KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 69 



Forma media: L. 0,o7 to 0,12; B. 0,oi7 to 0,02 mm. Stria? bs to 19 iii 0,oi mm., composed 

 of puncta, lo to 18 in 0, 01 mm. — Nav. affinis Greh. M. J. 1854 11 f. 8. Grun. Verh. 18(J0 Pl. V 

 f. 2. DoNK. B. i), p. 33 Pl. V f. 8. Nav. firma var. tmhumpliata Grun. A. S. Atl. XLIX f. 19. 



Fresh water: G-reenlaud ! Iceland! Spitsbergen (Lägst.)! England! Sweden! Finland! South 

 i\.frica! Australia (Mnrray River)! 



Forma maxima: L. 0,i8 to 0,3; B. 0,o4 mm. StriiB 12 to 17 in 0,oi mm. Puncta 14 to 1.5- 

 in 0,01 mm. — A. S. Atl. XLIX f. 1. 



Fresh water: Monticello, (fossil) New York! 



3. N. productum W. Sm. (1853). — V. subelliptical, with roritrate-capitate ends. L. 0,o6 

 to 0,1; B. 0,02 to 0,025 mm. StriiE 17 in 0,oi mm. — Nav. 2rroducfa W. Sm. B. D. I p. 51 Pl. 

 XVII f. 144. A. S. Atl. XLIX f. 37 to 39. Grun. Verh. 1860 p. 543 Pl. IV f. 35. Nav. Iridis 

 rar. prodiida V. H. Syn. p. 104 Pl. XIII f. 3. Nav. affinis V. H. Syn. Pl. XIII f. 4. 



Fresh water: England! Germany! Belgium (V. H.). Bengal! 

 This form graduates into N. affinis var. amphirynchus. 



4. N. obli(iue-striatum A. S. (1877). — V. linear, slightly triundulate, ^yith cuneate ends. 

 L. 0,068 to 0,13; B. 0,015 to 0,022 mm. Strife 14 to 20 in 0, 01 ram. very oblique, coarsely punc- 

 tate, puncta 17 to 18 in 0,oi mm. — Nav. obl. str. A. S. Atl. XLIX f. 41, 42. 



Fresh water: Demerara River! 



5. N. Iridis Ehb. (1843). — V. linear, subelliptical, with rounded ends. L. 0,09 to 0,17; 

 B. 0,022 to 0,03 mm. Strife slightly oblique, 16 to 19 in 0, 01 mm., punctate; puncta 13 to 17 in 

 0,01 mm. — Nav. Iridis Ehb. Am. p. 130 Pl. IV: 1, f. 2. KtJTZ. Bac. p. 92 Pl. XXVIII f. 42. 

 DoNK. B. D. p. 30 Pl. V f. 6. A. S. Atl. XLIX f. 2. V. H. Syn. XHI f. 1. Nav. firma Kutz. 

 Bac. p. 92. Pl. XXI f. 10. W. Sm. B. D. Pl. XVI f. 138. A. S. Atl. XLIX f. 3. Nav. firma 

 var. major Grun. Verh. 1860 p. 543 Pl. V f. 1. Ströse, Kliecken D. f. 5 a. 



Fresh water: Franz Jos. Land (Grun.), Iceland! Sweden! Finland! England! Vosges! Switzer- 

 land (Brun), Belgium (V. H.). North America (French Pond, Monticello, Uelaware)! Cape Horn 

 (Petit). Australia (Blue Mountains)! 



Var. ampliata Ehb. (1842). — V. narrow, elliptical, with broad, subrostrate ends. L. 0, 07 

 to 0,1; B. 0,023 to 0,026 mm. Strife 16, puncta 17 in O.oi mm. — Nav. ampliata Ehb. Ber. 1842 

 p. 337 M. Geol. A. S. Atl. XLIX f. 4, 5. Nav. affmis W. Sm. B. I). XVI f. 143. Ströse, 

 kliecken D. f. 12. 



Fresh water: Sweden, Degernäs (Atl.); Holstein (Atl.). Houghton, Michigan N. A.! 



6. N. ampliigoinplius Ehb. (1843). — V. linear, with cuneate ends. L. 0,o9 to 0,15; B. 

 0,022 to 0,04 mm. Strite 16 in 0, 01 mm. coarsely punctate, puncta 17 in 0, 01 mm. — .Nav. amphi- 

 gomphus Ehb. Am. II f. 27, III: 1 f. 8. Kutz. Bac. p. 93 Pl. XXVIII f. 40, 41. A. S. Atl. XLIX 

 f. 32 to 34. Nav. firma Donk;. B. D. p. 31 Pl. V f. 7. Nav. affinis v. amphirhynchus Grun. Verh. 

 1860 p. 544 Pl. V f. 2. Nav. dilatata A. S. Atl. XLIX f. 9. Nav. Iridis var. ampliiyomphus 

 V. H. Syn. p. 104 Pl. XIII f. 2. 



Fresh water: Greenland! Spitsbergen (Lägst.)! Sweden! Finland! Belgium (V. H.)! Germany! 

 Switzerland! North America (New Providence! Monmouth! Canada! Sierra Nevada!). South 

 America ! 



7. N. Hitchcockii Ehb. (1843). — V. linear, biconstricted, with cuneate ends. L. 0,055 to 

 0,1; B. 0,0 15 mm. Strise 20, puncta 20 in 0,oi mm. — Nav. Hitch. Ehb. Am. p. 130, M. G. V: 3 

 f. 11. DoNK. B. D. p. 29 Pl. V f. 4. A. S. Atl. XLIX f. 35, 36. 



Fresh water: Sweden! Scotland (Donk.)! Bengal! AustraKa (Murray River)! New Zealand! 

 North America (Port Hope! Crane Pond! French Pond!). 



N. Hitchcocldi may be regarded as a undulate form of N. amphiyomphus. 



