Valve elliptical-lanceolate, inflated in the middle, with produced sub-capitate or rostrate ends separated by diaphragms. Stauros wide, striated at the margins; axial area very narrow; striæ radiate, about 26 (?) in 10 µ, punctate. L. 28 µ. Pavonia, N. J., artesian well. Pl. 39, Fig. 15. In Cleve's description and Van Heurck's figure, the median inflation is "not larger than the others." In the present form the median inflation is wider. STAURONEIS ACUTA WM. SM. Valve rhombic-lanceolate, obtuse; a diaphragm at each end; stauros widened outwards; striæ, 15 or 16 in 10 µ, punctate. L. 130 µ. Blue clay. Pl. 27, Fig. 2. STAURONEIS AMERICANA A. S. Valve elliptical-lanceolate, obtuse; striæ, 14 in 10 µ. L. 119 µ. Pavonia, N. J., artesian well. Rare. The only specimen found is asymmetrical with respect to the transverse axis. On Plate 40, Fig. 4, is illustrated an abnormal form of Stauroneis, apparently near S. acuta, having an elongated central nodule and radiating, curved and coarsely punctate striæ. Blue clay. STAURONEIS SMITHII GRUN. Valve lanceolate, inflated in the middle and at the ends, which have diaphragms and are produced into rostrate apices; stauros reaching the margin; striæ parallel, about 25 in 10 µ (28 to 30, Cleve), distinctly punctate. Not uncommon in meadow pools near Newtown Square. Pl. 27, Fig. 11. STAURONEIS CRUCICULA (GRUN.) CL. Valve lanceolate, with obtuse, produced ends; stauros bifid; striæ, 24 in 10 µ, oblique, parallel to the branches of the stauros, closer at the ends, punctate. L. 32 µ. Newtown Square. East Park Reservoir. Rare. Pl. 27, Fig. 10. NAVICULA BORY (1826) (dim. of navis, a boat) Valve linear to elliptical; ends acute, rounded, rostrate, capitate or truncate; axial area usually distinct; central area distinct, rounded or rarely extended into a transverse fascia; striæ transverse or radiate, punctate; central area not dilated into a transverse stauros nor into horns.