Valve rhombic-lanceolate; striæ punctate, radiate; pseudoraphe lanceolate; apices smooth.
Blue clay. Along the coast.
Pl. [12], Figs. 12, 13, 14.
Trachysphenia Petit (1877)
(trachys, rough, and sphen, a wedge)
Frustules rectangular. Valve cuneiform with coarse puncta in transverse and longitudinal lines; pseudoraphe narrow, linear. One species only.
TRACHYSPHENIA AUSTRALIS PETIT
Characters of the genus. Valve small; puncta, 6 in 10 µ. Allied to Dimerogramma.
Shark River, N. J. Rare.
Pl. [12], Fig. 15.