THE DIATOMACE^E OF PHILADELPHIA AND VICINITY 53 



EUNOTIA (PROPER) 

 EUNOTIA LUNARIS (EHR.) GRUN. 



Frustules sessile, solitary or in clusters. Valve arcuate, narrow, attenuated toward 

 the apices, which are sometimes slightly rostrate or rostrate-capitate; transverse striae, 14 

 in 10 n, punctate. 



Very common in ditches, especially in the spring. Variable in length. 

 PL 12, Figs. 24 and 25. 



EUNOTIA HEMICYCLXJS (EHR.) RALFS 



Valve semicircular, with obtuse apices; striae transverse, punctate; terminal nodules 

 minute and indistinct. 



Hammonton Pond, N. J. Rare. 



PI. 12, Fig. 23. 



The genus Pseudo-Eunotia was created by Grunow for forms like Eunotia, but with- 

 out terminal nodules. As, however, in E. lunaris and E. hemicyclus nodules are evident, 

 although not so large as in many species, I include these two forms as heretofore under 

 Eunotia. 



EUNOTIA BICEPS EHR. 



Valve linear, slightly arcuate, narrow, with rounded apices somewhat revolute; striae, 

 16 in 10 n. 



May's Landing, N. J. 

 PL 13, Fig. 27. 



EUNOTIA PR^ERUPTA EHR. 



Valve convex on dorsal side, apices dilated and truncate; strise distant at centre. 

 Common in the blue clay. 

 PL 13, Fig. 5. 



EUNOTIA PR^ERUPTA VAR. BIDENS GRUN. 



Valve with two undulations; otherwise as in type. 

 Eunotia bigibba Greg. 

 With the type. 

 PL 13, Fig. 19. 



EUNOTIA ROBUSTA RALFS 



Valve arcuate, with several or numerous dorsal ridges or crense which decrease in rela- 

 tive size in proportion to their number. Strise radiate, variable in distance apart, and in 

 size of puncta. 



Ralfs included under this one name the following species named by Ehrenberg: E. 

 diodon (2 crenge); E. triodon (3); E. tetraodon (4); E. pentodon (5); E. diadema (6); 

 E. heptodon (7) ; E. octodon (8) ; E. enneadon (9) ; E. decadon (10) ; E. hendecadon (11) ; E. 

 duodecadon (12); E. serra (13); E. prioritis (14); all more than 20, E. polyodon. 

 E. scalaris,with from 15 to 17 crense, and E. icosodon with 20, may be added. 



It is probable that all of these forms occur at May's Landing, N. J. The forms with 

 more than eight crense are comparatively rare. In the blue clay those with from four to 

 six are most common. 



PL 13, Figs. 13, 14, 15, 16, 17, 21, 24, 25. 



