Valve lanceolate, obtuse; axial area widened in the middle; striæ radiate in the middle, about 12 in 10 µ, transverse or slightly convergent at the ends. L. 45-60 µ. Occurs in gelatinous tubes; usually found free. _Colletonema neglectum_ Thwaites. Fresh water. Pl. 26, Fig. 19. NAVICULA RAMOSISSIMA (AG.) CL. Valve lanceolate, sub-acute; axial area very narrow; central area scarcely widened; striæ, 12 in 10 µ, parallel throughout. L. 45 µ. _Micromega ramosissimum_ Ag. _Schizonema smithii_ Kuetz. (not Ag.). East River, N. Y. Pl. 26, Fig. 14. {96}NAVICULA ANGLICA RALFS Valve elliptical, with sub-capitate or rostrate ends; axial area narrow, central area small; striæ radiate, 12-13 in 10 µ, distinctly punctate. L. 26 µ. Fresh water. Pl. 26, Fig. 26. NAVICULA GASTRUM EHR. Valve elliptical, with rostrate ends; axial area narrow, central area transverse or irregular; striæ radiate, 9 in 10 µ in the middle. L. 26 µ. The form here figured approaches N. anglica. Kirkwood Pond, N. J. Pl. 26, Fig. 25. NAVICULA DICEPHALA WM. SM. Valve linear, with rostrate or rostrate-capitate ends; axial area narrow, central area rectangular, transverse; striæ radiate, 12 in 10 µ. L. 32 µ. Fresh water. Pl. 27, Fig. 16. NAVICULA HUMILIS DONK. Valve elliptical, with broad, rostrate ends; axial area narrow; central area small; striæ radiate and distant in the middle, convergent at the ends, coarse, appearing costate, averaging 9 in 10 µ. L. 19 µ. As Donkin states, the striæ are "very conspicuous." _Navicula hungarica_ var. _capitata_ (Ehr.) Cl. _Navicula globiceps_ Lagerstedt, according to Cleve. Willistown, Pa. Pl. 27, Fig. 24. NAVICULA PINNATA PANT. ? Valve lanceolate, obtuse; axial area narrow, widened in the middle; striæ coarse, 7 in 10 µ in the middle, radiate, 10 in 10 µ at the ends and transverse, indistinctly lineate. L. 40 µ. Near _Navicula ardua_ Mann (Diat. Albatross Voy., Cont. U. S. Nat. Herbarium Vol. 10, Part 5, p. 336, Pl. 53, Fig. 2) which, however, is said to have "strictly unbeaded costæ." Pavonia, N. J., artesian well. Pl. 27, Fig. 20. NAVICULA PENNATA A. S. Valve lanceolate, acute; axial area narrow; central area quadrate, transverse; striæ radiate, coarse, 5 in 10 µ, lineate. L. 68-95 µ (Cleve). Pavonia, N. J., artesian well. Pl. 27, Fig. 22. NAVICULA INFLEXA GREG. Valve slightly elliptical-lanceolate, sub-acute, smooth at the ends; axial area narrow, widened in the middle; striæ radiate, 11 in 10 µ, lineate. Frustule in zone view constricted in the middle. L. 28-45 µ. Common along the coast. Pl. 27, Figs. 18 and 19. {97}NAVICULA OBLONGA KUETZ. Valve linear-lanceolate, with broad, rounded ends; margin sometimes undulate; axial area narrow; central area large, orbicular; striæ in the middle distant, radiate, convergent at the ends and curved or sharply bent, 7 in 10 µ, lineate. L. 70-200 µ (Cleve). Blue clay. Occasional in fresh water. Pl. 27, Fig. 21. NAVICULA HASTA PANT.