Valve clavate, with cuneate, acute apex; axial area distinct; central area unilateral with one stigma. Blue clay. Pl. 19, Fig. 11. GOMPHONEMA ACUMINATUM VAR. TURRIS (EHR.) CL. Valve clavate, with cuneate apiculate apex and narrow basis; axial area narrow, with a unilateral central space; stigma opposite the short striæ; striæ more radiate in the upper part, distant in the middle. Smith's Island, Delaware River. Pl. 19, Fig. 5. GOMPHONEMA ACUMINATUM VAR. CORONATA (EHR.) CL. Valve twice constricted, with broad, cuneate apex; striæ radiate in the middle, convergent near the apex and radiate at the apex. Variable in size and outline. Blue clay. Fresh water. Common. Pl. 19, Fig. 7. GOMPHONEMA ACUMINATUM VAR. TRIGONOCEPHALA (EHR.) CL. Valve broad, with cuneate apex; axial area narrow; central area unilateral with one stigma. Pavonia, N. J., artesian well. Pl. 19, Fig. 20. {72}GOMPHONEMA CONSTRICTUM EHR. Valve clavate, constricted beneath the abruptly rounded apex, gibbous in the middle, striæ alternately longer and shorter; axial area narrow, central area unilateral, with one stigma. Common in fresh water. Pl. 19, Fig. 8. GOMPHONEMA SPHÆROPHORUM EHR. Valve clavate, with capitate or rostrate-capitate apex and narrow basis; axial area very narrow; central area small, unilateral, with one stigma. Common in fresh water. Pl. 19, Figs. 9 and 10. Fig. 10 appears to be a transitional form having a more distinct axial area and rostrate apex. GOMPHONEMA AUGUR EHR. Valve broadly clavate, truncate and apiculate at the apex; basis sub-acute; axial area distinct; central area small, unilateral with one stigma; striæ with distant puncta. Blue clay. Willistown, Pa. Pl. 19, Fig. 21. GOMPHONEMA INTRICATUM KUETZ. Valve narrow, lanceolate, slightly gibbous in the middle; axial area distinct; central area transverse with one stigma; striæ parallel. Quite variable. Common in fresh water. Pl. 19, Fig. 14. GOMPHONEMA ANGUSTATUM KUETZ. Valve lanceolate, with sub-rostrate apex and basis; axial area indistinct; central area unilateral, with one small stigma; striæ slightly radiate, indistinctly punctate. Very common in fresh water. Pl. 19, Figs. 18 and 19. Fig. 19, as stated above, represents the formation of an auxospore. GOMPHONEMA ÆQUALE GREG. Valve linear-lanceolate, nearly symmetrical, with capitate apex and basis; axial area narrow; central area unilateral, with one stigma; striæ radiate in the middle, slightly convergent at the ends. _Gomphonema intricatum var. æquale_ (Greg.) Cl. Blue clay. Not common. Pl. 19, Fig. 15. GOMPHONEMA SARCOPHAGUS GREG. Valve linear, irregular in outline, with rounded apex and basis; axial area distinct; central area small, unilateral, with one stigma; striæ irregular with coarse, distinct puncta. Occasional in fresh water. Pl. 19, Fig. 16. GOMPHONEMA CAPITATUM EHR.