Valve elliptical; furrows broad, crossed with rows of faint costæ and alveoli; costæ, 6 or 7 in 10 µ; alveoli, 10 in 10 µ, in short, irregular, longitudinal rows. L. 84 µ. Port Penn, Delaware River. Pl. 20, Fig. 11. DIPLONEIS GRUENDLERI (A. S.) CL. Valve constricted, segments tongue-shaped, often unequal; horns broad, divergent in the middle; furrows narrow; costæ transverse, crossed by from 3 to 7 longitudinal costæ, interrupted in the middle at the border. Blue clay. Pl. 20, Figs. 7 and 8. DIPLONEIS PUELLA (SCHUM.) CL. Valve elliptical, sometimes orbicular; furrows very narrow; striæ, 20 in 10 µ, indistinct. L. 15 µ. _Diploneis elliptica_ var. _minutissima_ Grun. Shark River, N. J. Brackish. Pl. 20, Fig. 12. DIPLONEIS EXCENTRICA, N. SP. Valve elliptical; central nodule quadrate; furrows of the same width throughout, nearly parallel; costæ radiating toward the ends, 10 in 10 µ, indistinct on the furrows, alternating with alveoli, 7 in 10 µ, in irregular, longitudinal lines. One side of the valve is one and a half times the width of the other. L. 49 µ. {86}I can find neither description nor figure of any species to which I can ascribe this form. It approaches D. elliptica. The alveoli are quite distinct and distant from each other. Brackish water. Very abundant in a gathering from Squan River, N. J. Pl. 20, Fig. 10. DIPLONEIS OCULATA (BRÉB.) CL. Valve elliptical; striæ radiate at the ends, about 20 in 10 µ, coarsely punctate. L. 23 µ. Fresh water. Pl. 26, Fig. 7. The figure is drawn from Brébisson's original material in H. L. Smith's Type Slide No. 299. _Navicula oculata_ Bréb. Reported from New Jersey. I have not seen this species in this locality. Navicula oculata, referred to by Kain as occurring in Shark River, is not this form. DIPLONEIS GEMMATA (GREV.) CL. Valve oblong-linear, with cuneate ends and parallel or slightly concave sides; central nodule large; horns parallel; furrows about one-third the width of the valve. Costæ about 5 in 10 µ, alternating with double rows of fine puncta; short costæ occur along the borders of the horns. Port Penn, Delaware River. Pl. 20, Fig. 16. DIPLONEIS CAMPYLODISCUS (GRUN.) CL. Valve suborbicular; central nodule quadrate; horns divergent; costæ, 6 in 10 µ, alternating with double rows of alveoli; furrows broad, costate near the horns. Differs from Cleve's description in having 6, instead of 4, costæ in 10 µ. Pensauken, N. J. (artesian well). Rare. Pl. 20, Fig. 6. MASTOGLOIA THWAITES (1856) (mastos, a breast, and gloios, gelatinous, referring to the "mamillate cushion" in which the frustules are often immersed) Frustule rectangular. Valves similar, naviculoid. Central and axial areas usually narrow or indistinct; striæ punctate, parallel in the middle. On each side, between the valve and the zone, is a septate plate. ANALYSIS OF SPECIES