Key Position: 18 Back to (17b)
18 a. Test with 1 to 8 large ribs running from middle of the test to the fundus and may extend to form blunt spines or tubercles.

SEE Figure 18-1

 18 b. Test without large ribs.

Proceed to 19

FIGURE 18-1

Difflugia fragosa Hempel 1898
Difflugia fragosa HEMPEL 1898, p. 320, figs. 1-2
Difflugia fragosa Hempel MEDIOLI and SCOTT 1983, p. 22-24, pl. 1, figs. 21-27
Specimen from Lake Erie, Ontario.