The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

STAURONEIS PHŒNICENTERON EHR.

Valve lanceolate, obtuse; striæ radiate, 18 in 10 µ, distinctly punctate. L. usually 125 µ but sometimes 200 µ.

Common in fresh water.

Pl. [27], Fig. 1.

STAURONEIS ANCEPS EHR.

Valve lanceolate, with rostrate or capitate ends; stauros in some cases does not reach the margin. The varieties are very numerous.

Var. gracilis (Ehr.) Cl.—Valve lanceolate, striæ very fine; margin of stauros striated. L. 100 µ. Cape May, N. J. Pl. [27], Fig. 5.

Var. amphicephala (Kuetz.) Cl.—Valve capitate at the ends; striæ, 24 in 10 µ. L. 47 µ. Fresh water. Pl. [27], Fig. 7.

Var. ?—Valve with produced ends; striæ, 30 or more in 10 µ. L. 104 µ. Willistown, Pa. Pl. [27], Fig. 4.

Var. ?—Valve with produced ends; striæ, about 28 in 10 µ, punctate. L. 47 µ. Newtown Square. Pl. [27], Fig. 8.