NITZSCHIA DUBIA WM. SM.
Valve linear, scarcely, if at all, constricted in the middle, with cuneate, produced, apiculate apices, somewhat recurved; keel very excentric; puncta sometimes partly prolonged, about 9 in 10 µ; striæ, 20-24 in 10 µ. L. 93 µ.
Reported from along the New Jersey coast. I have not seen it. It is generally regarded as fresh-water. Slides sometimes labelled N. dubia are in reality N. litoralis var. delawarensis.
Pl. [39], Fig. 5.
The figure is drawn from a specimen from another locality.
Bilobatæ
NITZSCHIA BILOBATA WM. SM.
Valve linear-lanceolate, constricted in the middle, apiculate at the ends; keel puncta 6 in 10 µ, prolonged unequally across part of the valve, the two median sub-remote; striæ, 16 in 10 µ. Frustule oblong, truncate, constricted in the middle. L. 120 µ.
Shark River, N. J., Chester River, Md.
Pl. [32], Figs. 10 and 11.