P. T. Cleve: The Diatoms of Finland. 25 



Foss. Nyl. 87. 



The same form occurs also in a slide of Pudasjarvi deposit, 

 in the Riksmuseum of Stockholm. 



P. brevicostata CI. n. sp. — Valve linear, 0,12 m. m. in 

 length and 0,0 2 m. m. in breadth. Striae almost marginal, short, 

 7,5 in 0,oi m. m. Area very large, more than half of the valve. 

 Raphe almost straight, not complex. 



PL 1, fig. 5. 



Sb. 2, 8, 10, 16. 



Foss. Ta. 97, Tb. 90. 



Var. leptostauron CI. n. var. — A. S. XLIII, 25. — Valve 

 smaller, 0,ot to 0,0 9 5 m. m. in lenght and 0,o 1 3 m. m. in breadth. 

 Striae 10 in 0,oi m. m. interrupted in the middle of the valve. 



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



P. hemiptera Kutz. — Nav. hem. Kutz. Rac. XXX, 11. — 

 A. S. XLIII (26, 27?) 28, XLV, 9 — ? N. instabilis A. S. XLIII, 

 35_40 — ? Pinn. acuminata W. Sm. R. D. XVIII, 164. 



Valve linear-elliptic, sometimes subcuneate, 0,0 6 to 0,0 8 m. 

 m. in length and 0,on to 0,oi3 m. m. in breadth. Striae radiant, 

 often shortened in the middle of the valve, 9 to 10 in 0,oi m. m. 

 Area broad, generally dilated around the central nodule. 



Ab. 36, 37, Sb. 2, 3, 8, 10, 13, Lt. 29, Lim. 20. 



Foss. Ta. 94, 95, 96, 97, 98, Tb. 90, Ob. 92, Lk. 93, 104. 



P. icostauron Ehb. — Nav. icost. Grun. in CI. Gr. A. D. I, 14. 



Ab. 36, Sb. 10, 17. 



Foss. Ta. 97, Lt. 29. 



P. mesogongyla Ehb.? — Rerl. Akad. 1870 II, 16. — A. S. 

 XLV, 45 (without name). — Nav. decurrens CI. Vega XXXVI, 20- 



Valve 5 times as long as broad, gibbous in the middle and 

 tapering to the subcapitate, broad ends. Striae strongly radiant, 

 11 in 0,oi m. m., shortened on the middle ol the valve. Area 

 narrow, dilated around the central nodule. Length 0,0 6 to 0,0 9 

 m. m., breadth 0,oi3 to 0,oi5 m. m. 



PL 1, fig. 11. 



This species resembles in outline P. tabellaria Ehb. (A. S. 

 XLVIII, 4) but the latter is more .slender, has closer striae (14 in 

 0,oi m. m.) and bayonet-shaped end-fissures. 



P. mesogongyla occurs in Tana elf and at Hjerkin (Norway), 



