Fresh water.

Pl. [18], Fig. 6.

CYMBELLA EHRENBERGII KUETZ.

Valve lanceolate, with ventral margin nearly straight and apices sub-rostrate; median line straight, excentric; axial area narrow; central area widened in the middle; striæ coarsely punctate.

Fresh water.

Pl. [18], Fig. 9.

CYMBELLA AFFINIS KUETZ.

Valve about three times as long as broad, strongly convex on the dorsal side and straight on the ventral; apices sub-rostrate; striæ punctate; axial area narrow, not widened in the middle; median line curved; a small or indistinct punctum on the ventral side of the median line (not shown in the figure).

Common in ponds. Abundant in East Park Reservoir.

Pl. [18], Fig. 18.