The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

Lewis states that the ends are more or less truncate. I do not find them so.

Campylodiscus EHR. (1841)

(campulos, curved like a saddle)

Valve orbicular or sub-orbicular, with costæ or punctate rays converging from the circumference toward the hyaline centre, which sometimes appears like a pseudoraphe. Frustule of two saddle-shaped valves at right angles to each other. The zone view may be of almost any shape according to position.

Endochrome consists of two bands, each lining the inner surface of each valve. Auxospore and conjugation unknown.

CAMPYLODISCUS ECHENEIS EHR.

Valve sub-orbicular, saddle-shaped; costæ indistinct, short, marginal; rows of round or elongated puncta converge toward the lanceolate, hyaline median space. Diam. 80-140 µ.

Campylodiscus argus Bail.

Blue clay. Reservoir at Thompson and Twenty-sixth Sts., Phila.

Pl. [37], Fig. 6.