80 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



20. P. Hartleyana Gtrbv. (1865). — V. linear, gibbous in the middle and at the ends. 

 L. 0,2 to 0,23; B. 0,033 to 0,045 mm. Median line straight, filiform. Axial area linear, less than 

 Va as broad as the valve, in the middle transversely dilated, frequently to a fascia. Striae 8 in 

 0,01 mm. divergent in the middle, convergent at the ends. — T. M. S. vol. XIII PI. VI f. 30. 



Fresh water: Liberia (Grev.), Demerara River! 



21. P. episcopalis Cl. (1891). — V. linear, with parallel margins and broad rounded ends. 

 L. 0,23 to 0,36; B. 0,035 to 0,04 mm. Median line filiform with comma-like terminal fissures. 

 Axial area broad, about Vs of the breadth of the valve, in the middle widened to a transverse 

 fascia. Striae 8 in 0,oi mm., strongly divergent in the middle and convergent at the ends. — 

 P. cardinalis Ehb. M. Gr. XVIII: i f. 4. P. episcopalis Cl. D. of Finl. p. 27 PI. I f. 4. 



Fresh water: Sweden (Lake "Wenern, Lake Rosslangen in Kalmar Ian, Ojasjo Dept. in Ble- 

 kinge, interglacial mud from Hernosand)! Finland! Lac Gerardmer, Vosges! Cherryfield, America! 



Var. hrevis Cl. — L. 0,18; B. 0,o38 mm. Striae 6 in 0,oi mm. less radiate. 



Fresh water: New Zealand (Auckland, Witt Coll.)! 



Var. africana Cl. — V. smaller. L. 0,ii5; B. 0,oi8 mm. Axial area less than a third of 

 the breadth of the valve. Striae 8 in 0,oi mm. 



Fresh water, mouth of rivers: Cameroon, Africa! 



P. episcopalis is a very large and beautiful diatom, nearly akin to P. divergens and to 

 P. Hartleyana. 



IV. Distautes. 



Artificial hey. 



I 



\ Length 0,02 to 0,i mm. and more . 3. 



f L. 0,1 



I L. less than 0,i mm. ... ... 4. 



. J Striae 5 to 6 in 0,oi mm ... . . P. horealis Ehb. 



' \ — 8 in 0,01 mm. . . ... P. intermedia Laost. 



22. P. intermedia Lagst. (1873). — V. linear-elliptical, with rounded ends. L. 0,oi8 to 

 0,042; B. 0,06 to 0,08 mm. Axial area narrow; central a transverse fascia. Striae radiate at the 

 ends, 8 in 0,oi mm. — Nav. int. Lagst. Spetsb. D. 23 PI. I f. 3. 



Fresh water: Spitsbergen (Lagst.), Beeren Eiland (Lagst.), Australia (Blue Mountains)! 

 This form seems, according to Lagbrstedt, to graduate into P. horealis and P. Brebissonii. 



23. P. Balf'onriana Grun. Ms. — V. elliptical. L. 0,oo8 to 0,oi; B. 0,oo4 mm. Area wide. 

 Striae distant, 10 in 0,oi mm. — PI. I f. 18. 



Fresh water: Scotland (Grun.), North Iceland! 



24. P. borealis Ehb. (1843). — V. linear-elliptical, with rounded or subtruncate ends. L, 

 0,03 to 0,06; B. 0,007 to 0,oo8 mm. Median line with approximate central pores and hook-shaped 

 terminal fissures. Area narrow Striae parallel, 5 to 6 in 0,o 1 mm. — Am. PI. I: 2 f. 6. Nav. ho- 

 realis KtlTz B. p. 96. Grun. Verb. 1860 p. 518. Lagst. Sp. D. PI. I f. 4. A. S. Atl. PI. XLV 

 f. 15—21. V. H. Syn. p. 76 PI. VI f. 3, 4. Wollb PI. IX f. 23. Pinnul hehridensis Greg. M. J. 

 1854 p. 28 PI. IV f. 13. Pirn, chilensis Rabh. Alg. Sachs. 885 (1859). 



On mosses, moist earth, in fresh water: Spitsbergen! Beeren Eiland (Lagst.), Greenland! 

 Iceland! Sweden! Finland! Germany! England! Belgium (V. H.), Switzerland! Japan! S:t Pauls 

 Island (Grun.), Sandwich Islands! Australia (Blue Mountains)! New Zealand! South Africa! 

 Argentina! Ecuador! W. Ind. S:t Vincent! 



.. , Valve lanceolate P. alpina W. Sm. 



more or less narrow, elliptical . . . ,2. 



n J Very small forms. L. about 0,oi mm. . , P. Balfouriana GrRUN 



\ Lengtl 



,, f L. 0,1 mm. and more . . P. lata Bb^b. 



