The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

As in type, but with the valves tumid in the middle.

May's Landing, N. J.

Pl. [13], Fig. 12.

Fig. 11 is a form found in the blue clay. It differs in the coarser puncta from the var. ventricosa. In outline it resembles Eunotia arcus Wm. Sm., which is Ceratoneis arcus (Ehr.) Kuetz., but the central nodule is not present as in the latter form, which connects Eunotia and Cymbella. It may be a form of E. luna Ehr. (A. S., Atlas, Pl. 286, Figs. 33 and 34.)

EUNOTIA VENERIS KUETZ.

Valve with convex dorsal and straight ventral margins, more or less constricted near the sub-acute apices. Striæ subtle, punctate.

Eunotia incisa Greg.

May's Landing, N. J. Blue clay, Pavonia, N. J.

Pl. [13], Figs. 30 and 31.

Eunotia (proper)