98 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 



Reported from New Jersey in fresh water. I have not found it. The figure is from 

 a specimen from another locality. 

 PI. 26, Fig. 6. 



NAVICULA MINIMA GRtJN. 



Valve broadly elliptical, 13-15 ju in length; axial area narrow; central area small but 

 with a quadrate pseudo-stauros which is striated; striae, about 28 in 10 p, radiate. 



Agrees closely with N. saugeri var. Grun. in V. H. Synopsis, PI. 14, Fig. 16, said to be 

 intermediate between N. minima and N. atomoides Grun. N. minima var. atomoides Grun. 

 is smaller. 



Common in water-troughs. 



PI. 26, Fig. 13. 



NAVICULA PUPULA VAR. BACILLARIOIDES GRUN. 



Valve linear, with rounded ends; axial area linear, expanding on both sides near the 

 ends of the valve, forming a transverse lunate space; central area small, apparently 

 expanded into a stauros, which, however, is striated; striae, 18 in 10 jt, at the middle, closer 

 at the ends, punctate. L. 54 ju. 



Pavonia, N. J., artesian well. 



PI. 26, Fig. 9. 



BACILLARES CL. 



Valve linear or linear-elliptical, with broad ends; axial area narrow, the median line 

 enclosed in siliceous ribs; striae finely punctate, more distant in the middle. 



NAVICULA BACILLUM EHR. 



Valve linear, with rounded ends; axial area enclosed in siliceous ribs and slightly ex- 

 panded on each side at the ends; terminal nodules incrassate; central area small, elliptical; 

 striae, 15 in 10 p in the middle, transverse, distinctly punctate, closer at the ends L. 47 ju- 



Fresh water. 



PI. 26, Fig. 10. 



Cleve describes the form as having slightly radiate striae in the middle. There is con- 

 siderable difference in the descriptions of Cleve, Donkin, Grunow and Van Heurck, as 

 also in all of the figures. 



NAVICULA AMERICANA EHR. 



Valve oblong-linear, with rounded ends, sometimes slightly constricted; axial area 

 about one-half the width of the valve, dilated in the middle; striae parallel in the middle, 

 radiate at the ends, 15-16 in 10 ju. A punctum is usually found in the central nodule. L. 

 55-154 M . 



Blue clay. Occasional in fresh water. 



PI. 26, Fig. 8. 



DECIPIENTES CL. 



Valve lanceolate, with obtuse ends; axial area narrow; central area orbicular; striae 

 radiate in the middle and more distant. 



NAVICULA SEMEN EHR. 



Valve elliptic-lanceolate, with sub-rostrate, truncate apices; axial area narrow, sin- 



