KONGL. SV. VKT. AKADEMIKNS HANDLINGAH. BAND 27, N:() 3. 28 



alternately longer and shorter. — Finn. Gastrum Ehb. Am. Ill: 7 f. 23. M. (1. V: 1 f. 12. StrOse 

 Klieken D. f. 1 h. N. Gastrum Donk. B. D. p. 22 PI. Ill f. 10. Grun. A. D. p. 31. V. H. Syn. 

 p. 87 PI. VIII f. 25, 27. Pant. Ill PL III f. 48. Nat: exif/ua Pant. Ill PI. Ill f. 4.t (1893). 

 N. varians Greg. T. M. S. Ill p. 10 PL II f. 27, 28 (1855). N. Hoffmannii Pant. II p. 47 

 PL XIV f. 245 (1889)? 



Fresh water: Sweden! Finland! England! Ireland! Belgium (V. H.), Sea of Kara! Cape 

 DeschnefF! New Zealand! Illinois! 



Var. Jenisseyensis Grun. (1880). — Lanceolate. L. 0,o.38 to 0,o65; B. 0,011 to 0,(n7 mm. 

 Strife about 9 in 0,oi mm. more distant in the middle, where there are only a few shorter ones 

 among the longer, very finely lineate. — A. D. p. 31 PL I f. 28. N. Basilica [Pant. Ill 

 PL VIII f. 129 (1893)? 



Fresh or brackish water: Jenissey (Grun.), Cape DeschneiF! New Zealand! New Caledonia 

 (Kinker Coll.)! 



Var. lafiuscula Grun. (1880). — V. lanceolate. L. 0,024 to 0,o6; B. 0,012 to 0,oi7 mm. 

 Striae 10 to 11 in 0,oi mm. The median strife not alternately longer and shorter. — A. L). p. 31. 

 Strose Klieken D. f. 1 a. 



Fresh and slightly brackish water: Sea of Kara! Sweden (Upsala, Ronneby, Kalmar, fossil)! 

 Finland! East Cape, East Siberia! Cuxhaven (Grun.), Oberrohe and Klieken, fo.ssil! 



Var. exigna Greg. (1854). — V. lanceolate with subrostrate or subcapitate ends. L. 0,oi7 

 to 0,03; B. 0,009 to 0,012 mm. Striffi 12 to 14 in 0,oi mm — Pinnul. exigua Greg. M. J. p. 99 

 PL IV f. 14. N. Gastr. v. exigua Grun. A. D. p. 31. V. H. Syn. PL VIII f. 32. 



Fresh or brackish water: fiulf of Bothnia (Tornea! Pitea!) Finland, Lake Lojo, Abo! Hun- 

 gary, fossil (Grun.), New Zealand! 



Var. horyana Pant. (1889). — V. capitate. L. 0,04 6 to 0,o6; B. 0,oi7 to 0,0 2 mm. Striae 

 7,5 to 8,5 in 0,01 mm. radiate, coarsely punctate, puncta 17 to 18 in 0,oi mm. Median striae 

 alternately longer and shorter. — Pant. II p. 46. 



Marine: Himgary, fossil (Pant.). 



30. N. Placentula Ehb. (1843). — V. elliptic-lanceolate, with rostrate, obtuse ends. L. 0,o5 

 to 0,06; B. 0,016 to 0,028 mm. Axial area narrow, but distinct. Central area irregular, trans- 

 verse. Striae fi to 9 in 0,oi mm., radiate throughout, coarsely lineate or punctate, shortened in 

 the middle, but not alternately longer and shorter. — Finnitl. Flac. EuB. Am. Ill: 7 f. 22. M. G. 

 XII f. 19. Grun. A. D. p. 34 PL II f. 36. N. pusilla Donk. B. J), p. 20 PL III f. 6 h? N. Gastrum 

 V. Flac. V. H. Syn. p. 87 PL VIII f. 26, 28. N. Gastrtwi f. minor. Grun. F. D. Ost. Ung. XXX f. 51. 



Fresh water: Cassel »Polierschiefer ' (Ehb.), Ireland Antrim Co.! Jenissey! New Zealand! 

 California! Oregon! Puerto Monte! Ecuador! 



Var, lanceolata Grun. (1860). — V. broadly lanceolate. Ends not rostrate. L. 0,04; B. 0,oi6 

 mm. Striae 7 to 8 in 0,oi mm. — N. tumida var. lanceolata Grun. Verb. 1860 p. 537 PL IV f. 44. 

 A. D. p. 34. 



Brackish water: Sea of Kara! Skienitz See near Berlin (Grun.), Neusiedlersee (Grun.). 



Nav. Flacentula is very nearly akin to Nav. Gastrum, and it is questionable whether they 

 should not be united in one species. The median striae are in Nav. Gastrum, but not in Nar. Flacen- 

 tula, alternately longer and shorter, but this characteristic is subject to great variation, the var. 

 Jenisseyensis having onlj' a few, and the var. latiuscula no, shorter median striae. Of more im- 

 portance is it that Nav. Flacent'da has coarsely lineate, or almost punctate striae. Nav. anglica 

 is nearly akin to Nav. Gastrum and might be considered as a variety of it. There exists in fact 

 no limit between these three species; Nav. Flacentula appears to be akin to Nav. leptostigma, 

 which has finer, distinctly punctate, striae and that to Nar. platy stoma, the strife of which ai-e 

 very finely punctate. On the other hand N. Flacentula is by its coarsely punctate striae allied 

 to the section Functatte, among which Nav. amphibola is nearly akin to N'av. Flacentula. Smaller 



