I have retained Lewis' name as specific. Lewis, wrongly, I think, ascribes his species to _Navicula trinodis_ Wm. Sm., which is not figured by Smith, but is illustrated by Van Heurck (Syn. Pl. 14, Fig. 31a), and is named by Cleve _Navicula contenta_ var. _biceps_ Arnott. {82}De Toni includes Lewis' name under _Rhoiconeis trinodis_ (Wm. Sm.) Grun. Rhoiconeis is achnanthiform, with frustules arcuate, and the species is named by Cleve _Achnanthes trinodis_ (Arnott). _Caloneis schumanniana_ (Grun.) Cl., to which as a variety Cleve unites Lewis' form, appears to resemble it only in the lunate marks. Fig. 9 represents a single specimen found in the Pavonia deposit and which I believe to be an abnormal form of C. trinodis, differing only in the degree of inflation and in the larger central area. _Navicula trinodis_ var. _inflata_ Schultze, from Staten Island, is the same form figured by Lewis, who states that certain specimens have produced apices. CALONEIS PERMAGNA (BAIL.) CL. Valve lanceolate, with produced apices; median line nearly straight; axial area lanceolate, irregular or slightly unilateral, about half the width of the valve; striæ, 9 in 10 µ, radiate and indistinctly punctate; longitudinal lines double. L. 100-200 µ. _Pinnularia permagna_ Bail. Common in brackish water. Pl. 21, Fig. 1. CALONEIS PERMAGNA VAR. LEWISIANA N. VAR. Valve lanceolate, with undulating sides and sub-cuneate apices; axial area less than one-third the width of the valve; striæ radiate, 12 in 10 µ, indistinctly punctate; longitudinal lines double, closer together than in the type. L. 140 µ. Lewis illustrates this variety in "New and Rare Species," Pl. 2, Fig. 11, and states that it is probably Navicula esox Kuetzing. This is an error, as Kuetzing's species is Pinnularia esox Ehr., a form near P. major. Rather common in the Delaware River. Pl. 21, Fig. 2. CALONEIS FORMOSA (GREG.) CL. Valve lanceolate, with sub-cuneate apices; axial area one-fourth to one-fifth the width of the valve, somewhat unilateral, dilated in the middle; striæ, 12-14 in 10 µ radiate, punctate; longitudinal lines double, distinct. Variable in size and outline. Abundant along the shores of the Delaware River. Pl. 21, Fig. 18. CALONEIS BREVIS VAR. VEXANS (GRUN.) CL. Valve elliptical-lanceolate; apices obtuse; median fissures distant; axial area narrow; central area large, orbicular; longitudinal lines close together, median. Shark River, N. J. Pl. 21, Fig. 5. CALONEIS WARDII CL. Valve linear, ends cuneate; axial area linear; central area dilated to a stauros reaching the margin; striæ parallel, radiate at the ends, 18 in 10 µ; longitudinal lines marginal. Not uncommon in the Delaware River. Pl. 21, Figs. 6 and 7. {83}CALONEIS POWELLII (LEWIS) CL. Valve linear, with cuneate ends; axial area linear; central area large, quadrate, united to the wide longitudinal lines; striæ parallel, smooth, 8 in 10 µ. Long Island (Lewis); Smith's Island, Delaware River.