NITZSCHIA NAVICULARIS (BRÉB.) GRUN. Valve elliptical-lanceolate, with acute apices; striæ on one side a double row of large and small puncta, and on the other side radiate short rows of large puncta, 7 in 10 µ; middle of valve hyaline. L. 35-60 µ. Blue clay. Not common. Pl. 32, Fig. 4. NITZSCHIA COMPRESSA (BAIL.) Valve elliptical-lanceolate, sometimes acuminate; striæ, 6 or 7 in 10 µ, coarsely punctate. L. 56 µ. _Pyxidicula compressa_ Bailey. _Nitzschia punctata_ (Wm. Sm.) Grun. _Tryblionella punctata_ Wm. Sm. Common along the coast. Pl. 39, Fig. 7. Var. minor (H. L. Smith).--Valve acuminate; striæ, 8 in 10 µ. L. 22 µ. _Pyxidicula compressa_ var. _minor_ H. L. Smith, Type Slide No. 431. Pl. 39, Fig. 8. The smaller forms occur northward, while the larger are found southward. This is unquestionably Bailey's form, as indicated by his figure and by the fact that it is found everywhere along the coast. Wm. Smith's T. punctata is the same species, although the puncta are smaller. {117}PANDURIFORMES NITZSCHIA PANDURIFORMIS GREG. Valve elliptical, constricted in the middle, with sub-cuneate apices; longitudinal fold, with a punctate longitudinal line; striæ transverse and oblique, 15 in 10 µ; keel puncta, 6 in 10 µ. L. 108 µ. Along the coast. More often found southward. Pl. 39, Fig. 2. NITZSCHIA PANDURIFORMIS VAR. MINOR GRUN. Valve elliptical, constricted in the middle, with cuneate apices; keel puncta, 9 in 10 µ; striæ in transverse and oblique lines about 20 in 10 µ; longitudinal fold bordered by a punctate line. L. 34 µ. Pavonia, N. J., artesian well. Pl. 32, Fig. 5. The var. continua Grun. is reported as occurring in Shark River. It varies in having the longitudinal fold punctate. It is also usually smaller than var. minor. APICULATÆ NITZSCHIA APICULATA (GREG.) GRUN. Valve oblong-linear, with cuneate-apiculate apices; striæ punctate, apparently interrupted or pervious, about 18 in 10 µ. L. 26 µ. Chester River, Md. Pl. 32, Fig. 6. The puncta are continued across the valve, but are less distinct on the fold. The figure shows the entire frustule with the fold on each valve. The valves are sometimes slightly constricted. NITZSCHIA ACUMINATA (WM. SM.) GRUN. Valve linear, sometimes slightly constricted in the middle, with acuminate apices; longitudinal fold entirely without or with indistinct striæ; keel puncta not evident; striæ, 14-15 in 10 µ. L. 82 µ. Port Penn, Delaware River. Pl. 32, Fig. 13. NITZSCHIA PLANA WM. SM. Valve linear; apices acute, slightly constricted in the middle; longitudinal fold further from the keel than the margin, broad, with scattered puncta; striæ subtle, irregular, interrupted, about 18 in 10 µ; keel puncta oblong, 3-6 in 10 µ. L. 100-170 µ. Blue clay. Along the coast. Pl. 32, Fig. 2. {118}PSEUDO-TRYBLIONELLA NITZSCHIA LITORALIS VAR. DELAWARENSIS GRUN.