Key Position: 9 Back to (8b)
9 a. Aperture elliptical without collar.

SEE Figure 9 -1

 9 b. Aperture oval with thin collar.

SEE Figure 9 -2.
FIGURE 9 -1

Heliopera sphagni (Leidy 1874)
Difflugia sphagni LEIDY 1874, p. 157
Heliopera sphagni (Leidy) MEDIOLI and SCOTT 1983, p. 37-38, pl. 6, figs. 15-18
Specimen from Lake Erie, Ontario.

FIGURE 9 -2

Nebella collaris Ehrenberg 1848
Nebella collaris Ehrenberg OGDEN and HEDLEY 1980, p. 94-95
Specimen from Crosswise Lake, near Cobalt, Ontario.