KONGL. SV. VET. AKADEMIKNS llA XDLIXCiAK. JJAM> 26. N:0 2. 69 



Forma media. ■ L. 0,o7 to 0,12; B. 0,017 to 0,02 nun. Sti'i.c 18 to 19 in 0,01 mm., composed 

 of puncta, 13 to 1« in (),oi mm. - Nav. aflinis (tRE(!. M. .1. 1S;")4 11. f. 8. (tHUN. Verli. l^liOlM. V 

 f. 2. DoNK. B. 1). p. ;5;> PI. V f. <S. Nav. finna mr. siihampliata Grun. A. S. Atl. XLIX t. ID. 



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

 Africa! Australia (Murray River)! 



Forma maxima: L. 0,i8 to 0,3; B. 0,04 mm. Strise 12 to 17 in 0,oi mm. Puncta 11 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. 0,06 

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

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

 car. producta V. H. Syn. p. 104 PL XIII f. 3. Nav. affinis V. H. Syn. PI. XIII f. 4. 



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

 This form graduates into N. affinis var. amphirynchus. 



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

 L. 0,068 to 0,13; B. 0,0 15 to 0,022 mm. Sti'ite 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,o;t to 0,17; 

 B. 0,022 to 0,03 mm. Strite slightly oblique, l(i 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. KtJTZ. Bac. p. 92 PI. XXVIII f. 42. 

 DoNK. B. D. p. 30 PI. V f. 6. A. S. Atl. XLIX f. 2. V. H. Syn. XIII f. 1. Nav. firma KtJTz. 

 Bac. p. 92. PI. 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. Strose, Kliecken D. f. 5 a. 



Freshwater: 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. Strict 16, puncta 17 in 0,oi mm. — Nav. ampliata Ehb. Ber. 1842 

 p. 337 M. Getd. A. S. Atl. XLIX f. 4, 5. Nav. affinis W. Sm. B. 1). XVI f. 143. Strose, 

 Kliecken D. f. 12. 



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



6. N. amphigoiiiphus Ehb. (1843). — V. linear, with cuneate ends. L. 0,o'j to 0,15; B. 

 0,022 to 0,04 mm. Stri;c 16 in 0,oi mm. coarsely punctate, puncta 17 in 0,oi mm. — N'uv. amphi- 

 yomphus Ehb. Am. II f. 27, III: 1 f. 8. KiJTZ. 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. ainphirhynchus Grun. Veih. 

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

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



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

 Switzerlaiul ! 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. Strife 20, puncta 20 in 0,oi mm. — Nav. Hitch. Ehb. Am. p. 130, M. G. V: 3 

 f. 11. UoNFC. 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. 



