Marine Plankton from tlie East-Greenland Sea. 263 



havs-Exp., Protophyta, 1897, p. 28, pi. IV, fig. 59; Nord. Plankton XIX, 

 1905, p. IG, fig. 9. 



This species is rather rare in the collection; it has been found 

 in a single sample from the pack-ice in 1906, in some samples from 

 Danmarks Havn in 1907 and 1908, and in several ones from the 

 coastal water and the pack-ice in 1908, but never commonly. The 

 time where it "flowers" must be very short in these high latitudes 

 as it has not been present in the June and July (first half) samples 

 from Danmarks Havn. No resting spores were seen. July — Sep- 

 tember. 



Distrib. Northern neritic species widely distributed along the coast 

 regions of the nortliern countries. 



3. Thalassiosira decipiens (Grun.) Jørgensen, Bergens Museums 

 Skrifter, 1905, p. 96, pi. 6, fig. 3; Gran, Nord. Plankton, 1905 XIX, 

 p. 17, fig. 10; Ostenfeld, Wiss. Ergeh. Aral See Exp., VIII, 1908, p. 144, 

 pi. 6, figs. 6— 8; T. gelatinosa Hensen, 5. Ber. Komm. Deutsch. Meere, 

 1887, p. 87 ; Coscinodisciis excentricus, var.? decipiens Grunow, Sitz- 

 ungsber. naturw. Ges. Isis, Dresden, 1878, p. 28, pi. 6, fig. 18; C. deci- 

 piens Grunow in Van Heurck, Synopsis, 1883, pi. 91, fig. 10. 



Found sparingly in four samples from the outer margin of the 

 pack-ice in 1906, not elsewhere. July— August. 



Distrib. Northern temperate s])ecies known from the coast regions 

 of North and West-Europe, further from the Caspian and Aral Seas; not for- 

 merly found in arctic water, wliere it lias not its home. 



4. Thalassiosira hyalina(Grun.) Gran, Bibliotheca bot. Heft 42, 

 1897, p. 4, pi. 1, figs. 17— 18; Nord. Plankton XIX, p. 17; E.Jørgensen, 

 Bergens Museums Skrifter, 1905, p. 96, pi. VI, fig. 5; Th. Clevei Gran, 

 Norske Nordhavs Exp., Protophyta, 1897, p. 29, pi. 4, figs. 60—62; 

 Coscinodiscus hyalinns Grun. in Cleve & Grunow, K. Svenska Vet- 

 Akad. Handl., Bd. 17, No. 2, 1880, p. 113, pi. 7, fig. 128; Grunow, Diat. 

 V. Franz Josefs Land, 1884, p. 30, pi. C, fig. 28. 



It is rather curious that I have found this species, so charac- 

 teristic for the ice-floes, only very rarely and in a few samples from 

 the pack-ice in August 1906. 



Distrib. Arctic-neritic species known from the ice-floes and the coasts 

 of the arctic Sea (reaching as far south as Stadt in Norway). 



5. Thalassiosira gravida Cleve, Bih. K. Svenska Vet. Akad. 

 Handl., Bd. 22, afd. 3, No. 4, 1896, p. 12, pi. 2, figs. 14—16; Gran, Norske 

 Nordhavs-Exp., Protophyta, 1897, p. 28, pi. 4, figs. 57—58; Nord. Plank- 

 ton XIX, p. 18, fig. 12; Coscinodiscus subglobosiis Cleve & Grun. in 

 Grunow, Diat. v. Franz Josefs Land, 1884, p. 32, pi. D, figs. 19—20. 



