE eins SSB Reena ta nt ARTEL Ete in: Ae 25 
24. Rows of dorsal abdominal tubercles 
parallel, fig. 164...... 24. temporalis 
Rows of dorsal abdominal tubercles con- 
verging posteriorly. ..22. prudentalis 
25. Posterolateral spine of abdominal seg- 
ment 3 well developed, its length twice 
as great as width at base........ 26 
Posterolateral spine of abdominal segment 
3 reduced, its length only as great as 
GED DABG at os. "Sac inne side vio apts 28 
26. Posterolateral spine of abdominal segment 
9 slightly incurved; lateral margin of 
segment 9 almost straight........... 
Ys ois pou 5 Oe awe toe ee es, 
Posterolateral spine of abdominal segment 
9 straight; lateral margin of segment 9 
pleatly CONVEX [o> esiotin. foie cats 27 
27. Dorsal abdominal tubercles of segments 
1-3 long and slender, fig. 158......... 
hte b ey figs Sas Conaee 23. lutulenta 
Dorsal abdominal tubercles of segments 
1—3 short and blunt, fig. 159.......... 
NL ie ey ath oii ope 32. aestiva 
29. Paired dorsal tubercles present on occiput, 
thorax, and abdomen. . .33. attenuata 
Dorsal tubercles wanting on occiput, 
thorax, and abdomen 0 
30. Second and third abdominal tergites with 
posterolateral angles produced as spine- 
like projections, fig. 163...... 27. lita 
Second and third abdominal tergites with 
posterolateral angles not produced, fig. 
ic aap Sy Ree ee 26. simplex 
WALKERI Group 
1. Ephemerella lata Morgan 
Ephemerella lata Morgan (1911:112). 
Ephemerella inflata McDunnough (1926:187). 
Mave.—Length of body and of fore wing 
6-7 mm. Body generally very dark brown, 
[ntinois NaturRAL History Survey BULLETIN 
Vol. 26, Art. 1 
almost black, with abdominal tergites slightly 
lighter in color than thorax. Wings hyaline, 
with most veins and crossveins hyaline, veins 
near costal margin of fore wing very light 
yellow. Genitalia with penis lobes fused al- 
most to tips, penial spines lacking; second 
forceps segment short and subangulate, with 
a sharp median constriction, fig. 122; and 
I71A 
Fig. 167.—Ephemerella frisoni, maxilla of 
mature nymph. 
Fig. 168.—E phemerella needhami, maxilla of 
mature nymph. 
Fig. 169.—Ephemerella deficiens, maxilla of 
mature nymph. 
Fig. 170A.—Ephemerella temporalis, gill of 
fourth abdominal segment. 
Fig. 170B—Ephemerella temporalis, gill of 
seventh abdominal segment. 
Fig. 170C.—Ephemerella temporalis, gill of 
fifth abdominal segment. 
Fig. 1714.—Ephemerella needhami, gill of 
third abdominal segment. 
Fig. 171B.—Ephemerella needhami, gill of 
seventh abdominal segment. 
Fig. 171C.—Ephemerella needhami, gill of 
fifth abdominal segment. 
ll tial al 
