The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

Blue clay. Along the coast.

Pl. [6], Fig. 7 and probably Fig. 8.

BIDDULPHIA RETICULUM (EHR.)

Frustule quadrangular. Valve triangular with straight or concave sides and rounded angles. Surface convex at the centre and angles. Markings of unequal size, mostly larger at the centre, scattered; at the angles, small puncta in longitudinal rows.

Triceratium sculptum Shad.

Triceratium punctatum Br.

Triceratium obtusum Br.

For explanation of the synonymy see "Biddulphoid Forms of N. A. Diat.," Proc. Acad. Nat. Sci., 1900, p. 724.

Blue clay. Along the coast.

Pl. [6], Fig. 5.