126 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 



SECTION 2 



SURIRELLA GUATIMALENSIS EHR. 



Valve ovate; pseudoraphe very narrow and indistinct; costae short, marginal, 

 in 10 ju, absent from the rounded end. L. 120 n. 

 Surirella cardinalis Kitton. 

 Smith's Island, Delaware River. 

 PI. 36, Fig. 5. 



SURIRELLA OVALIS BREB. 



Valve ovate; costae short, marginal, radiate, 3-6 in 10 n, often unequal; central area 

 ovate, indistinctly costate; striae scarcely visible, about 18 in 10 M; pseudoraphe narrow. 

 L. 45-93 fi. 



Surirella davidsonii A. S. 



Fresh or brackish water. 



PL 35, Fig. 5; PL 39, Fig. 11. 



The smaller specimen is from the Delaware River, and the larger from the Hudson 

 River. 



SURIRELLA CRUMENA BREB. 



Valve nearly orbicular; costae short, marginal, radiate; pseudoraphe narrow, indis- 

 tinct; central area indistinctly costate, sometimes interrupted. 



On account of the extreme confusion in the names of many forms which appear to be 

 variations of S. oval is, I have followed Van Heurck in retaining the original names as 

 specific. De Toni gives S. crumena as a variety of S. ovalis. 



Fresh and brackish water. Quite common in the Delaware River. 



PL 35, Fig. 4. 



SURIRELLA PINNATA WM. SM. 



Valve ovate or oblong-ovate; costse reaching the linear pseudoraphe, about 6 in 10 p. 

 L. 40 /i. 



Surirella ovalis var. pinnata (Wm. Sm.) De Toni. 



S. pinnata is the type of a number of small forms usually found together, including 

 S. panduriformis, S. angusta and S. minuta. 



Fresh water. Media (Palmer). 



PL 36 ; Fig. 7; Fig. 9 (abnormal). 



Var. minuta, a small form of S. pinnata, occurs with the type. 



SURIRELLA PANDURIFORMIS WM. SM. 



Valve linear-oblong, with rounded ends, more or less constricted in the middle; other- 

 wise as in S. pinnata. L. 54 /u. 

 Fresh water. 

 PL 36, Fig. 6. 



