424 SIR NICHOLAS YERMOLOFF ON NAVICULA AND C YMBELLA. 



convex. Median stria on ventral side with stigm-'^. 

 Areas narrow but distinct. 

 Fig, 16. Cymhella {Encyonema) qracilis-Ccsalii. Herkimer. L. 

 0*05, B. O'COo. Striae 18 in O'Ol mm., radiate, 

 punctate. Ends acute. Median stria on ventral side 

 has a punctum, so that the stria appears to coalesce 

 with nodule. Ventral margin slightly triundulatc, 

 dorsal margin convex. Areas distinct. Terminal 

 nodules distant from ends. Sometimes more rhom- 

 boidal and more cymbelloid. Resembles Encyonema 

 gracilis. 



,, 17. Cymhella {Encyonema) Cesatii Rabh. Premnay Peat. 

 L. 0-06, B. 0-006. Striae 19 in O'Ol mm., faint, radiate, 

 no punctum on medium stria. No axial area ; central 

 area small and rounded. Very slender, symmetrical, 

 slightly triundulate, especially one of the margins. 

 Terminal nodules distant from ends. 



,, 18. Cymhella microcephala Grun. St. Fiore. L. 0*025, 

 B. 0*004. Striae about 25 in 0*01 mm., very faint, 

 nearly parallel. Ends rostrate-capitate. Areas in- 

 distinct. Asymmetrical. 



,, 19. Cymhella microcephala Grun. Premnay Peat. L. 0*03. 

 Striae 25 in 0*01 mm., faint, punctate, nearly parallel. 

 Asymmetrical, ends rostrate-capitate. Areas distinct. 



Journ. Quckelt Microscopical Club, Ser. 2, Vol. II J I., So. 83, November I'Jli. 



