THE DIATOMACE^ OF PHILADELPHIA AND VICINITY 129 



PODOCYSTIS ADRIATICA KUETZ. 



Valve nearly symmetrical, obovate, with transverse costae about 4 in 10 p, alternating 

 with double rows of coarse puncta; median line distinct, linear. L. 43 M- 

 Podocystis americana Bail. 

 Hell Gate, N. Y. 

 PI. 40, Fig. 6. 



CYMATOPLEURA WM. SM. (issi) 

 (cuma, a wave, and pleura, a side) 



Valve elliptical; surface transversely undulate, with short, marginal costse. Frustule 

 in zone view linear, with undulated sides. 

 Auxospore formation as in Surirella. 



CYMATOPLEURA SOLEA (BREB.) WM. SM. 



Valve oblong, with cuneate apices, constricted in the middle; costae about 6 in 10 n; 

 striae, 10 in 10 /x; pseudoraphe scarcely visible. L. 50-300 p. 

 Blue clay. Common in the Hudson River. 

 PL 34, Figs. 8 and 9. 



CYMATOPLEURA ELLIPTICA (BREB.) WM. SM. 



Valve elliptical; marginal costse short, 3 in 10 M; striae delicate, 18 in 10 n; undulations 

 four or more. L. 70-140 /* 



Blue clay. 



PI. 37, Fig. 1. 



Forma spiralis. Valve ovate, swelled into curved ridges at the lower end, with a con- 

 traction of the valve. 



Port Penn, Delaware River. 



PI. 37, Fig. 2. 



CYMATOPLEURA MARINA LEWIS 



Frustule linear, with numerous undulations, ends apiculate; valve linear-lanceolate, 

 with acute ends; striae transverse, punctate at unequal intervals, from 16-18 in 10 /*. L. 



43 M- 



East River, N. Y. 



PI. 37, Figs. 3 and 4. 



Lewis states that the ends are more or less truncate. I do not find them so. 



CAMPYLODISCUS EHR. (i84i) 

 (campulos, curved like a saddle) 



Valve orbicular or sub-orbicular, with costae or punctate rays converging from the 

 circumference toward the hyaline centre, which sometimes appears like a pseudoraphe. 

 Frustule of two saddle-shaped valves at right angles to each other. The zone view may be 

 of almost any shape according to position. 



Endochrome consists of two bands, each lining the inner surface of each valve. Auxo- 

 spore and conjugation unknown. 



