10 ASTRID CLEVE, ON RECENT FRESHWATER DIATOMS. 



P. Brébissonii KtJTZ. — V. H. V, 7, A. S. XLIV, 17, 18. 



Length of the val ve O, o 3 to O, o 5 mm. 



Kv. 28, Nu. 14, 17, 19, 25, 37, S.-K. 33, Ke. 49. — Mo- 

 derately common. 



Var. diminuta GrRUN. — V. H. V, 8. 

 Length of the valve O, o 2 mm. 

 Kv. 32. — Rare. 



P. karclica Cl. — Finl. pl. I, 6. 

 Ke. 49. — Eare. 



P. molaris Grun. — P. macra A. S. XLIV, 54. 



Striae 15 in 0,oi mm. Valve 0,03 mm. in length, with 

 more or less (V. 12) narrow axial area. 



Nu. 5, 19, 41, V. 12, Gl. 43. — Somewhat rare. 



P. Braunii Grun. — V. H. VI, 21. 



Kv. 32. — Rare. 



P. subcayitafa Grég. — V. H. VI, 22. 



Kv. 9, 34, 28, Nu. 2, 3, 14, 18, V. 12, Km. 10, 30, Na. 35. 

 Tr. 38, S.-K. 33, Gl. 43, 47, Gl. D. 44, 45. — Frequent. 



Var. Hilseaiia Janisch. — V. H. Suppl. A, 11. 

 Axial area indistinct. 

 S.-K. 7. — Rare. 



P. gracilliina Grég. var. — V. H. VI, 24. 



Kv. 1, 32, Nu. 2, 14, 25, Ks. 15, Km. 10, 30, Gl. 47, Ke. 49. 



— Rather frequent. 



P. diver^entissima Grun. — V. H. VI, 32. 



As typical, I consider the forms which gradually taper 

 towards the ends. 



Kv. 32, Nu. 2, 14, 18, 19, 37, Gl. D. 44, Ke. 49. — Mo- 

 derately frequent. 



Var. subrostrata A. Cl. n. var. — Pl. I, 5. 



Ends of the valve rostrate-capitate. 



Kv. 28, 34, Nu. 2, 5, 37, Ks. 15, Na. 35, V. 12, Gl. D. 45. 



— Moderately frequent. 



P. iiiesolepta Ehb. — A. S. XL V, 52, 53. P. nodulosa KtJTZ. 

 P. interrupta W. Sx\i. 

 Kv. 26, 32, 34, Tr. 38. — Somewhat rare. 



