KONGL. SV. VET. AKADEMIENS HANDLINGAK. RAM) 27. Nto 3. 88 



Var. semicruciata Vh. — Stria- in tlic middle unilHtcrally intrfniptfd. — Nav. f/ihha ft 

 Peclm (tRUN. Verb. l«(i() p. h\l PI. IV f. 17. 



Fre.sli water: Sweden (Ojasjo, Blekiiige)! Norway (Stavanger Dept.)I America (Canada West., 

 Waltham Mass., Caldas Brazil)! 



Var. intcrrupta Cl. — Strife interrupted on both sides of the central nodule. — Nav. Stnn- 

 roptera (tRUN. Verh. 1«60 p. oU^ PI. IV f. IH (f. gracilis) f. 11) (f. parva) Fr. Jos. Land D. PI. 1 f. 18. 



A. S. Atl. XLIV f. 41. V. H. Syn. p. 77 PL VI f. 7, f. (J (f. parva). Nav. Tuhellaria V. H. Syn. 

 f. «. Nav. abaujcnsi.s Pant. II p. 41 PI. Ill f. 54 (18«1)). 



Fresh water: Franz Josefs Land (Grrun.), Sweden! Finland! Norway! Scotland! France 

 (Lac Gerardmer Vosges)! New Zealand! Hawaii! Demerara! Surinam! North America (Waltham 

 Mass., Troy, New Hampshire)! Ecuador! 



Var. sancta Grun. Ms. — V. strongly gibbous in the middle. L. 0,ii; B. (),oi.5 mm. Area 

 very wide. Stripe 10 to 11 in 0,01 mm. 



Fresh water: Santos, Brazil! Bengal! 



81. P. raiigoonensis Grun. Ms. — V. linear, with broad, rounded ends. L. 0,o7 to 0,io; 



B. 0,012 to 0,0 14 mm. Median line filiform, with approximate central pores and comma-like, ter- 

 minal fissures. Axial area distinct, but narrow, in the middle dilated to an elliptical space, or on 

 one or both sides, to a transverse fascia. Striae 8 to 10 in 0,oi mm. divergent m the middle, con- 

 vergent at the ends. — Stauroptera semicruciata Ehb. M. G. XXXIII: 2 f. 7*? 



Fresh water: Rangoon! 



This form is scarcely specifically distinct from P. stauroptera. The same is also the case 

 with Nav. Troyana Grun. (in Cl. and Moller Diat. N:o 275) and Nav. Forarmcnsis Grun. (Cl. and 

 Moller Diat. N:o 140), which I am unable to distinguish from P. rangoonensis. The only diffe- 

 rences between these forms and P. stauroptera consist in the shape of the valve and in the term- 

 inal fissures, M^hich are more curved in P. rangoonensis. I hav efound such forms from the following 

 localities: Greenland, Sweden (Forarm, Smaland), Troy (New Hampshire), Demerara Kiver, New 

 Zealand, Blue Mountains (Australia). 



82. P. Brandelii Cl. (1891). — V. linear gibbous in the middle and at the ends, often 

 with tri-undulate margins. Ends broadly rounded, frequently subclavate. L. 0,o7 to 0,o8 ; 

 B. 0,007 to 0,009 mm. Median line filiform, with semicircular terminal fissures. Area distinct, 

 narrow, linear, in the middle widened to a broad transverse fascia, having a linear marking on 

 each side of the central nodule. Strise 14 in 0,oi mm., divergent in the middle, convergent at 

 the ends. - D. of Finl. p. -li] PL 1 f. 8, 9. 



Fresh water: Sweden (Almten in Kalmar Ian)! Finland! France (Lac Gerardmer, Vosges)! 



83. P. stomatophora Grun. (187(i). — V. linear-lanceolate, gradually tapering from the 

 middle to the rounded ends. L. 0,o7 to 0, 11; B. 0,09 to 0,011 mm. Median line with bayonet- 

 shaped terminal fissures. Axial area narrow, linear, widened in the middle to a narrow trans- 

 verse fascia, where is on each side of the central nodule a linear marking. StriiP 12 to 13 in 

 0,01 mm., strongly divergent in the middle and convergent at the ends. — Nav. stotnato2>hora 

 Grun. in A. S. Atl. XLIV f. 27 to 29. 



Fresh water: Iceland, Scotland (Island of Lewis)! Norway (Dovre, Atl.)! Sweden (Ross- 

 langen in Kalmar Ian)! Finland! Germany (Harz, Atl.), New Zealand! America (Canada, Crane 

 Pond, French Pond)! 



Var. continua Cl. — L. 0,o7 to 0,12; B. O.oog to 0,oi4 mm. Striffi 18 in 0,oi mm., not 

 interrupted. 



Fresh water: Loch Kinnord, Scotland! Sweden (Lake Rosslangen in Kalmar Ian)! 



84. P. bogotensis Grun. (1876). — V. linear, with rounded ends. L. O.i to 0,n; B. 0,oi3 

 mm. Median line with approximate central pores and bayonet-shaped terminal fissures. Axial 



