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82 p. T. CLEVE, SYNOPSIS OP THE NAVICDLOID DIATOMS. 



- ( Striae 6 in 0,oi mm P. Thorax Brun. 



' \ — 13 — — . .P. lignitica Ol. 



Valve narrow lanceolate ... . .P. subsolaris Geun. 



— linear . . . 7. 



_ I Ends subcapitate . 8. 



\ — rounded . ... . . . 12. 



„ I Central area broad . . . . . . ... P. stauroptera Geun. 



'\ — • — narrow ... . ... 9. 



. I Valve large. L. 0,i to 0,2 mm. . • ... .... 10. 



"I — smaller. L. 0,05 to 0,08 mm. . . ... 11. 



..„ j Axial area very narrow ... P. luculenta A. S. 



/ Axia 



"{' 



V3 as broad as the valve . ' .P. Tabellaria Ehb. 



Central area small . . ..... . . . P. gibba Ehb. 



large . . . ... P. mesogongyla Ehb. 



.j„ j Striae parallel . . P. spitsbergensis Cl. 



..„ J Striae 8 to 10 in 0,01 mm. . . ... P. rangoonensis Geun. 



radiate ... . . . . 13. 



12 in — — . ... ... P. bogotensis Gbun. 



27. P. spitsbergensis Cl. N. Sp. — V. linear, with parallel margins and rounded ends. 

 L. 0,058 to 0,067; B. 0,oo7 to 0,008 mm. Median line filiform with somewhat distant, bayonet- 

 shaped, terminal fissures. Axial area distinct, less than '/a of the breadth of the valve, linear, 

 slightly widened around the central nodule, or transversely dilated to a fascia. Striee 16 to 17 

 in 0,01 mm., almost parallel. — PI. I f. 13. 



Fresh water: Spitsbergen (Cl. M. D. N:o 159), Jenissey! 



Var. stomatophora Cl. — Central area with a linear marking on each side of the central 

 nodule. — Fresh water: Spitsbergen. 



28. P. luculenta A. S. (1876). — V. linear, slightly gibbous in the middle and at the ends. 

 L. 0,1; B. 0,014 mm. Median line filiform, with approximate central pores, and bayonet-shaped 

 terminal fissures. Axial area very narrow; central area small, orbicular. Strise 13 in 0,oi mm. 

 strongly divergent in the middle and convergent at the ends. — Nav. luculenta A. S. Atl. XLIII f. 12. 



Fresh water: Bengal (Kyan-Zoo, Atl.). 



29. P. gibba (Ehb.?) W. Sm. (1853). — V. linear, gradually tapering from the middle to 

 the subcapitate ends. L. 0,o^ to 0,o8; B. 0,oo7 to 0,oo8 mm. Median line filiform, with approxi- 

 mate median pores and slightly curved terminal fissures. Axial area narrow, linear, slightly 

 dilated in the middle. Striae 10 to 11 in 0,oi mm. slightly divergent in the middle and convergent 

 at the ends, frequently interrupted in the middle. — ■ Stauroptera gibba Ehb. Am. I: 2 f . 3 (1843)? 

 P. gibba W. Sm. B. D. i PI. XIX f. 180. Nav. Froserpince Pant. Ill PL XVIII f. 260 (1893). 

 Nav. appendiculata Pant. Ill PI. Ill f. 46 (1893)? 



Fresh water: England (Cornwall)! Scotland (W. Sm.), Ireland (Mourne Mountains)! Austra- 

 lia (Blue Mountains)! N. America (Waterford, Maine)! Brazil (Caldas)! 



30. P. stauroptera Grun. (1860). — V. slender, gradually tapering from the middle to 

 the subcapitate ends. L. 0,0 9 to 0,12; B. 0,oi2 to 0,oi3 mm. Median line filiform, with approxi- 

 mate median pores and slightly curved terminal fissures. Area wide, about a third of the breadth 

 of the valve. Striae 9,5 to 10 in 0,oi mm. strongly divergent in the middle and convergent at 

 the ends. — Nav. stauroptera Grun. Verh. 1860 p. 516. Nav. gibba Done. B. D. p. 70 PL XII 

 f. 3. A. S. Atl. XLV f. 48 to 50. Nav. gibba var. hyalina H^rib. a. Perag. D. d'Auvergne p. 92 

 PL IV f. 14. 



Fresh water: Iceland! Sweden! Norway (Stavanger, foss.)! Finland! Holstein! Australia 

 (Murray River, Blue Mountains)! N. America (Canada, Massachusetts, New Hampshire, Sierra 

 Nevada)! Brazil! 



