Fresh water.
Pl. [17], Fig. 4.
FRUSTULIA INTERPOSITA (LEWIS) DE TONI
Valve linear-elliptical, rounded at the ends; terminal nodules short.
Navicula interposita Lewis.
Along the coast. Port Penn, Delaware River.
Pl. [17], Fig. 5.
Amphipleura KUETZ. (1844)
(amphi, on both sides, pleura, a side)
Frustules free, in gelatinous masses or in tubes. Valve linear-lanceolate; central nodule narrow, extending half the length of the valve or more, then forking toward the ends. Terminal nodules prolonged, as in Frustulia, into a "porte-crayon-shaped" figure.