6 Acta Societatis pro Fauna et Flora fennica. VIII, n. 2. 



median line, except around the central nodule, where is a tole- 

 rably large and transversely dilated area. 

 " PL II, fig. 4. 



Lim. 23. 



Foss. Sa. 99. 



This small species stands alone among the other Naviculas, 

 so that if I place this form here in the section of the formosee, 

 it is only with great hesitation. The structure of the valve is 

 extremely delicate, and I am greatly obliged to Prof. Van Hearck. 

 who was so kind as to help me in resolving the striation and 

 sent me a photograph, which however was not distinct enough to 

 be reproduced. 



Sectio: Decipientes. 



N. Semen Ehb. - Donk. B. D. Ill, 8, Grun. F. Jos. Land I, 34. 



Foss. Ta. 97, Ob. 92, Lk. 93. 



N. Bacillum Ehb. — V. H. XIII, 8. 



Ab. 36, Lad. 86, Kon. 41, Sb. 8, 10. 



Foss. Ob. 92. 



N. lepida Greg. — V. H. XIII, 12. 



The fig. in V. H. is too small and indistinct to admit of 

 identification. One specimen from Finland is 0,022 m. m. in lenght 

 and 0,oi m. m. in breadth. The striae are 24 in 0,oi m. m., 

 except in the middle of the valve, where they are stronger and 

 more distant. 



Ab. 36, 47. 



N. Pseudobacillum Grun. — V. H. XIII, 9. 



Ab. 36, Lad. 85, Kon. 40. 



Foss. Ob. 92, Lk. 93, 104. 



N. bacilliformis Grun. — V. H. XIII, 11. 



Ab. 36, 49, Sb. 4, 10. 



Foss. Lk. 104. 



N. pupula Kiitz. — V. H. XIII, 15, 16. 



Ab. 36, 46, 47, 48, Sb. 2, 5, 8, 10, 16, Lt. 31, 33. Lim. 23, 26. 



Foss. Tb. 90, Ob. 91, 92, Lk. 93, 104. 



N. americana Ehb. — V. H. XII, 37. 



Ab. 36. 



Foss. Ta. 94, 95, 97, Tb. 90. 



