The Diatomaceæ of Philadelphia and Vicinity

by Charles S. Boyer

Common in the blue clay and along the coast.

Pl. [8], Fig. 7 and Pl. [38], Fig. 11.

RHABDONEMA ADRIATICUM KUETZ.

Valve linear-lanceolate, with smooth angles; rows of puncta transverse, the intervals appearing as costæ, as in arcuatum. Foramina, three.

Blue clay in the Pensauken and Pavonia deposits and along the coast.

Pl. [8], Figs. 4, 5 and 6.

Tabellaria Ehr. (1839)

(tabella, a tablet)

Frustules quadrangular, adnate in filaments, frequently found in zig-zag chains, united by a gelatinous isthmus, at length separating. Valve linear, inflated in the middle and at the ends; striæ transverse.

Chromatophores numerous, small, along the zones.