92 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 



NAVICULA DELAWARENSIS GRTJN. 



Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, lanceolate, 

 widened in the middle; striae about 10 in 10 M in the middle, much closer at the ends; puncta 

 in the middle, 9 in 10 n, closer and much smaller at the ends. L. 58-95 n- 



Cleve (Le Diatomiste, Vol. 2, p. 14) states that this form is very near N. pusilla but is 

 much larger. Specimens from Smith's Island measure 58-65 n, from Wildwood, 95 /u in 

 length. 



PI. 25, Fig. 3. 



NAVICULA PUNCTULATA WM. SM. 



Valve elliptical-lanceolate, with sub-rostrate ends; axial area narrow, central area 

 rounded; strise, 11 in 10 /*, closer at the ends, a few shorter in the middle; puncta, 10 in 

 10 M . L. 54 fi. 



Navicula marina Ralfs. 



Port Penn, Delaware River (brackish water). 



PL 25, Fig. 9. 



"Although this species is described as marine in the Synopsis of Prof. Smith, I have 

 never found it in purely marine localities" (Donkin). 



NAVICULA PUNCTATA VAR. ASYMMETRICA LAGERSTEDT 



Valve lanceolate, with rostrate ends; axial area narrow, central area transverse, irreg- 

 ular; striae radiate, punctate, 12 in 10 p. L. 36 p. 

 Navicula amphibola Cleve. 

 Blue clay. 

 PL 27, Fig. 15. 



NAVICULA BRASILIENSIS VAR. BICUNEATA CL., FORMA CONSTRICTA 



Valve oblong-elliptical, slightly constricted, with cuneate-rostrate ends; axial area 

 narrow; central area dilated transversely and unilaterally; strise, 9 in 10 M; puncta closer at 

 the border and in irregular longitudinal rows in the middle; terminal fissures small, hook- 

 shaped, turned in the same direction. L. 93 /*. 



Corresponds closely to Cleve's variety except in the constriction. 



Blue clay. 



PL 25, Fig. 2. 



NAVICULA LACUSTRIS GREG. 



Valve lanceolate, sub-acute; axial area narrow; central area orbicular; strise radiate, 

 14 in 10 ju, punctate, the median puncta sometimes more distant than the others. 

 Blue clay. Rare. 

 PL 27, Fig. 12. 



LYRAT^: CL. 



Valve elliptical or elliptical-lanceolate; strise punctate, transverse; axial area narrow 

 or indistinct; central area expanded on each side into lyre-shaped or horn-like blank spaces. 



NAVICULA PR^ETEXTA EHR. 



Valve elliptical; lateral areas not regular, with scattered puncta; strise radiate, 5 or 

 6 in 10 ju; puncta, 7 or 8 in 10 p; along the axial area, a single or double row of puncta; at 



