The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

Valve large, cymbiform, arcuate on the dorsal, slightly gibbous on the ventral side; axial area linear, broad, slightly widened in the middle; no row of puncta on the ventral side. The puncta form curved longitudinal lines and the innermost row on the ventral side appears sometimes distant from the others, but not as in C. cistula.

Cocconema asperum Ehr.

Cymbella gastroides Kuetz.

Not Cymbella gastroides H. L. Smith, Type No. 118, which is C. mexicana A. S., having a punctum in the middle of the central nodule; in outline it is like C. gastroides var. minor Kuetz.

Blue clay.

Pl. [18], Fig. 1 (an unusual form, but it resembles Grunow's. (Diat. Franz Jos. Land, Pl. 1, Fig. 7.)

CYMBELLA CYMBIFORMIS (KUETZ.) BRÉB.

Valve cymbiform, slightly gibbous on the ventral margin; apices broad, somewhat truncate; a punctum occurs on the ventral side of the median line; striæ, 8 in 10 µ, closely punctate.

Kirkwood Pond, N. J.

Pl. [18], Fig. 2.