THE DIATOMACEJE OF PHILADELPHIA AND VICINITY 71 



GOMPHONEMA MONTANUM SCHUM. 



Valve slightly biconstricted, with obtuse apex and basis, somewhat cuneate; axial 

 area linear, widened in the middle unilaterally; stigma, one; strise about 11 in 10 //, more 

 distant in the middle, punctate. 



Gomphonema subclavatum var. montana (Schum.) Cl. 



Pavonia, N. J., artesian well. Rare. 



PL 19, Fig. 3. 



GOMPHONEMA GEMINATUM LYNG. 



Valve biconstricted, with large, rounded, sub-truncate apex and broad, sub-truncate 

 basis; strise, 9 in 10 n, radiate in the middle, alternately longer and shorter, transverse at 

 the basis and near the apex where they again radiate, coarsely punctate, puncta, 12 in 10 ju. 

 Axial area linear; central area rounded, with several large stigmas in a longitudinal row; 

 terminal fissures hook-shaped. 



Blue clay. 



PL 19, Fig. 4. 



GOMPHONEMA LANCEOLATUM VAR. INSIGNIS (GREG.) CL. 



Valve lanceolate; axial area narrow; central area unilateral with one stigma; strise 

 with coarse and distant puncta. 



Common and variable. 



Gomphonema insigne Greg. 



PL 19, Figs. 6 and 12. 



Fig. 12 shows a unilateral central area. Fig. 6 is more clavate in outline with small 

 central area. In both forms the coarse puncta are in distinct longitudinal lines in the 

 middle. 



GOMPHONEMA ACUMINATtJM VAR. TURRIS (EHR.) CL.? 



Valve clavate, with cuneate, acute apex; axial area distinct; central area unilateral 

 with one stigma. 

 Blue clay. 

 PL 19, Fig. 11. 



GOMPHONEMA ACUMINATTJM 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 strise; strise more radiate in the upper 

 part, distant in the middle. 



Smith's Island, Delaware River. 



PL 19, Fig. 5. 



GOMPHONEMA ACUMINATtJM VAR. CORONATA (EHR.) CL. 



Valve twice constricted, with broad, cuneate apex; strise radiate in the middle, conver- 

 gent 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. 



