The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

MELOSEIRA ROESEANA RAB.

Frustules cylindrical, constricted toward each end, with coarse, longitudinal striæ; valve convex, striæ punctate, radiating, with several large granules at the centre. Connective zone with longitudinal rows of fine puncta. Diam. 12-45 µ.

Orthosira spinosa Grev.

Fresh water. Media, Pa. (Palmer); not common.

Pl. [1], Figs. 5 and 6.

MELOSEIRA ROESEANA VAR. EPIDENDRON (EHR.) GRUN.

Frustules denticulate at the margin; valve with coarse granules at the centre from which radiate lines of fine puncta.

Wet rocks of the Wissahickon.

Pl. [1], Figs. 3 and 4.

MELOSEIRA UNDULATA (EHR.) KUETZ.