180 Intrnors Naturat History SurRVEY BULLETIN 
as spines, these angles of segment 9 slightly 
produced, spines obsolescent; caudal fila- 
ments brown in basal half, apically alter- 
nating pairs of segments dark and light. 
Known from Illinois, Indiana, lowa, New 
York, Ontario, and Wisconsin. 
Illinois Records.—Adult specimens, col- 
lected April 24 to August 13, are from 
Aroma Park, Aurora, Dixon, Elizabeth- 
town, Erie, Havana, Kankakee, Keithsburg, 
Milan, Momence, Mount Carmel, New 
Boston, Oakwood, Oregon, Prophetstown, 
Rockford, Rock Island, St. Charles, Sa- 
vanna, Shawneetown, Sterling, White Heath, 
Wichert, and Wilmington. 
42. HEPTAGENIA Walsh 
Heptagenia Walsh (1863:197). 
In the males of this important and widely 
distributed genus, the compound eyes are 
large, but are not contiguous on the meson, 
except in the lucidipennis group of species; 
each fore leg is slightly longer than the body, 
the fore tarsus is from one and one-quarter 
to one and one-half times as long as the 
fore tibia, and the first tarsal segment varies 
from one-fifth to nearly one-half as long as 
the second tarsal segment. In both sexes, 
the wing venation is typical for the family, 
fig. 318, with the costal crossveins in the 
basal area usually well developed and the 
stigmatic crossveins not, or sometimes very 
slightly, anastomosed; in the hind wing, vein 
M, diverges from M, slightly basad of the 
center of the wing. In the male genitalia, 
the forceps are four-segmented, the second 
segment being as long as or longer than the 
two apical segments combined; the penis 
lobes, figs. 363-380, are fused on the meson 
two-thirds the distance from the base to the 
apex, each lobe typically bears spines or 
teeth, and a single posterolateral spine often 
is present on each penis lobe. The posterior 
margin of the terminal abdominal sternite 
in the females, fig. 362, is either evenly 
rounded from side to side or has a small 
median indentation. 
In the nymphs, figs. 383-385, the frontal 
margin of the head is entire; the apical seg- 
ment of the maxillary palp is relatively slen- 
der, with the apex acute, bears a dense row 
of hair along the outer margin, and lacks 
pectinate spines; the crown of each galea- 
lacinia of the maxilla bears a row of small, 
Vol. 26, Art. 1 
hooklike teeth; the apical segment of each 
labial palp is extremely broad, with the apex 
truncate; the outer margin bears a dense 
row of hair, below which is a bank of pec- 
tinate spines. In the legs, the femora are 
only moderately flattened, and the posterior 
margin of each bears a dense row of hair 
and a sparse row of short, stout spines; the 
tarsal claws are long, slightly enlarged at 
the bases, and are either edentate or have a 
short row of ventral denticles; there may 
be a prominent ventral tooth in the basal 
area of each claw. Gills are borne by ab- 
dominal segments 1-7, with all gills of the 
same form but not same size. Each gill, fig. 
325, is composed of a dorsal, platelike ele- 
ment and a ventral, filamentous tuft; in 
some species this tuft of filaments is greatly 
reduced or wanting on the gills of segment 
7. None of the gills is extended beneath the 
abdominal venter. The three caudal fila- 
ments are equal in length or the median one 
is slightly the longer. Each of the cerci bears 
fairly prominent setae on the mesal side in 
the basal area; otherwise the cerci are vir- 
tually bare. 
The nymphs of this genus occur under 
stones and among debris in shallow water 
near the banks of brooks, creeks, and rivers. 
They cannot be reared through to maturity 
in stagnant water. 
The species Heptagenia quebecensis (Pro- 
vancher) (1876:267; 1878:127) is shown 
by an examination of the lectotype, now in 
the Provincial Museum in Quebec, to have 
been based on a female specimen of the 
genus Ephemerella. This female specimen 
cannot be identified specifically. 
The species Heptagenia manifesta (Eaton) 
remains unknown. It was originally the 
species identified as Baetis debilis Walker 
by Walsh (1862:371), using specimens 
collected at Rock Island, Illinois. Eaton 
(1871:130) transferred this species to 
the genus Siphlurus without seeing speci- 
mens of Walsh’s material. Later, Eaton 
(1885:253) transferred it to Rhithrogena 
and renamed it manifesta (as he considered 
it to have been originally misidentified as 
Walker’s species). There is no evidence that 
Eaton ever saw Walsh’s material. I have 
been unable to locate specimens determined 
as debilis by Walsh; there is none in the 
Hagen collection at the Museum of Com- 
parative Zoology. 
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