THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 125 



SURIRELLA SPLENDIDA (EHR.) KUETZ. 



Valve ovate; costse, 1J^ to 2 in 10 n; pseudoraphe linear, narrow. L. 125-200 pi- 

 Fresh water. 

 PI. 35, Fig. 3. 



S. splendida is smaller than S. robusta and wider in proportion, but, as intermediate 

 forms occur, it is difficult to distinguish between them. 



SURIRELLA ELEGANS EHR. 



Valve ovate, rounded at one end and acute at the other; pseudoraphe lanceolate, 

 narrow; costae, \}/<i in 10 M! striae subtle, 22 in 10 M- Frustule in zone view cuneate. 

 L. 180-220 M- 



Fresh water. 



PI. 36, Fig. 1. 



SURIRELLA STRIATULA TURPIN 



Valve broad, obovate or elliptical, rounded at each end; costse, 1J4 in 10 n, curved at 

 the ends; striae, 14 in 10 //. Frustule in zone view cuneate; marginal alas quite robust. 

 L. 100-160 /i. 



Blue clay. Brackish water. 



PI. 34, Fig. 1. 



In the specimen figured, the outline is exactly elliptical, although the species is usually 

 conical at one end. 



SURIRELLA GEMMA EHR. 



Valve ovate or ovate-elliptical, rounded at each end, sometimes asymmetrical along 

 the longitudinal axis; pseudoraphe very narrow; costse distant, at irregular intervals, 

 about 2 in 10 //, somewhat radiate, reaching the pseudoraphe; strise, 20 in 10 n, punctate. 

 Frustule in zone view cuneate. L. 70-120 p. 



Along the coast. 



PL 36, Fig. 4. 



SURIRELLA TENERA GREG. 



Valve ovate; pseudoraphe narrow, well-defined; costse indistinct, 2% in 10 /LI, their 

 margins invisible; striae about 14 in 10 p. punctate, more evident near the margin. L. 90 /i. 



Surirella diaphana Bleisch. 



Pavonia. N. J., artesian well. 



PL 35, Fig. 6. 



The figure is that of the var. nervosa A. S. (Atlas, PL 23, Fig. 15), which differs from 

 the type in having the position of the costse indicated by scattered puncta. 



