KONGL. SV, VET. AKADEMJENS HANDLINGAR. BAND 26. N:0 2. 161 



with frustules of the same appearance. It seems then probable that the frustules of C. Cesatii 

 occur enclosed in gelatinous tubes. 



3. C. angustata W. Sm. (1853). — V. almost symmetrical, with, usually, slightly triundu- 

 late margins and capitate ends. L. 0,03 to 0,o.^; B. 0,oo8 mm. Median line almost central, straight- 

 its central pores approximate and its terminal fissures in the ends of the valve. Axial area very 

 narrow or indistinct, not dilated in the middle. Striae about 16 in 0,oi mm., slightly radiate 

 throughout. — K angustata W. Sm. B. D. I PI. XVII f. 156. C. (squalis A. S. Atl. IX f. 69. 

 C. cequ. var. hyhrida Grun. A. 8. Atl. LXXI f. 50. Navic. incBquilatera Lagst. Spitsb. D. p. 33 

 PI. II f. 10. 



Fresh water (alpine and arctic regions) : Greenland ! Spitsbergen ! Scotland, England (W. Sm.), 

 Norway (Dovre)! Sweden (Gellivara, Degernas, Loka, FSrarm in Asnen, fossil)! Finland (Imandra 

 to Karelen and Aland)! 



4. C. Schmidtii Grun. (1875). — V. almost symmetrical, broadly linear, with triundulate 

 margins and cuneate ends. L. O.oae; B. 0,oo9 mm. Median line almost central, slightly flexuose. 

 Axial and central areas indistinct. Strise about 14 in 0,oi mm., slightly radiate. — Grun. in 

 A. S. Atl. IX f. 48. 



Brackish water: Neusiedler See, Hungary (Atl.). 



5. C. obtusiuscula (KCtz. 1844?) Grun. 1875. — V. slightly asymmetrical, broad, almost 

 elliptical, with subrostrate ends. L. 0,027; B. 0,oi2 mm. Median line almost central, straight. 

 Axial area very narrow; central area small and orbicular. Strise 12 in 0,oi mm., slightly radiate. 



— KtJTZ. Bac. p. 79 PI. Ill f. 68. A. S. Atl. IX f. 49. 



Fresh water: Steinitz See (Atl.). 



6. C. alpina Grun. (1863). — V. slightly asymmetrical, lanceolate, with convex dorsal and 

 ventral margins and slightly obtuse ends. L. 0,023 to 0,04; B. 0,oo8 to 0,oi mm. Median line 

 straight, slightly excentric. Axial area very narrow, not dilated in the middle. Striae 5 in 0,oi 

 mm., very slightly radiate, finely transversely lineate. — Grun. Verh. 1863 p. 148 PI. IV f. 19. 

 A. S. Atl. LXXI f. 44, 45. Brun. Diat. des Alpes p. 62 PL III f. 7. 



Fresh water (alpine, regions): Tyrol (Grun.), Switzerland (Brun), Savoy! 



This little species is very characteristic, not nearly akin to any other Cymhella, and di- 

 stinguished by its unusually coarse and lineate striae. It is an habitant of alpine regions only. 

 The fine lineation of the striae appears to indicate a relationship to the group Naviculee lineolatce, 

 but there is no closely allied from in that group. 



7. C. borealis Cl. (1891). — V. slightly asymmetrical, linear-lanceolate, gradually tapering 

 fl"om the middle to the obtuse of slightly capitate ends. L. 0,06 to 0,07; B. 0,oo7 to 0,o9 mm. 

 Median line almost central, straight. Axial area very narrow, slightly or indistinctly dilated in 

 the middle. Striae 10 (middle) to 13 or 14 (ends) in 0,oi mm., very slightly radiate throughout, 

 very finely lineate. — Cl. D. of Finl. p. 46 PL IT f. 19. 



Fresh water: Russian La,pland! 



8. C. delicatula Kutz. (1849). — V. narrow, lanceolate, slightly asymmetrical, obtuse. L. 

 0,022 to 0,03; B. 0,00,5 to 0,006 mm. Striae 18 or 20 (dorsal) to 21 (ventral) in 0,oi mm., delicate. 



- KtJTZ. Sp. Alg. p. 59. A. S. Atl. LXXI f. 54, 55. V. H. Syn. p. 62 PL HI f. 6. 



Fresh water (moist rocks etc.): Norway (Dovre, Brevig)! Sweden (Lapland to Skane)! 

 France! Savoy! Genfeve! 



This species is recognized by its narrow, almost linear, lanceolate valves and by its close 

 and delicate striae. It is nearly connected with C. Icevis, which has broader valves and somewhat 

 coarser striae. Intermediate forms exist between both. 



K. Sv. Vet. Akad Hapdl. Band 26. N:o 2. 21 



