Valve as in type but with striæ in the middle distinctly punctate and reaching the median line.
Greenwich Point, Philadelphia.
Pl. [27], Fig. 14.
NAVICULA RHYNCOCEPHALA KUETZ.
Valve lanceolate, with produced ends; axial area indistinct; central area small, rounded; striæ radiate in the middle, convergent at the ends, 10-11 in 10 µ, punctate. L. 42 µ.
Fresh water. Common.
Pl. [31], Fig. 8.
NAVICULA CRYPTOCEPHALA KUETZ.
Valve lanceolate, with rostrate ends; axial area indistinct; central area small; striæ, 16 in 10 µ, lineate, radiate in the middle, convergent at the ends. L. 28 µ.
Common in fresh water.