Valve very convex, linear, with sub-cuneate ends; axial area narrow, expanded in the middle to a transverse fascia reaching the margin; striæ divergent in the middle, convergent at the ends, 16 in 10 µ. L. 60 µ. Fresh water. Pl. 29, Fig. 15. PINNULARIA LEPTOSOMA GRUN. Valve linear, rounded at the ends; axial area narrow; central area a broad transverse fascia; striæ slightly divergent in the middle and convergent at the ends, 17 in 10 µ in the middle, closer at the ends. L. 56 µ. Fresh water. Not common. Pl. 30, Fig. 10. CAPITATÆ PINNULARIA MESOLEPTA EHR. Valve linear, with triundulate margins and capitate ends; axial area narrow, widened in the middle; striæ divergent in the middle, convergent at the ends, about 12 in 10 µ. L. 34 µ. Common in fresh water. Pl. 29, Fig. 13. PINNULARIA MESOLEPTA VAR. STAURONEIFORMIS GRUN. Valve triundulate, capitate; axial area narrow, widened in the middle to a transverse fascia, broader at the margin; striæ strongly divergent in the middle and convergent at the ends, 9-10 in 10 µ. L. 70 µ. Pavonia, N. J., artesian well. Fresh water. Pl. 30, Fig. 20. PINNULARIA SUBCAPITATA GREG. Valve linear or linear-elliptical, with sub-capitate ends; axial area distinct, widened to a transverse fascia in the middle; striæ divergent in the middle, convergent at the ends, 13 in 10 µ. L. 32 µ. Fresh water. Pl. 29, Fig. 20. {106}PINNULARIA SUBCAPITATA VAR. PAUCISTRIATA GRUN. Valve linear-elliptical, with rounded ends; axial area gradually widened into a broad, transverse fascia; striæ divergent in the middle, convergent at the ends, 11-12 in 10 µ. L. 47 µ. Fresh water. Pl. 30, Fig. 16. PINNULARIA TERMES (EHR.) A. S. Valve linear, with concave margins and rostrate-capitate ends; axial area narrow, widened in the middle to an orbicular or sub-quadrate space; striæ divergent in the middle, scarcely, if at all, convergent at the ends, 10 in 10 µ. Pensauken, N. J., artesian well. Pl. 29, Fig. 17. This is, I believe, the form figured by Schmidt (Atlas, Pl. 45, Fig. 67). Cleve refers it to Pinnularia interrupta forma biceps, in which the central space is rhomboid. PINNULARIA TERMES VAR. STAURONEIFORMIS V. H. Valve linear, with concave margins and capitate-rostrate ends; axial area narrow, widened into a rhomboidal fascia, reaching the margin; striæ, 10 in 10 µ, divergent in the middle, convergent at the ends. _Pinnularia interrupta forma stauroneiformis_ Cl. Fresh water. Pl. 29, Fig. 14. PINNULARIA APPENDICULATA (AG.) CL. Valve linear, with subcapitate ends; axial area narrow; central area a transverse fascia; striæ divergent in the middle, convergent at the ends, 16 in 10 µ. L. 43 µ. Fresh water. Marl pits, Lenola, N. J. (Palmer). Pl. 29, Fig. 18. PINNULARIA BRAUNII GRUN. Valve linear-lanceolate, with capitate ends; axial area gradually widened toward the middle and expanded into a fascia reaching the margin; striæ divergent in the middle, convergent at the ends, 11 in 10 µ. L. 52 µ.