KONGL. SV. VET. AKADEMIENS HANDLINGAR."^BAND 27. N:0 3. 81 



Var. scalaris Ehb. (1843). — Narrow, linear. Central area a broad transverse fascia. — 

 Stauroptera scalaris Ehb. Am. IV: 2 f. 3. Nai\ borealis var. scalaris GtRUN. Verb. 1860 p. 518 

 Pl. IV f. 15. 



Labrador (Ehb.). 



Pinn. iorealis graduates by intermediate forms into P. lata. 



25. P. lata Bréb. (1838). — V. linear-elliptical, with broad, rounded ends. L. 0,1 to 0,i3; 

 B. 0,03 to 0,04 mm. Median line oblique; central pores approximate, terminal fissures hook-shaped. 

 Area large, sligbtly vvidened in the middle. Strite slightly radiate in the middle, 3 in 0,oi mm., 

 transverse at the ends. — Frustulia lata Bréb. Cons. p. 18. P. lata W. Sm. B. D. I pl. XVIII 

 f. 167. Nav. lata Kutz Bac. p. 92. Grun. Franz Jos. Land D. p. 98 Pl. I f. 14. Nav. lata 

 var. minor Hérib. a. Perag. D. d'Auvergne p. 86 Pl. IV f". 5. P. megaloptera Ehb. M. G. III: i 

 f. 4; IV: 2 f. 5 (1854). Abh. 1870 Pl. III f. 16. Nav. meg. Hérib. D. d'Auvergne p. 88 Pl. IV 

 f. 6. P. pachyptera Ehb. Am. p. 133 Pl. IV: a f. 9 (1843). Nav. pach. A. S. Atl. XLV f. 5, 8. 

 Pant. III Pl. XX f. 302. Nav. costata Hérib. D. d'Auvergne p. 87 Pl. IV f. 7 (1893). 



Fresh water: Franz Josefs Land (Grun.), England! Scotland! Ireland! France (Normandy)! 

 Switzerland! Australia (Murray River)! New Zealand! Hungary fossil. 



Var. RabenJiorstii Grun. (1860). — V. slightly constricted in the middle, with cuneate, 

 truncate ends. L. 0,06; B. 0,oi5 mm. Striis parallel, 4 in 0,oi mm. — Nav. Thuringiaca Habh. 

 Fl. E. A. p. 205. Nav. Rahenhorstii Grun. Verh. 1860 p. 515, Pl. IV f. 13. Nav. Iorealis var. 

 fossilis Pant. Ill Pl. V f. 73 (1893). 



Fresh water: Thuringen (Rabh.). 



Var. latestriata Greg. (1854). - V. narrow-linear, with subcuneate extremities. L. 0,04 to 

 0,06; B. 0,0 12 mm. Striai 4 in 0,oi mm. — Pinn. latestr. Greg. M. J. II p. 98 Pl. IV f. 12. 

 Nav. borealis var.? producta Grun. Verh. 1860 p. 518 Pl. IV f. 14. 



Fresh water: Mull Dept. 



Var. minor Grun. (1878). — L. 0,045; B. 0,oi3 mm. Area narrow. Striee 4 — 5 in 0, 01 mm. 

 — Grun. Cap. S. Alg. Pl. IV f. 22. Fr. Jos. L. D. p. 98 Pl. I f. 16, 17. Nav. lata V. H. S. 

 p. 76 Pl. VI f. 1-2. 



Fresh water: Spitsbergen! Franz Jos. Land (Grun.), Casp. Sea (Grun.). 



Var. curta Grun. (1884). — V. elliptical. — Grun. Fr. Jos. L. D. f. 15. 



Fresh water: Franz Jos. Land (Grun.). 



26. P. alpina W. Sm. (1853). — V. elliptic-lanceolate, with rounded, obtu.se ends. L. 0,i 

 to 0,18; B. 0,038 to 0,05 mm. Median line oblique; central nodule large; terminal fissures spirally 

 twisted. Axial area wide (less than V3 of the breadth of the valve) lanceolate. Striai radiate, 3,5 

 in 0,01 mm., transverse at the ends. — B. D. I p. 55 XVIII i. 168. Nav. alpina Uonk. B. D. 

 p. 27 IV f. 6. A. S. Atl. XLV f. 1 to 4. 



Fresh water (subalpine regions): Scotland! Ireland! Erzgebii'ge! Switzerland! 



V. Tabellariese. 



Artificial hey. 



J Central area with a linear mark on eacli side of the central nodule 2. 



' \ — — without — — — — — — 3. 



I Valve not nndulate P- stomatophora Geun. 



\ — slightly triundulate P. Brandelii Cl. 



J Valve lanceolate, broad 4. 



\ — linear, narrow 6. 



■ Large. L. 0,i-i to O.is mm P. Sillimanorum Ehb. 



Small. L. 0,04 to 0,07 5 mm • 5. 



K. Sv. Vet. Akad. Haadl. Band 27. N:o 3. 11 



