KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 93 



Fresh water: Sweden (Lapland to Småland)! Norway (Stavanger Dept.)! Finland! Eng- 

 land! Scotland! Ireland! France! Switzerland (Br.), Italy (Livorno, foss.)! America (Salem and 

 Boxford Mass., Big Lake Cal. Montgommery Ala., Washington Terr. all foss.)! 



Var. neogena Grun. (1882). — L. 0,2 is; B. 0,032 to 0,036 mm. Area broader. Stria 5 in 

 0,01 mm. — Nav. nob. var. neog. Grun. Foss. Diat. Öster. Ung. p. 143 Pl. XXX f. 41. Pant. III 

 Pl. IX f. 159. 



Fresh water: Dubravica, Hungary, foss. (Grun.). 



Var. fossilis Pant. (1889). — L. 0,i2 to 0,2i; B. 0,oi8 to 0,033 mm. Strise 6,5 to 8 inO,oi 

 mm. — Pant. II p. 51. 



Fresh water?: Bory Hungary (Pant.). 



65. P. ilexuosa Cl. N. Sp. — V. linear to elliptic-linear, with rounded ends. L. 0,22 to 

 0,27; B. 0,04 to 0,04 8 mm. Median line complex. Central nodule large, excentric; terminal fissures 

 comraa-shaped. Axial area broad, somewhat less than V3 of the breadth of the valve, not, or very 

 slightly, widened in the middle. StricE 4,5 to 5 in 0, 01 mm., slightly divergent in the middle and 

 convergent at the ends, crossed by broad, distinct bands. — Pl. I f. 23. 



Fresh water: Canada (Eralton Lake)! United State (Cherryfield, Crane Pond)! 

 This form is nearly akin to P. nohilis, but closely resembles P. Dactylus, from which species 

 it differs principally by its complex median line. 



66. P. streptoraphe Cl. (1891). — V. linear with parallel margins and broad, rounded ex- 

 tremities. L. O, i8 to 0,2 6; B. 0,03 mm. Median line strongly complex; terminal fissures comma- 

 shaped. Axial area moderately narrow, less than Vs of the valve, not widened in the middle. 

 Stria; almost parallel, 5 in 0,0 1 mm., crossed by a broad and distinct band. — Nav. sp. A. S. Atl. 

 XLII f. 7. Nav. viridis var. sublinearis Grun. Franz Jos. L. D. p. 98 Pl. I f. 22. Pin. streptoraphe 

 Cl. Diat. of Finl. p. 23. 



Fresh water: Franz Jos. Land (Grun.), Sweden (common in most diatomaceous earths from 

 Lapland to Småland)! Finland! England (Premnay Peat, Loch Leven)! France (Lac de Grandlieu 

 Loire infér.)! N. America (common in most diatomaceous earths, for inst. Nova Scotia, New York, 

 Massachusetts, Calif ornia) ! 



Var. styliforniis Grun. (1884). — L. 0,ii6; B. 0,oi25 mm. Strite 7 in 0,oi mm. Area narrow. 

 — Ehb. M. g. XXXVIII: n f. 6? Nav. viridis var. stylif. Grun. Franz Jos. L. D. p. 98 Pl. I f. 21. 



Fresh water: Franz Josefs Land (Grun.). 



Var. minor Cl. (1891). — L. 0,o85 to 0,i; B. 0,oi5 to 0,oi6 mm. Area distinct. Strise 

 slightly radiate, 6,5 in 0,oi mm., interrupted on one or both sides of the central nodule. — Nav. 

 viridis A. S. Atl. XLII f. 20. Pinnul. viridis var. minor Cl. Diat. of Finl. p. 22 Pl. I f. 2. 



Fresh water: Sweden (Rosslängen Små!., Ebbetorp Dept. Smal.)! Finland! 



67. P. isostaiiron (Ehb. 1843?) Grun. (1880). — V. linear, with parallel margins and 

 rounded ends. L. 0,03 to 0,o7; B. 0,oo8. Median line flexuose, axial area narrow, widened around 

 the central nodule to a transverse fascia. Strise parallel 9 to 12 in 0,oi mm. — Sfauroptera iso- 

 stauron Ehb. Am. p. 135 f. 1. M. G. XVI: i f. 7? Nav. viridis var. icostauron Grun. A. D. p. 27 

 Pl. I f. 14. Nav. icostauron var. conifera Brun a. Hérib. D. d'Auvergne p. 91 Pl. Il f 2. 



Fresh water: Greenland! Iceland! Kära Sea (Grun.), Sweden (Förarm in Asnen, Upsala)! 

 Finland! Puy du Dome (fossil), Colorado (Brun CoU.)! 



Stauroptera isostauron of Ehrbnberg is very doubtful and may perhaps denote some forms 

 of Pinn. divergens, scarcely the species of Grunow, which is -closely related to P. Aestnarii Cl. 

 P. isostauron may perhaps more properly be placed in the group Gracillinice. 



68. P. Aestnarii Cl. N. Sp. — V. linear, with parallel margins and rounded ends. L. 0,io 

 to 0,12; B. 0,0 16 mm. Median line flexuose; terminal fissures semicircular. Axial area moderately 



