THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 91 



NAVICULA LATISSIMA VAR. ELONGATA (PANT.) CL. 



Valve elliptical-lanceolate, with rounded ends; striae and puncta closer than in the 

 type form; axial area narrow, widened in the middle; terminal fissures hook-shaped, turned 

 in different directions. 



Navicula humerosa var. elongata Pant. 



Fossil at Buckshutem, N. J. 



PI. 24, Fig. 5. 



NAVICULA FUCHSII PANT. 



Valve elliptical, with slightly produced apices; axial area wide, lanceolate; central 

 area orbicular; strise alternately longer and shorter in the middle, 10-12 in 10 ju; puncta on 

 the border of the axial area larger, elongated ; median fissures incrassate. 



Navicula humerosa var. fuchsii (Pant.) Cl. 



Navicula (lalissima var.?) fuchsii Pant. 



Port Penn, Delaware River. 



PI. 24, Fig. 6. 



NAVICULA HUMEROSA BREB. 



Valve lanceolate-elliptical or oblong-elliptical, with sub-cuneate or sub-rostrate ends; 

 axial area narrow, lanceolate; central area rounded, somewhat transverse; terminal fissures 

 hook-shaped, in the same direction; central pores incrassate; striae, 11 in 10 n, the middle 

 alternately longer and shorter, closer at the ends. L. 60-86 /u. Variable in size, outline 

 and fineness of striation. 



N. monilifera Cleve (N. granulata Breb.) differs in having coarser strise. 



Blue clay. Along the coast. 



PL 25, Fig. 5. 



NAVICULA PUSILLA WM. SM. 



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

 area elliptical; striae radiate, 10-12 in 10 n in the middle where they are longer and shorter 

 alternately, closer at the ends; median fissures somewhat incrassate, terminal in the same 

 direction. L. 47 ju. 



Smith's Island, Delaware River. 



PL 25, Figs. 4, 6 ? 



Cleve gives the striae as 13-18 in the typical form, and 11-13 in varieties. In the form 

 here figured the striation is as stated by De Toni, but is about 19 at the ends. 



Fig. 6 appears to be a small form of N. pusilla, near lanceolata Grun., at least accord- 

 ing to the figure in "Arctic Diatoms," but not Gregory's figure. It occurs rarely in fresh 

 water at Newtown Square. It may be a small form of N. punctulata and, if so, is probably 

 accidental, as the material is entirely fresh-water. 



NAVICULA PUSILLA VAR. SUBCAPITATA N. VAR. 



Valve elliptical with rostrate-capitate and truncate ends; striae about 12 in 10 M in 

 the middle where they are unequal; axial area narrow, slightly widened in the middle; 

 central pores incrassate, terminal fissures in the same direction. Differs from type in out- 

 line and centre. 



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



PL 25, Fig. 8. 



