KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 85 



longer and shorter, very convergent at the ends. — Aiii. p. 133. M. Gr. Il: 2 f. 13. Nav. Sill. 

 Levvis Proceed. Acad. Nat. Scienc. Philad. Pl. II f. 8. Walker a. Chase N. a. R. D. Pl. II p. 6 

 Pl. II f. 2. 



Fresh water: North America, Crane Pond! New Hampshire (Ehb.), Wolfboro (Lewis). 



. 39. P. lignitica Cl. N. Sp. — V. lanceolate, with protracted, broad and rounded ends. 

 L. 0,075; B. 0,0 19 mm. Terminal nodules hook-shaped. Axial area uniting with the central 

 area in a lanceolate space. Striifi 13 in 0, 01 mm., slightly radiate, at the ends convergent. — 

 Pl. I f. 15. 



Eresh water: Japan, lignite (Brun Coll.)! 



Nav. transylvanica Pant. (III Pl. I f. 7) and its var. producta (1. c. Pl. XXIII f. 345) 

 may be akin to this species, if they do not represent a Caloneis allied to C. formosa, which I am 

 unable to decide from the figures. 



40. P. Thorax Brun (1891). — V. lanceolate, with more or less protracted, obtuse ends. 

 L. 0,04 to 0,0065; B. 0,oi7 to 0, 02 mm. Terminal iissures small and indistinct. Axial and central 

 areas uniting in a lanceolate space. Strifs 6 in 0, 01 mm., slightly radiate, convergent, and closer 

 near the ends. — Nav. Thorax Brun D. espéces n. p. 41 Pl. XVI f. 6. 



Fresh water: Japan, lignite (Brun Coll.)! 



VI. Brevistriatse. 



Artificial key. 



^ i Margins of the valve undulate N. nodosa Ehb. 



■ \ — — — not — 2. 



I Area punctate N. acrosphwria Bréb. " 



I — not — 3. 



I Ends cuneate 4. 



3 



' not — 5 



. j Median line straight P. singularis A. S 



\ — — flexuose P. integra Gedn. 



/ Linear lanceolate, tapering from the middle 6. 



\ — narrowed towards the ends 7. 



Striae 10 to 11 in 0,oi mm P. parva Ehb. 



— 21 to 22 — — P. modesta Grun. 



Striae 8 to 10 in 0,01 mm 8. 



— 14 to 15 — — P. paulensis Geun. 



L. 0,1 to 0,12 mm P. brevicostata Cl. 



L. 0,05 to 0,08 mm. . . . " P. hemiptera Kdtz. 



M 



41. P. hemiptera Kutz (1844). — V. elliptic-linear to linear, narrowed towards the often 

 subcuneate ends. L. 0,o5 to 0,o8; B. 0,oi2 to 0,oi3 mm. Axial area generally wide, more or less 

 lanceolate. Terminal iissures semicircular. Strise 8 to 10 in 0,oi mm. slightly radiate or almost 

 parallel. — Nav. hem. Kutz Bac. p. 97 Pl. XXX f. 11. A. S. Atl. XLIII f. 28, XLV f. 9. P. 

 acuminata W. Sm. B. D. XVIII f. 164. Aaz;. instaUlis A. S. Atl. XLIII f. 35 to 40. Nav. de- 

 hilis Pant. II p. 44 Pl. XII f. 214 (1889). Nav. hyhrida Hérib. a. Pbrag. D. dAuvergne p. 85 

 Pl. IV f. 9 (1893). Nav. hyhrida var. Bielaivsldi Hérib. a. Peras. 1. c. p. 85 Pl. IV f. 10. 



Fresh water: Sweden (Lapland to Skåne)! Finland (Hussian Lapland to Åbo)! Norway! 

 Iceland! Great Britain (Premnay Peat, Loch Kinnord)! Italy (S:ta Fiora Dept.)! Hongkong (Atl.), 

 New Zealand! Australia (Blue Mountains) ! America (Waltham Mass., Crane Pond, Demerara River, 

 Brazil, Trinidad)! 



Var. interrupta Cl. — Strise uni- or bilaterally interrupted in the middle by a trans- 

 verse fascia. 



Fresh water: Japan, lignite (Brun Coll.)! 



