Lyratæ Cl.
Valve elliptical or elliptical-lanceolate; striæ punctate, transverse; axial area narrow or indistinct; central area expanded on each side into lyre-shaped or horn-like blank spaces.
NAVICULA PRÆTEXTA EHR.
Valve elliptical; lateral areas not regular, with scattered puncta; striæ radiate, 5 or 6 in 10 µ; puncta, 7 or 8 in 10 µ; along the axial area, a single or double row of puncta; at the middle of the border, on each side, two striæ approach each other closely with a short stria between them; terminal fissures small, in the same direction. L. 120 µ.
Port Penn, Delaware River.
Pl. [24], Fig. 2.
While variable in size and striation, approaching N. hennedyi, this species, as here figured, is found in the Miocene and later deposits and is extant in most parts of the world.
NAVICULA IRRORATA GREV.
Valve oblong-elliptical, with cuneate-rostrate ends; striæ, 7 or 8 in 10 µ, puncta, 7 in 10 µ; axial area bordered by puncta in unequal, transverse rows. L. 84 µ.
Blue clay. Rare.