48 THE DIATOMACE.E OF PHILADELPHIA AND VICINITY 



SYNEDRA BICEPS (KUETZ.) SCHMIDT 



Valve sublanceolate, inflated at the ends, apices rounded ; central space not always 

 distinct; pseudoraphe narrow; strise radiate at the ends. 



This is not Kuetzing's species, if the descriptions and figures are accepted, nor is it 

 H. L. Smith's Type No. 545, which is S. ulna var. danica, nor is it S. biceps Wm. Smith, 

 but it is exactly Schmidt's form (Atlas, PL 303, Figs. 10-15). 



Schuylkill River. 



PI. 11, Fig. 3. 



SYNEDRA DANICA KUETZ. 



Valve lanceolate, suddenly constricted at the rounded apices ; central space frequently 

 absent. 



Very common in streams. 



PI. 11, Fig. 2. 



The figure represents an unusually large form. It differs from S. ulna only in its apices. 



SYNEDRA CAPITATA EHR. 



Valve long, linear, dilated into triangular acute apices; pseudoraphe distinct; striae 

 radiate at the ends. 

 Blue clay. 

 PI. 11, Fig. 8. 



SYNEDRA ACUS KUETZ. 



Valve very narrow, lanceolate, acicular, with obtuse apices. 

 Common in the Schuylkill River. 

 PI. 11, Figs. 9 and 18. 



SYNEDRA GOULARDI BREB. 



Valve constricted in the middle; apices sub-acute, sometimes slightly rostrate or capi- 

 tate; central space evident. 



Neshaminy Creek (Palmer). Blue clay. Cram Creek. 

 PI. 11, Figs. 12 and 13. 



SYNEDRA PULCHELLA (RALFS) KUETZ. 



Valve lanceolate, tapering to the sub-acute, rostrate or slightly capitate apices; dilated 

 at the central hyaline space; pseudoraphe distinct. Very variable in size. 

 Cram Creek. Schuylkill River. Rather common. 

 PI. 11, Figs. 14, 15, 16. 



SYNEDRA PULCHELLA VAR. ABNORMIS MACCHIATI ? 



Valve as in type form, except that one end is curved like a beak, as in S. hamata Wm. 

 Sm., which it resembles. 



Not uncommon in the Schuylkill River. 

 PI. 11, Fig. 17. 



SYNEDRA OXYRHYNCHUS VAR. UNDULATA GRUN. 



Valve linear-lanceolate with produced rostrate apices, asymmetrical, sigmoid; 

 pseudoraphe narrow; pseudo-nodule large. 

 Common in fresh water. 

 PI. 12, Fig. 1. 



