Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, lanceolate, widened in the middle; striæ about 10 in 10 µ; in the middle, much closer at the ends; puncta in the middle, 9 in 10 µ, closer and much smaller at the ends. L. 58-95 µ. Cleve (Le Diatomiste, Vol. 2, p. 14) states that this form is very near N. pusilla but is much larger. Specimens from Smith's Island measure 58-65 µ, from Wildwood, 95 µ in length. Pl. 25, Fig. 3. NAVICULA PUNCTULATA WM. SM. Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, central area rounded; striæ, 11 in 10 µ, closer at the ends, a few shorter in the middle; puncta, 10 in 10 µ. L. 54 µ. _Navicula marina_ Ralfs. Port Penn, Delaware River (brackish water). Pl. 25, Fig. 9. "Although this species is described as marine in the Synopsis of Prof. Smith, I have never found it in purely marine localities" (Donkin). NAVICULA PUNCTATA VAR. ASYMMETRICA LAGERSTEDT Valve lanceolate, with rostrate ends; axial area narrow, central area transverse, irregular; striæ radiate, punctate, 12 in 10 µ. L. 36 µ. _Navicula amphibola_ Cleve. Blue clay. Pl. 27, Fig. 15. NAVICULA BRASILIENSIS VAR. BICUNEATA CL., FORMA CONSTRICTA Valve oblong-elliptical, slightly constricted, with cuneate-rostrate ends; axial area narrow; central area dilated transversely and unilaterally; striæ, 9 in 10 µ; puncta closer at the border and in irregular longitudinal rows in the middle; terminal fissures small, hook-shaped, turned in the same direction. L. 93 µ. Corresponds closely to Cleve's variety except in the constriction. Blue clay. Pl. 25, Fig. 2. NAVICULA LACUSTRIS GREG. Valve lanceolate, sub-acute; axial area narrow; central area orbicular; striæ radiate, 14 in 10 µ, punctate, the median puncta sometimes more distant than the others. Blue clay. Rare. Pl. 27, Fig. 12. LYRATÆ CL. Valve elliptical or elliptical-lanceolate; striæ punctate, transverse; axial area narrow or indistinct; central area expanded on each side into lyre-shaped or horn-like blank spaces. NAVICULA PRÆTEXTA EHR. Valve elliptical; lateral areas not regular, with scattered puncta; striæ radiate, 5 or 6 in 10 µ; puncta, 7 or 8 in 10 µ; along the axial area, a single or double row of puncta; at {93}the middle of the border, on each side, two striæ approach each other closely with a short stria between them; terminal fissures small, in the same direction. L. 120 µ. Port Penn, Delaware River. Pl. 24, Fig. 2. While variable in size and striation, approaching N. hennedyi, this species, as here figured, is found in the Miocene and later deposits and is extant in most parts of the world. NAVICULA IRRORATA GREV. Valve oblong-elliptical, with cuneate-rostrate ends; striæ, 7 or 8 in 10 µ, puncta, 7 in 10 µ; axial area bordered by puncta in unequal, transverse rows. L. 84 µ. Blue clay. Rare. Pl. 24, Fig. 4. NAVICULA HENNEDYI WM. SM.