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IOWA ACADEMY OF SCIENCE Voi,. XXVII, 1920 
holes (4) and (5) ; rare in Green slough (12) ; a few individuals in 
water from Eittle Sioux river (21). 
Brachionus budapestinensis Daday (Plate VI, Fig. 23). This species 
was found in a tow from a small roadside pond near kettle hole (6) ; 
twelve individuals were found, this being the only rotifer in the tow. 
Brachionus calyciflorus Pallas (Plate VI, Fig. 24). This is a very 
common species, being found in abundance in the canal (2), the sand- 
bar pond (3), kettle holes (4) and (5), a creek near Egralharve (9), 
and the fish ponds (16) ; it was met with more rarely in water from the 
marshes near West Okoboji (10), Gull Point kettle hole (11), Green 
slough (12), Gar lakes (15), Hottes lake (18), and Eittle Sioux river 
( 21 ). 
Brachionus capsuHflorus Pallas (Plate VI, Fig. 25). This species was 
found abundantly in the canal (2), the sand-bar pond (3), marshes near 
West Okoboji (10), and Green slough (12) ; and less frequently in 
kettle holes (4) and (5), Gull Point kettle hole (11), Gar lakes (15), 
and Marble lake (20). 
Brachionus havanaensis Rousselet (Plate VI, Fig. 26). Three varieties 
of this species were found in great numbers in kettle hole (7) ; there 
is great variation as to length of posterior spines. 
Brachionus patulus Muller (Plate VI, Fig. 27). This species was found 
most abundantly in August; it occurred in Lake Okoboji (1), the canal 
(2), creek near Egralharve (9), Gar lakes (15), the fish ponds (16), 
Sunken lake (17), Hottes lake (18), Eittle Spirit lake (19), and Marble 
lake (20). 
Platyias quadricornis (Ehrenberg) (Plate VI, Fig, 28). Found abund- 
antly in Eake Okoboji (1), and kettle hole (5); more rarely in marshes 
near West Okoboji (10) and in Eittle Spirit lake (19). 
Keratella cochlearis (Gosse) (Plate VI, Fig. 29). Collected in great 
numbers from Eake Okoboji (1), the canal (2), the sand-bar pond (3), 
kettle holes (4) and (5), marshes near West Okoboji (10), Gull Point 
kettle hole (11), Gar lakes (15), fish ponds (16), Sunken lake (17), 
Hottes lake (18), Marble lake (20), and Eittle Sioux river (21). The 
variety tecta also was found, in which the posterior spine is lacking; this 
occurred in the canal (2). 
Keratella quadrata (Muller) (Plate VI, Fig. 30). Three specimens were 
found in the canal (2), 
Keratella serrulata (Ehrenberg) (Plate VI, Fig. 31). Found in water 
from a loop in the canal (2). 
Notholca striata (Muller) (Plate VI, Fig. 32). Found in the canal 
(2), along with Keretella cochlearis and K. quadrata. 
Anuraeopsis fissa (Gosse) (Plate VI, Fig. 33). Collected among weeds 
near the mouth of the canal (2), three specimens; kettle hole (5), one 
specimen; Hottes lake (18), one specimen. 
Mytilina mucronata (Muller) (Plate VI, Fig. 34). Two specimens were, 
found with M. ventralis brevispina in water from a weedy canal pond (2). 
Mytilina trigona (GosseE (Plate VI, Fig. 35). Four specimens were 
found with other Mytilinidae in a weedy canal pond (2). 
Mytilina ventralis (Ehrenberg) (Plate VI, Fig. 36). Collected in 
marshes near West Okoboji (10), where it was found quite plentifully; 
