THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 107 



DlVERGENTES 

 PINNULARIA DIVERGEN3 VAR. ELLIPTICA GRUN. 



Valve linear, with rounded ends; axial area widened in the middle to a transverse 

 fascia; striae, 9 in 10 p., divergent in the middle, convergent at the ends. I.. 150 p. 

 Fresh water. Not common in this locality. 

 PI. 31, Fig. 13. 



PINNULARIA CARDINALICULUS CL. 



Valve linear, with rounded ends ; axial area wide, less than one-third the width of the 

 valve, expanded to a transverse fascia; striae divergent in the middle and slightly conver- 

 gent at the ends, 9 in 10 M- L. 97 /JL. 



Blue clay. 



PL 30, Fig. 1. 



As a rule, the median fissures in Pinnularia are turned inwards on the side of the longer 

 edge of the terminal fissures, but not always. In this specimen the median fissures are 

 turned slightly toward the side of the shorter edge of the terminal fissures. 



PINNULARIA LEGUMEN EHR. 



Valve linear, with more or less triundulate margins and broad, capitate ends ; axial 

 area less than one-fourth the width of valve, widened in the middle; striae strongly 

 divergent in the middle and convergent at the ends, 10 in 10 n- L. 84 p. 



Fresh water. May's Landing, N. J. 



PL 30, Fig. 3. 



PINNULARIA LEGUMEN VAR. ? 



Valve as in type, but with a transverse fascia; striae, 10 in 10 n, curved or bent near the 

 ends. L. 84 ^. 



This form is not var. florentina Grun. 

 May's Landing, N. J. (with the type). 

 PL 30, Fig. 4. 



PINNULARIA BREBISSONII (KUETZ.) CL. 



Valve linear-elliptical, with rounded ends; axial area narrow, widened into a transverse 

 fascia which is usually broader at the ends; striae divergent in the middle, convergent at 

 the ends, about 12 in 10 p. L. 40-60 M (CL). 



Fresh water. Common. 



PL 29, Fig. 12; PL 31, Fig. 11. 



Variable in outline. 



PINNULARIA MORMONORUM (GRUN.) 



Valve linear, with rounded ends; striae divergent in the middle, convergent at the ends, 

 10 in 10 n; axial area rhombic-lanceolate, widened to a fascia usually reaching the border. 

 L. 62 M. 



Navicula mormonorum Grun. 



Common near Willistown, Pa. 



This form is regarded by Cleve as P. brebissonii, but the axial area appears to dis- 

 tinguish it. The valves are sometimes narrowed in the middle. 



PL 29, Fig. 11. 



