KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 



26. n:o 2. 69 



Forma media: L. 0,o7 to 0,12; B. 0,oi7 to 0,02 mm. Strife IX to 19 in 0,oi mm., composed 

 of puncta, 13 to 18 in 0,oi mm. — Nav. af finis Greg. M. J. 1854 II f. 8. Grun. Verh. 1860 PI. V 

 f. 2. DoNK. B. D. p. 33 PL V f. 8. Nav. firma var. subumpliata Grun. A. S. Atl. XLIX f. 19. 



Fresh water: Greenland! Iceland! Spitsbergen (Lagst.)! England! Sweden! Finland! South 

 Africa! Australia (Murray River)! 



Forma maxima: L. 0,i8 to 0,3; B. 0,o4 mm. Striae 12 to 17 in 0,oi mm. Puncta 14 to 15 

 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 rostrate-capitate ends. L. 0,o6 

 to 0,1; B. 0,02 to 0,025 mm. Strise 17 in 0,oi mm. — Nav. producta W. Sm. B. D. I p. 51 PI. 

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

 var. producta 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. af/inis var. amphirynchus. 



4. N. Obliqiie-Striatum A. S. (1877). — V. linear, slightly triundulate, with cuneate ends. 

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

 tate, puncta 17 to 18 in 0,oi mm. — Nav. obi. 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,i7; 

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

 0,01 mm. — Nav. Iridis Ehb. Am. p. 130 PI. IV: 1, f. 2. KuTZ. 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. XUI 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. Strosb, 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, Delaware)! Cape Horn 

 (Petit). Australia (Blue Mountains)! 



Var. ampliata Ehb. (1842). — V. narrow, elliptical, with broad, subrostrate ends. L. 0,o7 

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

 p. 337 M. Geol. A. S. Atl. XLIX f. 4, 5. Nav. affinis W. Sm. B. D. XVI f. 143. Strosb, 

 Kliecken D. £ 12. 



Fresh water: Sweden, Degernas (AtL); Holstein (AtL). Houghton, Michigan N. A.! 



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

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

 gomphus Ehb. Am. 11 f. 27, IIL 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. Verb. 

 1860 p. 544 PL V f. 2. Nav. dilatata A. S. AtL XLIX f. 9. Nav. Iridis var. amphigomphus 

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



Freshwater: Greenland! Spitsbergen (Lagst.)! 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,o5 5 to 

 0,1; B. 0,015 mm. Strise 20, puncta 20 in 0,oi mm. — Nav. Hitch. Ehb. Am. p. 130, M. G. V: 3 

 f. 11. Done. B. D. p. 29 PL V f 4. A. S. AtL XLIX f. 35, 36. 



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

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



N. Hitchcockii may be regarded as a undulate form of N. amphigomphus. 



