214 



E. Jergense 



P. nobilis Ehrb. 

 Ehkb. Berl. Ak. 1840, p. 214. A. Schm, Atlas pi. 43, f. 1. 



Rare: Stene r; the 0stnesflord r. 



Distribution: Fresh water species, especially frequent in 

 Northern and Western Europe. 



b. Divergentes Cl. 1. e. p. 77. 

 P. legumen Ehrb. 



Ehrb. Mikrogeol. pi. 11. -'. f. 12. Navicula I. A. Schm. Atlas pi. 44, tigs. 44 — 47- 



Very rare: The 0stnesfiord, r. 



Distribution : Fresh water species, frequent especially in 

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



P. direr yen* W. Sm. 

 W. Sm. Biit. Diat. I. p. 57, pi. IS. f. 177. Navicula >t. A. Schm. Atlas pi. 44, f. 9. 



Very rare: The Ostnesfiord, r. 



Distribution : Fresh water species, frequent especially in 

 Northern and Western Europe. Asia. Australia, America. 



c. Distantes Cl. 1. c. p. 80. 



P. lata (Breb.) W. Sm. 



W. Sm. Brit. Diat. I, pi. 18, f. 167. Frnstatia lata Breb. Cons. p. L8. 



Frequent: Svolvaer r. Raftsund r. the 0stnesfiord r, Stene + c. 

 Distribution: Fresh water species. Arctic regions. Western 

 Europe. Switzerland. Australia. 



P. borealis Emir,. 



Ehrb. Am. pi. I, i, f. 6. Navicula b. A. Schm. Atlas pi. 4.Y liu-. 15—21. 



Very rare: Stamsund, rr. 



Distribution: Frequent fresh water species, especially in arctic 

 and alpine regions : Northern and Western Europe; Switzerland. 

 Asia. Africa, America and Australia, 



d. Marina* Cl. 1. c.p. 94. 



P. quadratarea (A. Schm.) Cl. 



A. Schm. Novels, Diat. p. 90. pi. II. f. 26. Navicula pinmilaria Cl. Svensk. N. 



Diat. p. 224. pi. IV. figs. 1—2 (earlier name). 



Frequent: Stamsund +. Svolvaer r, the Ostnestiord r, Stene 

 r +• Gaukva?ro 4- c, 



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

 The Mediterranean. Australia. 



P. claviculus (Greg.) Cl. 



Cl. 1. c. p. 96. Navicula c. Greg. Diat. of Civile, p. 478, pi. IX, f. 5. A. Schm. 



Nords. Diat, pi. II, f. 28. 



Rare: Stamsund r -f-. Gaukvsero r. 



Distribution: Coasts of the North Sea. Sweden. Balearic 

 Islands. 



P. cruciforiuis Donk. 

 Donk. Micr. Journ. in. s.i l. p. 10. pi. I, f. 7. A. Schm. Nords. Diat. pi. II, t. 25 



Rare: Stamsund r. Svolvaer r, Gaukvsero r. 

 Distribution : Coasts of the North Sea. Finmark. Baltic, 

 West Indies. Cape Horn. Seychelles. 



P. Trevelrana (Donk.) Babenii. 

 Rabenh. Fl. Eur. Algar I, p. 210. Navicula T. Donk. Micr. Journ. I, 1861, 



p. 8, pi. I, f. 2. 



Rare: Stamsund r, Svolvaer r, Stene r. 



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



Diplomas Ehrb., Cl. Synops. Navic. Diat. I, p. 76. 



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 Didymae and Ellipticse, although these groups 

 by some intermediate forms pass into each other. 



a. Ellipticse V. H. Synops. 



D. hyalina (Donk.) Cl. 

 Cl. 1. <•. p. 80. Navicula h. Donk. Micr. Journ. I, p. 10, pi. I, f. 6. A. Schm. 



Atlas pi. 70, figs. 1 — 5. 



Very rare: Stamsund, r. 



Distribution: Coasts of the North Sea. Finmark. 



D. coffeseforwis (A. Schm.) Cl. 

 Cl. 1. c. p. 81. Navicula c. A. Schm. Nords. Diat. p. 88, pi. I, f. 22; pi. II, f. 13. 



Perhaps a variety of the following species. 

 Rare: Stamsund. r +-. 



Distribution: Coasts of the North Sea. Naples. Macassar 

 Straits. 



D. suborbicularis (Greg.) Cl. 

 Cl. 1. c. p. 81. Navicula Smithii var. s. Greg. Diat. of Clyde p. 4S7, pi. IX. f. 17. 



Somewhat rare: Stamsund -f, Svolvaer r. 

 Distribution: Coasts of the North Sea. Davis' Strait. The 

 Mediterranean. Caspian Sea. Indian Ocean. America. 



D. eudoxia (A. Schm.) 

 Navicula c. A. Scum. Atlas pi. VIU, f. 40, pi. 70. f. 71. N. iiiatitcvvanea 

 A. Schm. Xords. Diat.. pi. II, f. 10, non Kutz. D. enntigua var. eudoxia Cl. 



1. c. p. 83. 



This 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. cemtigua, as Cl. 

 (1. c. p. 82 1 does. 



Rare: Stamsund r -\ , Raftsund r. 



Distribution: West coast of Norway. The Mediterranean. 

 Red Sea, Indian Ocean. Galapagos Islands. 



D. sejuncta (A. Schm.). 

 Navicula s. A. Schm. Nords. Diat. p. S7. pi. I, f. 18. N. eugenia A. Schm_ 

 Atlas pi. 8. figs. 44 — 45. Diploncis contigua(A. Schm.) var eugenia Cl. 1. c. p. 83. 



This species is certainly a Diploneis, not a Caloneis as Cl. 

 1. c. supposes. A. Schm. (Nords.) compares it with D. nitescens and 



mentions it (V. eugenia) another time (Atlas 1. cl as a connecting 

 link between P>. nitescens and D. eudoxia. 



Horns of the central nodule not plainly separated. Now and 

 then, the division line is, however, seen. Costa 3 apparently lineate; 

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

 ween the costa?. Sometimes the valves are a little constricted in 

 the middle. 



I can find no essential difference between this form and N. 

 eugenia. The cost* in the latter are stated to be 8 — 9 on 10 |J., 

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

 what variable, and answers perhaps best to 10 costa> on 10 p. 



