In zone view, the median line deeply bisects the longitudinal axis, ending in a mucronate central nodule. Connective zone complex. Valve very complex, with ventral margin nearly straight and raphe excentric. Central nodule near the margin, terminal nodules small. Striæ, 35-40 in 10 µ (Cleve). Chromatophore single, on the ventral part. _Amphora mucronata_ H. L. Smith. _Amphora (?) insecta_ Grun. _Auricula insecta_ (Grun.) Cleve. "A rare and very curious pelagic species" (Peragallo, Diat. Villefranche). Prof. H. L. Smith included this form in his first century of "Species Typicæ Diatomacearum," which was issued prior to 1876, the date of publication, in Schmidt's Atlas, of Amphora insecta Grun. Atlantic City, N. J. Rare. Pl. 15, Fig. 2. SCOLIOTROPIS CLEVE (1894) (scolios, twisted, and tropis, a keel) Frustule linear, oblong. Median line sigmoid near the ends. Valve with transverse costæ alternating with two intermediate rows of puncta in oblique lines. SCOLIOTROPIS LATESTRIATA VAR. AMPHORA CLEVE Valve asymmetrical, with the median line curved. Frustule sub-acute at the ends. Median lines not on the same side of each valve of the frustule. Abundant at Cape May, N. J. Not common elsewhere. Pl. 14, Figs. 10 and 11. GOMPHONEIS CLEVE (1894) (gomphos, a peg, and neis (naus)) Valve elongated, asymmetrical to the transverse axis; axial area narrow; central area rounded, stigmatic; striæ radiating, costæ alternating with double rows of fine puncta. An indistinct, longitudinal line near the border. Chromatophores and conjugation have not been determined. {70}GOMPHONEIS HERCULANEUM (EHR.) CL. Valve clavate, with rounded apex; costæ, 13 in 10 µ, alternating with double rows of fine puncta, 22 in 10 µ, in oblique rows; axial area narrow, central area rounded, with one stigma. _Gomphonema capitatum_ Ehr var. _herculaneum_ Ehr., H. L. S., Type Slide No. 177. Common in the blue clay. Pl. 19, Fig. 2. Pl. 38, Fig. 15, zone view of young frustule. GOMPHONEIS MAMILLA (EHR.) CL. Valve lanceolate, with rounded apex and base; striæ costate, 10 in 10 µ, alternating with double rows of fine puncta; axial area linear, sometimes oblique, central area small, with one or more stigmas. Blue clay. Rare. Pl. 19, Fig. 1. In one frustule I noticed one valve with one stigma and the other with four stigmas. The difference between G. mamilla and G. elegans is not very great. In the latter the central area is larger and the longitudinal lines not so near to the margin. The stigmas form a circlet. There appears to be a coincidence in the relation of Gomphoneis to Gomphonema, and that of the true Achnanthes to the group described by Cleve under Achnanthidium. In Gomphoneis and Achnanthes the striation is both costate and punctate while in Gomphonema and Achnanthidium the striation is punctate only. GOMPHONEMA AG. (1824) (gomphos, a peg, and nema, a filament)