KONGL. SV. VKT. AKADEMlENS HANDLlNGAR. HANJ) 26. N:0 2. 161 



vvitli frustnles of the same appearance. Tt seems then probable tliat the fnistules of (J. Ccsatii 

 occur ench>sed in gelatincms tubes. 



3. ('. aiigiistatu W. Sm. (1853). — V. almost symmetrical, witli, usually, slightly tiiundu- 

 late margins and capitate ends. L. (),o3 to <),()r); B. 0,oo8 mm. Median line almost central, straight- 

 its central pores appi'oximate and its terminal fissures in the ends of the valve. Axial area very 

 narrow or indistinct, not ililated in the middle. Striic about 1(J in 0,oi mm., slightly radiate 

 throughout. — N. angustata W. Sm. B. D. I PI. XVII f. \:^(^. C. cequalis A. S. Atl. "iX f. 69. 

 C. (equ. rar. hyhruln Grun. A. S. Atl. LXXI f. 50. Nnric. iuf/qiiiUdera Laost. Spitsb. I), p. 33 

 PI. II f. 10. 



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

 Norway (Dovre)! Sweden (Gellivara, Degernjis, Loka, Ftirarm in Asnen, fossil)! Finland (Imandra 

 to Karelen and Aland)! 



4. ('. Sfhmidtii (tkun. (1875). — V. almo.st symmetrical, broadly linear, with triundulate 

 margins and cuneate ends. L. 0,o26; B. 0,u()y mm. Median line almost central, slightly flexuo.se. 

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

 A. S. Atl. IX f. 48. 



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



5. €. obtiisiiiscula (Kutz. 1844?) (tRun. 1875. — V. .slightly asymmetrical, broad, almost 

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

 Axial area very narrow; central area small and orbicular. Stria* 12 in U,ui mm., slightly radiate. 



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



Fresh water: Steinitz See (Atl.). 



6. C. alpiua (tRUN. (1863). — V. slight!}' asymmetrical, lanceolate, with convex dorsal and 

 ventral margins and slightlj' obtuse ends. L. OjOS.s 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, finel}' transversely lineate. — Grun. Verb. 1863 p. 148 PI. lY f. 19. 

 A. S. Atl. LXXI "f. 44, 45. Brun. Diat. des Alpes p. 62 PI. Til f. 7. 



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



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

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

 The fine lineation of the stria; appears to indicate a relationship to the group Naticulce Uneolatce, 

 but there is no closely allied from in that group. 



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

 from the middle to the obtuse or slightly capitate ends. L. 0,o6 to 0,07; B. 0,007 to 0,09 ram. 

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

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

 very finely lineate. - Cl. D. of Finl. p. 46 PI. II f. 19. 



Fresh water: Russian Lapland! 



8. €. delicatiila Kutz. (1849). — V. narrow, lanceolate, slightly asymmetrical, obtuse. L. 

 0,022 to 0,03; B. 0,005 to 0,006 mm. Stria" 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 PI. Ill f. 6. 



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

 France! Savoy! Geneve! 



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

 and delicate striaj. It is nearly connected with C. Irfvis, which has broader valves and somewhat 

 coarser striai. Intermediate forms exist between both. 



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



