May, 1953 
third forceps segment three times as long as 
wide. 
NympuH.—Head and body without dorsal 
spines and tubercles. Frontal shelf of head 
with a pair of small, triangular projections, 
fig. 156. Fore femur enlarged and toothed 
on anterior margin. 
Known from Maine, Michigan, 
York, North Carolina, and Quebec. 
New 
2. Ephemerella tuberculata Morgan 
Ephemerella tuberculata Morgan (1911:112). 
Mate.—Length of body and of fore wing 
8-9 mm. Body generally very dark red- 
brown, with middle abdominal tergites 
usually yellow-brown. Wings hyaline, veins 
slightly grayish or gray-brown. Genitalia 
with penis lobes fused almost to tips, penial 
spines lacking, and inner angles of peritreme 
acute, fig. 118; second forceps segment evenly 
bowed from base to apex, a slight inner en- 
largement near base; third forceps segment 
four times as long as wide. 
NympH.— Head _ with frontal _ shelf 
notched below bases of antennae, and with 
a pair of horns on vertex. Each fore femur 
enlarged and toothed on anterior margin. 
Thorax and abdomen with dorsal, paired 
tubercles. 
Known from Maryland, New York, 
North Carolina, Ontario, Quebec, and Ten- 
nessee. 
3. Ephemerella walkeri Eaton 
Baetis fuscata Walker (1853: 570). 
Name preoccupied. 
Ephemerella walkeri Eaton (1884:129). 
New name. 
Ephemerella bispina Needham (1905: 43). 
Ephemerella fuscata (Walker). McDunnough 
(1931d:214); Traver (1935a: 600). 
Mave.—Length of body and of fore wing 
7-8 mm. Body generally dark brown, with 
abdominal tergites slightly lighter toward 
lateral margins. Wings hyaline, veins 
slightly stained with yellow. Genitalia with 
penis lobes fused almost to tips, spines want- 
ing, and inner angles of peritreme blunt, 
fig. 119; second forceps segment only slightly 
bowed, with an inner enlargement near base; 
third forceps segment four times as long as 
wide. 
NympH.—Head with a broad frontal 
shelf having a notch beneath each antennal 
base, fig. 155; vertex lacking tubercles. Each 
Burks: THE Mayr ties oF ILLINOIS 65 
fore femur enlarged and toothed at anterior 
margin. Prothoracic tubercles small and 
represented by a single pair laterally; dorsal 
abdominal tubercles minute. 
Known from Indiana, New Brunswick, 
Ontario, and Quebec. 
4. Ephemerella cornutella McDunnough 
Ephemerella cornutella McDunnough 
(19315: 82; 1931d: 211). 
Mate.—Length of body and of fore wing 
6-7 mm. Body generally very dark brown, 
abdominal tergites somewhat lighter on 
mesal area. Wings hyaline, veins slightly 
tinged with faint yellow; crossveins almost 
invisible. Genitalia, fig. 121, with penis lobes 
fused almost to tips, penial spines wanting; 
second segment of forceps relatively short 
and straight, an inner enlargement near 
base; third segment four times as long as 
wide. 
NympH.—Frontal shelf of head with a 
pair of strongly incurved, lateral horns, fig. 
157. Fore femur enlarged and bearing teeth 
on anterior margin. Head, thorax, and ab- 
domen without dorsal tubercles or spines. 
Known from Georgia, New Brunswick, 
New Hampshire, New York, North Caro- 
lina, Nova Scotia, Quebec, and West Vir- 
ginia. 
5. Ephemerella cornuta Morgan 
Ephemerella cornuta Morgan (1911:114). 
This species differs from cornutella only 
in that the length of body and of fore wing 
of male are 9-10 mm. each, second forceps 
segment of male genitalia is relatively longer 
and more bowed, fig. 120, and frontal shelf 
of head of nymph bears a pair of horns 
which are relatively less incurved, fig. 154. 
Known from Connecticut, Maine, New 
Hampshire, New York, North Carolina, 
Pennsylvania, Quebec, and Tennessee. 
SERRATA Group 
6. Ephemerella frisoni McDunnough 
Ephemerella frisoni McDunnough (1927a:10). 
Mave.—Length of body and of fore wing 
5.0-6.5 mm. Head dark brown, eyes tan; 
antennal pedicel tan, flagellum brown. 
Thoracic notum dark brown, lateral areas, 
near wing bases, tan; venter dark brown; 
