otliiT parts of the v;il\i'. 'I'lic iiirnius air aNd more protracted 

 towards tlie oiuls, and not consiuciimisly (tos.mmI 1i\ transverse costæ 

 at the sides of the central nodiilr. 



Always easy to distiiiLiuisli iVuni tlic incccdini.'- species. 



FrtHincnt: Staiiisund i c, Hrctti'snos Skroven r4-. I^ai't- 

 sund r {-, Sti'iic r -\-. 



Distrihiitiuii: Coasts of the Nortli Sea. Alexandria. Indian 

 Ocean. Pacitic Ocean. Central .America. 



I), didyma (Ehrb.) Euhb. 



EiiRH. Mikiosji-oliijr. |il. 19. f. 32. Piiinularia <l. Ehkii. Kiviileili. \\. I'l. AVirJc- 



uht iJhhjiiia \. SiHM. Noi-its. Di.nt. ij1. I, t'. 7. 



Not nnfrequent: .MosUenstrommen r. Svolva'r r+, the Ost- 

 nestiord r, Kaftsnnd r, iStcne r. 



Distribution: Especially in lirackisli water. Coasts of tiie 

 North Sea. .\rctic regions, lialtic. lilack Sea. Caspian iSea. 

 Indian Ocean. Pacific Ocean. Cape Horn. West Indies. 



D. hotubus Ehrb. 



Ehrb. Mikn>i;eol. jil. U». f. 31. Xavicnla b. Creg. Dial. ..f Clyac, |i. 484, 



pi. IX, f. l->. X. (/CDnm A. Schm. Norfls. ])i;it. pi. I. f. 1; pi. II, f. I. 



Frequent: Moskenstrommcn r -(-, Stamsnnd c, Svolvær +, 

 the Ostnestiord r, Raftsund r, Stene +, (iaukværo r -{-. 



Distribution: Coasts of the North Sea and Western Europe. 

 Finmark. The Mediterranean. Black Sea. Caspian Sea. Indian 

 Ocean. Pacitic Ocean, .\merica. 



D. chersonensis (Grin.) Ci.. 



C'L. 1. <•. 1). 91. Xarkula c. (iRUN. in A. Schm. Atla.s ijl. 12, f. 40: pi. H9, f. 21. 



Xaricuh apis (DosK.) A. Schm. Nords. Diat. pi. I. f. 9. 



Not unfrequent: Stamsund +, Svolvær r, Gaukværo r. 

 Distribution: Coasts of the North Sea. The Mediterranean. 

 Indian C)cean. Pacitic Ocean. West Indies. Florida. 



D. crabro Ehrb. 



Jlikrofreol. pi. 19, fi^'.s. 29 a, b (non c). A. Schm. Nords. Diat. pi. I. figs. 5— 6; 



pi. U, l'. 4. D. crabro rar. multkostata (Grc.n.) Cl. 1. c. p. 102. Xarkula 



multicostata Grdn. Wien Vttrli. 1860, p. 524, pi. Ill, f. 13. 



Rather frequent: Moskenstrømmen r, Stamsund +, the 0.st- 

 nesliord -|-, Raftsund r, Stene r, Gaukværø r +. 



Distribution: Coasts of the North Sea and Western Europe. 

 The Mediterranean. Red Sea. Indian Ocean. Pacitic Ocean. 

 We.st Indies. 



Van Heirck Sv 



i-ar. pandura (Bkeb.) "VH. 

 9, l'. 1. Xaviculi pandura Bri- 

 ^iHM. Nords. Dmt. pi. II. f. 3. 



Peculiar form with tongue-shaped segments. 



Very rare: Gaukværo, r r. 



Distrihution : Coasts of the North Sea and Western Europe. 

 The Mediterranean. Red Sea. Indian Ocean. Pacific Ocean. 

 A merica. 



Frnstalia An. 



F. rhomboides (Ehrb.) De Toxi. 



De To.ni Syll. p. 277. Navicula rhomboides Ehrb. Amer. pl. 3, I, f. 1.5. Van- 



licurckia r. Bréb. Ann. Soc. pliyt. Belg. I, p. 204. V. H. Synops, p. 112, i)l. 17. 



figs. 1—2. 



VciT rare: Svolvær r, Erettesnes— Skroven r. 



histiiliiilion: Fresh watei- sjjccies, rather common. 



St«>iiwiM>i*> iiifoiisi>icua ((iiiKr,.) Cl. 



('I.. Synops. Navir. Diat. I, p. 124. Xarkula ( i. Grko. Dial, of Clyli- p 478 



111. IX, t', ii. X. fistula A. SCH.M. Nords. Dial. pi. II, f. 29. 



Frequent: Moskenstrømmen r, Stamsund r, Gaukværo -f c. 

 Distribution: Coasts of the North Sea. Hohusliln (Sweden). 

 Balearic Islands. .Vrctic regions. 



Tra4-li,> iifiM aspera (Ehrb.) t'l.. 



Cl. Synops. Navic. Dial. I, p. 191. Stauroptern a. Ehrb. Anier. pi. I, fi^'s. 1—2; 



Mikrogeol. pi. .3.5 A. XXIII. f. 13. Xarimla a. Van Heurck Synops, pl. X. f. 13 



(rar. yenuina Cl,). 



Common: Moskenstronnnen r, Stamsund -f c, Svolvær -f-, 

 the Ostnesliord c, i\aftsund i' -f, Stene c, (iaiikværo -|-. 

 Distributioi : Cosmopolitan. 



!Tliisto;;'l4»ia I'hw, 



M. exigna Lewis. 



Lewis Prop, Ac. Nat, Sc. Philad, 18H1 p. 65, pl. II, f. 5. Van Helrck Synops. 



p. 70, pl. 4, fiss. 25—26. 



Very rare: Svolvær, r. 



Distribution: B.rackish and marine: Baltic. Belgium. Atlantic 

 coast of America. Behrino' Island. 



M. Smithii Tnw, 



W, Sm, Brit, Diat, II, p, 65, pl, 54, f. ,341, Van Hecrck Synops, p. 70, 



pl. 4. f. 1:3. 



Very rare: Svolvær, i'. 



Distribution: In brackish water. Baltic. England. Saxony. 

 Caspian Sea. Australia. 



M. apicnlata W. Sm. 



W. Sm. Brit. Diat. II, p. 65. \,\. 62, f, :J87, A, ScBM, Atlas pl, 18,5, f, 43; 

 pl, 186, f, 23, 



Very rare: Svolvær, r. 



Distribution: Coasts of the North Sea and Western Europe. 

 The Mediten-anean. Black Sea. China. 



17. Cymhelleæ. 



Cymbella Ag. 



C. cistula (He-mph.) Kirchx. 

 Van Hedrck Synops, p. 64, pi. 2. fi^s. 12—13. 



Very rare: Brettesnes— Skroven, r. 



Distribution: Fresh water species, frequent in arctic, northern 

 or alpine localities. Also in slightly brackish water. 



C', cymbiformis (Ag.?) V. H. 

 Van Heuhck Synops, p. 63, pi. II, figs. 11 a— c. 



Very rare: Stamsund r, the Ostnestiord r. 



Distribution: Frequent fresh ■water .species, especially from 

 Northern and Western Europe. Arctic regions Asia, Africa, 

 America and Australia. 



28 



