KONGL. SV. VET. AKADEMIENS HANDLINGAK. BAND 27. N:() 3. 85 



longer and shorter, very convergent at the ends. — Am. p. 133. M. (t. 11: 2 f. 13. Nnv. Sill. 

 Lewis Proceed. Acad. Nat. Scienc. Philad. PI. 11 f. 8. Walker a. Chase N. a. R. 1). PI. II p. 6 

 PI. 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. 0,019 ram. Terminal nodules hook-shaped. Axial area uniting with the central 

 area in a lanceolate .space. Stritc 13 in O.oi mm., slightly radiate, at the ends convergent. — 

 PL I f. 15. 



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



Nac. fransi/lvanica Pant. (Ill PI. I f. 7) and its var. prodiicta (1. c. PL XXIll 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,oo6.t; B. 0,017 to 0,02 mm. Terminal fissures small and indistinct. Axial and central 

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

 near the ends. — Nav. Thorax Brun D. especes n. p. 41 PL XVI f. 6. 



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



VI. Brevistriatse. 



Artificial key. 

 Margins of the valve undulate N. nodosa Ehb. 



not — 2 



( 



I Area punctate I\[. acrosphwria Bnis 



I 

 { 



not — 3. 



„ , Ends cuneate 4. 



not — 5. 



. J Median line straight P. singularis A. S. 



— — tlexnose P. integra Grun. 



j 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,oi ram 8. 



— 14 to 15 — — P. paiilensis Grun. 



6. i^"^ 



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



\ L. 0,05 to 0,08 mm P. heniiptera KtJTz. 



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

 subcuneate ends. L. O.ob to 0,o8; B. 0,012 to 0,oi.3 mm. Axial area generally wide, more or less 

 lanceolate. Terminal fissures semicircular. Stritc 8 to 10 in 0,oi ram. slightly radiate or almost 

 parallel. — Nav. hem. KtJTz 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. Sav. instabilis A. S. Atl. XLIII f. 35 to 40. Nav. dc- 

 hilis Pant. II p. 44 PL XII f. 214 (1889). Nav. hrjhricla Hi^rib. a. Perag. D. d'Auvergne p. 85 

 PL IV L 9 (1893). Nav. ktjhrida var. Biclutvshii H^rib. a. Perag. 1. c. p. 85 PL IV f. 10. 



Fresh water: Sweden (Lapland to Skane)! Finland (Russian Lapland to Abo)! Norway! 

 Iceland! Great Britain (Premnay Peat, Loch Kinnord)! Italy (S:ta Flora IJept.)! 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.)! 



