The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

SURIRELLA PINNATA WM. SM.

Valve ovate or oblong-ovate; costæ reaching the linear pseudoraphe, about 6 in 10 µ. L. 40 µ.

Surirella ovalis var. pinnata (Wm. Sm.) De Toni.

S. pinnata is the type of a number of small forms usually found together, including S. panduriformis, S. angusta and S. minuta.

Fresh water. Media (Palmer).

Pl. [36], Fig. 7; Fig. 9 (abnormal).

Var. minuta, a small form of S. pinnata, occurs with the type.

SURIRELLA PANDURIFORMIS WM. SM.

Valve linear-oblong, with rounded ends, more or less constricted in the middle; otherwise as in S. pinnata. L. 54 µ.

Fresh water.