ROTATORIA OF THE OKOBOJI REGION 
281 
Rivularia. This species is very uncommon in this region, as more than 
a hundred and fifty growths of Rivularia were examined, and only two 
were found with C. algicola inhabiting them. The two growths which 
did have rotifers in them, were on Ceratophyllum from the canal (2) ; 
one growth had five rotifers in it, the other two. 
Collotheca campanulata (Dobie) (Plate VII, Fig. 28). Found on duck- 
weed roots, together with Vorticella. Two specimens were found, both 
from a stagnant pool near West Okoboji (10). 
ORDER BDBLLOIDA 
Adineta vaga (Davis) (Plate VII, Fig. 29). This species was obtained 
by collecting a handful of dried leaves, twigs, etc., from the eaves of the 
cottage on the laboratory grounds and soaking the material in water for 
twenty-four hours. Along with Adineta vaga were found Rotaria rota- 
toria (see below), and numerous protozoa, notably Paramecium. 
Philodina citrina Ehrenberg (Plate VII, Fig. 30). This species was 
found (rare) in water from Green slough (12), Hottes lake (18), and 
Tittle Spirit lake (19). Its yellowish color is perhaps its most out-> 
standing characteristic. 
Philodina megalotrocha Ehrenberg (Plate VII, Fig. 31). Found only 
in the sand-bar (3). The smallest representative of the genus found here. 
Philodina roseola Ehrenberg (Plate VII, Fig. 32). Found on weeds 
and in tows front the, sand-bar pond (3), kettle hole (4), and Tittle 
Spirit lake (19). This species bears repeated drying and revivifying. 
Rotaria macroceros (Gosse) (Plate VII, Fig. 33). Two specimens were 
found in a marshy, weedy pool near Manhattan (14). 
Rotaria macrura (Ehrenberg) (Plate VII, Fig. 34). Found in the canal 
(2), the sand-bar pond (3), Gull Point kettle hole (11), Green slough 
(12), and Gar lakes (IS). This species is viviparous. One individual 
which was under the microscope for observation had a fully developed 
young rotifer in her coelomic cavity. During the course of the study, 
the body wall of the mother ruptured (probably due to pressure from 
the cover glass caused by drying of the preparation) and the young 
rotifer swam out. It progressed for a short distance through the water, 
swimming by means of its ciliary wreath, and then anchored itself and 
commenced to take food. The mother continued to move her ciliary 
wreath for several minutes, but soon died. 
Rotaria rotatoria (Pallas) (Plate VII, Fig. 35). This species is very 
common. Besides being found in the material from the eaves of the 
cottage (see above, under Adineta vaga), it was found in Take Okoboji 
(1), the canal (2), the sand-bar pond (3), kettle hole (4), kettle hole (5), 
kettle hole (6), kettle hole (7), marshes at West Okoboji (10), Green 
slough (12), Gar lakes. (15), fish ponds (16), Hottes lake (18), Tittle. 
Spirit lake (19), and Marble lake (20). 
Rotaria tardigrada (Ehrenberg) (Plate VII, Fig. 36). Found on 
water weeds and in sediment from the canal (2), kettle hole (4), kettle 
hole (7), swamp at West Okoboji (10). and Tittle Spirit lake (19). 
