The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

Pl. [29], Fig. 11.

Brevistriatæ

PINNULARIA ACROSPHÆRIA (BRÉB.) CL.

Valve linear, gibbous in the middle and at the ends; axial area about half the width of the valve; median line with approximate central pores; median area punctate; striæ nearly parallel, radiate at the ends, 9 in 10 µ. L. 32-180 µ (Cl.).

Blue clay. Recent, fresh water.

Pl. [30], Fig. 7.

PINNULARIA ACROSPHÆRIA VAR. TURGIDULA GRUN. ?

Valve strongly gibbous in the middle; ends rounded; striæ, 12-13 in 10 µ. L. 54 µ.

Blue clay, Gloucester, N. J., artesian well.

Pl. [30], Fig. 8.