208 



E. Jorgensen. 



Pleuroill'iw 01. 1. o. p. 181. 



Marginal loculiferous rim. Upper valve eostate. Between the 

 costse double rows of small pearls. 



P. costata (Greg.) Cl. 1. o. 



Cocconeis c. Greg, in Q. M. J. Ill, 1855, p. 39, pi. 4, f. 10. Van Heueck 



Synops. pi. 30. tigs. 11 — 12. 



Has a broad and well developed loculiferous rim. 

 Rare: Stamsund r. 0stnesfiord r. Stene r. 

 Distribution: Coasts of the North yea. Arctic regions. The 

 Mediterranean. Canada. Auckland. 



P. pinnata (Greg.) 

 Cocconeis p. Greg. Micr. Jouni. VII. p. 79, pi. H. f. 1. Van Hedrck Synops. 



pi. 3n. fig<. ti — 7. 



Lower valve: The raphe tine, straight, stretching- to the ends 

 of the valve, in the middle witli clavate ends, somewhat separated 

 from each other. Axial area not visible, central one very small, 

 roundish. Stria? very faint, not distinctly seen on my specimens. 



There is a marginal rim with rudimentary loculi which are 

 less than half developed, but very well visible, 4 on 10 |x. A 

 distinct hyaline border. This species seems on the whole to be 

 closely related to Pleuroneis costata though undoubtedly a separate 

 species. 



P. hritannica (N.eg.) Cl. 



Cl. I. c. p. 181. Cocconeis b. Kutz. Sp. Alg. p. 890. Van Hecrck Synops. 



pi. 30, figs. 1—2. 



Very rare: Stamsund rr. 



Distribution: England. The Mediterranean. The Barbadoes. 



Khoirosplu'iiia Grun. 



R. curvata (Kutz ) Grun. 



Gron. Alg. Novara p. 8. Gomphonema c. Kutz. 1833. Gomphonema minutis- 



sima Ehrh. Mikrogeologie pi. 35 A, XII, f. 5, non G. minutissima Grev. (earlier 



name, = G. exiguum Kutz.). 



In fresh or brackish water. A coarser form (var. marina 

 Van Heurck Synops. pi. 26, f. 4) marine. 

 Very rare: Svolvser r, 0stnesflord r. 

 Distribution: Cosmopolitan in fresh and brackish water. 



15. Gomphonemese. 



4 > <> 111 1> 1 - id . 1 As. 



G. constrictum Ehrb. 

 Ehkb. Abh. Berl. Ak. 1830. Van Heurck Synops. p. 123, pi. 23, f. 6. 



Very rare: Svolvser r. 



Distribution: Common fresh water species. 



G. exiguum Kutz. 

 Kutz. Bacill. p. 84, pi. 30, f. 58. 



var. pachyclada (Bred.) VH. Synops. pi. 25, figs. 31 — 32. 

 Gomphonema p. Breb. Consid. p. 21. 



Very rare: Stene rr. 



Distribution: West coast of France. Arctic regions. 



G. kauitschaticum Grun. 

 Grun. Casp. Sea Alg. p. 12. Van Heurck Synops. 25, f. 29. 



Very rare: Svolvser, rr. Valve 45 x 8 |j., narrow, clavate, 

 with rounded broader end. Axial area narrow, dilated to an oblong 

 central area. Striae little radiating, coarser outside the central 

 area, about 15 on 10 \>-, in the middle only 11. 



Distribution : (Marine). Arctic America and Asia. Iceland. 



16. Naviciileze. 



Auricula complexa (Greg.) De T. 



De Toni Syll. p. 347. Amphipora complexa Greg. Diat. of Clyde p. 508, 



pi. XII, f. 62, Van Hecrck Trait.'- d. Diat. p. 2H7, pi. 29, f. 807. 



Probably derived from the plankton. 

 Very rare: Ostnesfiord r. 

 Distribution: Cf. above p. 108. 



Ti-opidont'is Cl. 



T. maxima (Greg.) Cl. 



Cl. Synops. Navic. Diat. I, p. 2ii. Amphiprora in. Greg. Diat. of Clyde p. 507 



pi. XII, f. til. Van Heurck Synops. p. 120, pi. 22, figs. 4—5. 



Somewhat rare: Stamsund r, Svolvser r, the Ostnesfiord r, 

 Stene r +, Gaukvsero r. 



Distribution: Coasts of the North Sea and Ireland. The 

 Mediterranean. Finmark (var. dubia Cl. et Grun.). Indian 

 Ocean. 



T. lepidoptera (Greg.) Cl. 



Cl. 1. c. p. 25. Amphiprora I. Greg. Diat. of Clyde p. 505, pi. XII, f. 59 a, b 

 (non c). Van Heurck Synops. p. 120, pi. 22, figs. 2 — 3. 



Not unfrequent: Stamsund -f-, Svolvser r, the Ostnesfiord r, 

 Stene r -| -, Gaukvsero r. 



Distribution: Coasts of the North Sea and Western Europe. 

 Finmark. The Mediterranean. West Indies. Indian Ocean. Pacific 

 Ocean. 



Donkinca Kalfs. 



D. recta (Donk.) Grun. 



Grun. in Van Heurck Synops. p. 119, pi. 17, f. 9. Plewosigma r. Donk. 



Micr. Jonrn. VI, p. 23, pi. 3, f. b'. Gyrosigma r. Cl. Synops. Navic. Diat. I, 



p. 119. 



Very rare: Stamsund, r. 



Distribution : Coasts of the North Sea and Western Europe. 

 The Mediterranean. Florida. Pacific Ocean. Indian Ocean. 



D. earinata (Donk.) Ralfs. 



Ealfs in Pritch. Inf. p. 921. Van Heurck Traite d. Diat. p. 248, pi. 35, f. 912. 



Pleurosigma c. Donk. Micr. Journ. VI, p. 23, pi. 3, f. 5; Cl. 1. c. p. 44. 



Rare: The Ostnesfiord r, Stene r, Gaukvsero r. 

 Distribution: Coasts of the North Sea and Ireland. Sea of 

 Kara. Davis' Strait. Balearic Islands. 



