The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

NAVICULA YARRENSIS GRUN.

Valve elliptical-lanceolate, with rounded ends; axial area lanceolate, widened in the middle; striæ, 5 in 10 µ. L. 97 µ.

Cape May, N. J. Common.

Pl. [25], Fig. 14.

Fig. 15, a smaller form, 65 µ in length; striæ, 6 in 10 µ.

Fig. 16, 54 µ in length; striæ, 8 in 10 µ (near var. valida Pant.).

NAVICULA ELEGANS WM. SM.

Valve elliptical-lanceolate, with produced ends; axial area very narrow, central area large, orbicular; striæ strongly divergent in the middle, slightly, if at all, convergent at the ends, curved toward the margin, indistinctly lineate, 9 in 10 µ. L. 95 µ.

Blue clay. Not rare.

Pl. [31], Fig. 1.