KONGI.. SV. VKT. AKADEMIENS IIANDLINOAR. HAND 27. N:() 3. H9 



54. P. Flamina A. S. (1876). — V. linear, with l)rua(lly rounded ends. L. 0,m to 0,ir, ; 

 B. 0,02.'-) to 0,02 mm. Axial area very narrow, (central orbicular. Strite subparallel, Hexno.se, in 

 the middle radiate, 7 to 9 in 0,oi mm., cro.s.sed by a broad band. — Nor. Flanivia A. 8. Atl. 

 XLII f. 27, 28. 



Fresh water: Demerara River! 



55. P. Flamnmla A. S. (187()). — V. linear, with somewhat dilated and capitate ends. 

 L. 0,1 ; B. 0,0 15 mm. Axial area narrow, central orbicular. Strite radiate, !) in 0,oi mm. — Nav. 

 Flammula A. S. Atl. XLII f. 2G. 



Fresh water: Demerara River! 



Seems to be only a smaller form of the preceding. 



56. P. oregouica Cl. N. Sp. — V. linear, slightly triundulate, with cuneate, subacute ends. 

 L. 0,113; B. 0,01-) mm. Median line filiform with 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. XLIII f. 34. 



Fresh water: Oregon, fossil! 



57. P. major Ktixz (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, cro.ssed by a narrow band. — FrustuUa major KtJTZ Syn. p. 19 

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

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



Fresh water (usually larger lakes): Sweden (Lapland to Skane)! Finland (Ru.ssian Lap- 

 land to Nyland)! Novaja 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. Striai 

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

 PI. VII f. 113 (1893). 



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

 (Puda.sjarvi, foss.)! Holstein! Germany! Africa (Congo, V. H. Coll.)! 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. Striae 8 in 0,oi mm. slightly divergent 

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



Fresh water: Demerara River! 



Var. asymmetrica Cl. — V. linear, with broad, obtu.se ends. L. 0,i4 to 0,20; B. 0,02 to O.os 

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

 PI. 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. Striae 7 to 7,5 in 0,oi mm. — Pinmd. sitbaciita Ehb. M. Gr. XXXV J. 6 f. 12. — A. S. 

 Atl. XLIII f. 30 to 32. 



Fresh water: Demerara River! Caldas, Brazil! 



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

 B. 0,034 to 0,04 mm. Striai 7 to 8 in 0,oi mm. 



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



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

 a narrower band across the striee. 



K. Sv. Vet. Akud. Hjindl. Bund 27. N:o 3. 12 



