Pl. [19], Fig. 7.
GOMPHONEMA ACUMINATUM VAR. TRIGONOCEPHALA (EHR.) CL.
Valve broad, with cuneate apex; axial area narrow; central area unilateral with one stigma.
Pavonia, N. J., artesian well.
Pl. [19], Fig. 20.
GOMPHONEMA CONSTRICTUM EHR.
Valve clavate, constricted beneath the abruptly rounded apex, gibbous in the middle, striæ alternately longer and shorter; axial area narrow, central area unilateral, with one stigma.
Common in fresh water.
Pl. [19], Fig. 8.
GOMPHONEMA SPHÆROPHORUM EHR.