KONGL. SV. VET. AKADEMIEN8 HANDLINGAK. BAND 27. N:0 3. 75 



II. Capitatse. 



Artificial key. 

 ( Valvi 



^ I Valve rostrate . P. microstauron Ehb. 



I — capitate . .... .3. 



„ I Valve with undulated margins . . P. mesolepta Ehb. 



I — not undulated . . .3. 



Valve linear P. interrupta W. Sm. 



M 



lanceolate , ... . . .4. 



, I Capitate ends broad and large P. globiceps Greg. 



I — ends small . ... 5. 



. ( Valve lanceolate ... ... P. Braunii Geun. 



almost linear ....... ... 6. 



16 to 18 in 0,01 mm. ... P. appendiculata Ag. 



12 to 13 in 0,01 mm P. subcapitata Greg. 



. I Valvi 



6. P. appendiculata Ag. (1828). — V. linear, gently tapering from the middle to the 

 slightly rostrate-capitate ends. L. 0,oi8 to 0,036; B. 0,oo4 to 0,oo5 mm. Area very narrow, dila- 

 ted in the middle to a transverse fascia. Striae 16 to 18 in 0,oi mm., slightly radiate in the middle, 

 convergent at the ends. — Frustulia app. Ag. Icon. Alg. Eur. PL I (according to Kiitz). Nav. 

 app. KuTZ Bac. p. 93 PI. lU f. 28. V. H. Syn. p. 79 PL VI f. 18, 20. N. app. v. irrorata Geun. 

 V. H. Syn. PI. VI f. 30, 31. Nav. Naveana Grun. Verh. 1863 p. 149 PL IV f. 24. V. H. Syn. 

 PL VI f. 29. 



Fresh water (moist rocks, mosses etc.): Iceland! Scotland! Sweden (Gothland)! Belgium 

 (V. H.), Brlinn (Grun.), Bengal! Australia (Blue Mountains)! Greenland! New Jersey (Hoboken)! 

 Ecuador ! 



Var. budensis Grun. (1880). — V. gibbous in the middle, with distinctly capitate ends. 

 Strise 20 to 23 in 0,oi mm. — V. H. Syn. PL VI f. 27, 28. 



Hot springs: Buda-Pesth (Grun.), New Zealand! 



P. appendiculata is closely connected with P. subcapitata and P. molaris and the other hand 

 through the var. budensis with P. Braunii. 



7. P. Braunii GRun. (1876). — V. lanceolate, with capitate or subcapitate ends. L. 0,o3 5 

 to 0,0.5; B. 0,009 to 0,008 mm. Axial area narrow, gradually increasing in breadth towards the 

 middle of the valve, where it expands to a large and broad, transverse fascia. Strise 11 to 12 in 

 0,01 mm., divergent in the middle, convergent at the ends. — Nav. Brauniana Grun. in A. S. Atl. 

 XLV f. 77, 78. Nav. Braunii Grun. in V. H. Syn. p. 79 PL VI f. 21. 



Fresh water: Iceland! Sweden (Rosslangen in Kalmar Ian! Loka, Atl.), Finland! Belgium 

 (V. H.), Bengal! Australia (Blue Mountains)! Argentina! Brazil! 



8. P. subcapitata Greg. (1856). — V. linear, with subcapitate to capitate ends. L. 0,o3 to 

 0,05; B. 0,005 to 0,006 mm. Axial area narrow or indistinct. Central area a transverse fascia. 

 Striae 12 to 13, slightly divergent in the middle, convergent at the ends. — M. J. IV p. 9 PL I 

 f. 30. Pin. Hilseana Janisch in Rabb. Alg. Sachs. N:o 953 (1860). Nav. Hilseana A. S. Atl. XLV 

 f. 65. V. H. Syn. p. 77 Suppl. A. f. 11. Nav. subcapitata A. S. Atl. XLIV f. 53, 55. V. H. Syn. 

 p. 78 PL VI f. 22. A. S. Atl. XLV f. 59, 60. 



Fresh water: Spitsbergen! Sweden (Helsingland, Upsala, Marstrand, Gothland)! Finland! 

 Scotland! England! Kiel! Belgium (V. H.), Bengal! Amsterdam Island! Australia (Blue Mountains)! 

 Argentina! Ecuador! Greenland! 



Var. paucistriata Grun. — Striae short, gradually shortened towards the middle, where is 

 a very broad transverse fascia. — V. H. Syn. p. 79 PL VI f. 23. 



