KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 89 



54. P. Flamma A. S. (1876). — V. linear, witli broadly rounded ends. L. 0,i4 to 0,i.'i; 

 B. 0,0 2 5 to 0,0 2 mm. Axial area very narrow, central orbicular. Strise subparallel, flexiTose, in 

 the middle radiate, 7 to 9 in 0,oi mm., crossed by a broad band. — Nar. Flamma A. S. Atl. 

 XLII f. 27, 28. 



Fresb water: Demerara River! 



55. P. Flammula A. S. (1876). — V. linear, witli somewhat dilated and capitate ends. 

 L. 0,1; B. 0,0 15 mm. Axial area narrow, central orbicular. Strise radiate, 9 in 0, 01 mm. — Nav. 

 Flammula A. S. Atl. XLII f. 26. 



Fresb water: Demerara River! 



Seems to be only a smaller form of tbe preceding. 



56. P. oregonica Cl. N. Sp. — V. linear, slightly trinndnlate, witb ciineate, subacute ends.. 

 L. 0,113; B. 0,0 15 mm. Median line filiforin witli approximate median pores, and semicircular 

 terminal fissures. Axial area very narrow, widened in the middle to a rhomboid-lanceolate central 

 area. Strise 11 in 0,oi mm. divergent in the middle, convergent at the ends. — A. S. Atl. XLIIIf. 34. 



Fresh water: Oregon, fossil! 



57. P. major Kutz (1833). — V. slender, linear, gibbous in the middle, and at the rounded 

 ends. L. 0,2 to 0,3; B. 0,o3 mm. Median line not complex, oblique; terminal fissures comma- 

 shaped. Area linear somewhat less than a third of the breadth of the valve, scarcely widened in 

 the middle, convergent at the ends, crossed by a narrow band. — Frustulia major KtJTZ Syn. p. 19 

 f. 25? Nav. maj. Kutz Bac. p. 97 Pl. IV f. 19, 21. Donk. B. D. p. 69 Pl. XI f. 2. V. H. Syn. 

 p. 73 Pl. V f. 3, 4. A. S. Atl. XLII f. 8. 



Fresh water (usually larger lakes): Sweden (Lapland to Skåne)! Finland (Russian Lap- 

 land to Nyland)! No vaja Zemla! France! Switzerland (Lac Leman)! Japan! New Zealand! America 

 (Canada, Albany, Michigan, Washington Territory)! 



Var. linearis Cl. — V. linear, not gibbous in the middle, or ends. Area narrower. Strise 

 7 in 0,01 mm. — finn. maj. W. Sm. B. D. XVIII f. 162. Nav. maj. var. andesitica Pant. III 

 Pl. VII f. 113 (1893). 



Fresh water: Sweden (Lake Rosslängen)! Norway (Stavanger, foss.)! England Sm. Finland 

 (Pudasjärvi, foss.)! Holstein! Germany! Africa (Congo, V. H. CoU.)! America (Monticello New 

 York, Waltham Mass., Demerara)! 



Var. heroina A. S. (1876). — V. gibbous in the middle and at the subcuneate ends. L. 0,26; 

 B. 0,03 5 mm. Median line broad, oblique. Area narrow. Strise 8 in 0, 01 mm. slightly divergent 

 in the middle, and convergent at the ends. Bands indistinct. — Nav. heroina Atl. XLIII f. 2. 



Fresh water: Demerara River! 



Var. asymmetrica Cl. — V. linear, with broad, obtuse ends. L. 0, 14 to 0,26; B. 0, 02 to 0, 03 

 mm. Median line asymmetrical, the two halves of it meeting each other in an obtuse angle. — 

 Pl. I f. 22. 



Fresh water: America (Eralton Lake Canada, Waltham Mass., Crane Pond, Montgomery 

 Alabama) ! 



Var. subacuta Ehb. (1854). — V. linear, with parallel margins and cuneate ends Area 

 narrow. Strise 7 to 7,5 in 0,oi mm. — Pinnul. subacuta Ehb. M. G. XXXV A 6 f. 12. — A. S. 

 Atl. XLIII f. 30 to 32. 



Fresh water: Demerara River! Caldas, Brazil! 



Var. turgiclula Cl. — V. strongly gibbous in the middle and at the ends. L. 0,i7 to 0,28; 

 B. 0,034 to 0,04 mm. Strise 7 to 8 in 0, 01 mm. 



Fresh water: America (Monticello, Troy, Sierra Nevada)! 



This form is very similar to P. latevittata var. Domingensis, from which it differs only by 

 a narrower band across the strise. 



K. Sv. Vet. Akad. Handl. Band 37. N:o 3. 12 



