Gyrosigma attenuatum (Kuetz.) Cl.
Long Island Sound.
Pl. [23], Fig. 3.
(2) Longitudinal and Transverse Striæ Nearly Equal
GYROSIGMA BALTICUM (EHR.) CL.
Valve with margins parallel nearly to the extremities, which are suddenly unilaterally sub-conical and obtuse; raphe sigmoid; transverse and longitudinal striæ nearly equally distant, 15 in 10 µ (Per.). L. 200-360 µ.
Navicula baltica Ehr.
Pleurosigma balticum (Ehr.) Wm. Sm.
Common along the coast.
Pl. [23], Fig. 2.