Pl. [18], Fig. 8.
CYMBELLA TRIANGULUM (EHR.) CL.
Valve semi-elliptical, with acute ends; median line straight; ventral side half the width of the dorsal, with straight, slightly convex or concave margin; striæ radiate, coarsely punctate.
Glœonema triangulum Ehr.
Baker's Run, Willistown, Pa.
Pl. [18], Fig. 24.
CYMBELLA TURGIDA (GREG.) CL.
Valve semi-elliptical, with acute ends; ventral margin gibbous; ventral side half the width of the dorsal; median line straight; terminal fissures turned downwards; axial area broad; striæ radiate, coarsely punctate.
Baker's Run, Willistown, Pa.
Pl. [18], Fig. 23.