2 14 



F. nohiUs Ehrb. 

 Ehrb. Berl. Ak. 1840. p. 214. A. Schm. Atlas pl. 43, f. 1. 



Rare: Stene r; the Østnesfiord r. 



Dktribution: Fresh water species, especially frequent in 

 Northern and Western Europe. 



b. Divergentes Cl. 1. c. p. 77. 



F. l('i/ume)i Ehrb. 

 Ehrb. Mikrogeol. pl. II, a, f. 12. Xavimla I. A. Schm. Atlas pl. 44, figs. 44—47- 



Very rare: The Østnesfiord, r. 



DistriJnttion: Fresh water .species, frequent especially in 

 Northern and Western Europe. Africa. Asia. Australia. America. 



F. diveryens W. Sm. 

 W. Sm. Blir. Diat. I, p. .^7, pi. 18, f. 177. Navicula d. A. Scum. Atlas pi. 44, f. 9. 



Very rare: The Østnesfiord, r. 



Distribution: Fresh water species, frequent especially in 

 Northern and Western Europe. Asia. Australia. America. 



c. Distantes Ci.. 1. c p. 80. 



P. lata (Bréb.) W. Sm. 



W. Sm. Brit. Diat. I, pi. 18, f. lt)7. FrustuUa lata Bréb. Cons. p. 18. 



Frequent: Svolvær r, Raftsund r, the Østnesfiord r, Stene + c. 

 Distribution: Fresh water species. Arctic regions. Western 

 Europe. Switzerland. Australia. 



F. borealis Ehrb. 

 Ekre. Am. pl. I, 2. C. ti Xaricnla b. A. Schm. Atlas iil. 45, figs. 1.5—21. 

 Very rare: Stamsund, r r. 



Distribution: Frequent fresh water species, especially in arctic 

 and alpine regions: Northern and Western Europe; Switzerland. 

 Asia. Africa, America and Australia. 



d. Marinæ Cl. 1. c. p. 94. 



P. quadratarea (A. Schm.) Cl. 



A. Schm. Nords. Diat. p. 90, pi. II, f. 26. Xavicida phumlaria Cl. Svensk. N. 



Dint. |,. 224, pi. IV, figs. 1—2 (earlier name). 



Frequent : Stamsund -f-, Svolvær r, the Østnesfiord r, Stene 

 r +, Gaukværø -f- c. 



Distribution: Coasts of the North Sea. Arctic regions, frequent- 

 The Mediterranean. Australia. 



P. claviculus «iRKG.) Cl. 



Cl. I, c. ]!. 9(i. Xarinila e. Grrg. Diat. of Clyde, p. 478, pi. IX, f. 5. A. Schm. 



Kords. Diat. pi. II, f. 28. 



Rare: Stamsund r -f, Gaukva^rø r. 



Distribution: (\)a.sts of the North Sea. Sweden. Balearic 

 Islands. 



Distribution: Coasts of the North Sea. Florida. Japan. 



]>ipIoiieir4 El 



Cl. Synops. Navic. Diat. I, p. 



Do.NK. Micr. Journ. (n 



P. cruciformis Donk. 

 I, 11. 10, id. I, f. 7. A. Scum. Nords. Diat. 



I, f. 2.") 



Rare: Stamsuii<l r, Svolvær r, (Jaukvieru r. 

 Distrihulion: Coasts of the North Sea. Finmark. Baltic. 

 West Indies. Cape Horn. Seychelles. 



P. TrcTfJynna (Donk.) Rahenu. 



Rabbnh. F1. Eur. Algar I, |i. 210. y,jri<ulii 'J'. Donk. Mier. -lonrn. 1, 1861, 



l'- ^' pl- ': ''■ -■ 



Rare: Stamsund r, Svolvær r, Stene r. 



The material examined was especially rich in forms of this 

 beautiful genus. For the sake of greater clearness, they are arranged 

 in the two groups Didymæ and EUiptieæ, although these groups 

 by some intermediate forms pass into each other. 



a. Ellipticae V. H. Synop-. 



D. hyalina (Done.) Cl. 



Cl. 1. e. p. 80. Xavictda h. Doxk. Micr. Journ. I, p. 10, pi. I. f. ti. A. Schm. 



Atlas pi. 70, figs. 1 — ,0. 



Very rare: Stamsund, r. 



Distribution: Coasts of the North Sea. Finmark. 



D. coffeæforinis (A. Schm.) Cl 

 Cl. I. c. p. 81. Nariada c. A. Schm. Nords. Diat. p. 88, pi. I, f. 22: pi. II, f. 1.3. 



Perhaps a variety of the following species. 

 Rare: Stamsund, r -|-. 



Distribution: Coasts of the North Sea. Naples. Macassar 

 Straits. 



D, siiborbicularis (Gkei;.) Cl. 

 Cl. 1. e. p. 81. yavkida Smithii var. s. Greg. Diat. of Clyde p. 487, pi. IX, f. 17. 



Somewhat rare: Stamsund +, Svolvær r. 

 F)istril)ution : Coasts of the North Sea. Davis' Strait. The 

 Mediterranean. Caspian Sea. Indian Ocean. America. 



D. eudoxia (X. Schm.) 



Navkula e. A. Scum. Atlas pi. VIII, f. 40, (il. 70. f. 71. .V. uiedifen-aiira 



A. Schm. Nords. Diat., id. II, f. 10, non Klttz. D. rontiijua rar. etidoæia ('i.. 



1. c. p. 83. 



TIlis beautiful species is so easily recognizable and seems 

 to be so well distinguished from the following that I prefer to keep 

 them separate instead of referring both to D. roiitiijuu. as Cl. 

 (1. c. p. 82) does. 



Rare: Stamsund r^ , Raftsund r. 



Distribution: West coast of Norway. Tlie Mediterranean. 

 Red Sea. Indian Ocean. Galapa.u'os Islands. 



D. sejuncta (A. Schm). 

 Xaricida .s. A. Schm. Nords. Diat. p. 87, pi. I, f. 18. X. eugenia A. Schm 

 Atlas pi. 8, figs. 44—4.5. Diploids contiyua (A. Schm.) rar eugenia Cl. 1. c. p. 83. 



TIlis species is certainly a Dijiloiu-is. not a ('iiloueis as Cl. 

 1. c. supposes. A. Schm. (Noi'ds.) compares it with D. nitcscens and 

 mentions it (N. eugenia) another time (Atlas 1. c) as a connecting 

 link between D. nitescens and D. eudoxia. 



Horns of the central nodule not plainly separated. Now and 

 then, till' division line is, however, seen. Costæ apparently lineate; 

 the very faint longitudinal lines form a, single row of alveoli bet- 

 ween the costæ. Sometimes tlie valves arc a little constricted in 

 the middle. 



I (-an find no essential dift'erence between this form and .V. 

 rugciiiu. The cost;e in the latter are stated to be 8 — 9 on K) n, 

 in the IVtrmer 12. The structure of D. sejuncta is, however, some- 

 what variable, and answers perhaps best to 10 costæ on 10 |i 



