FOSSIL FLORAS OF ARCTIC REGIONS — NATHORST. 339 



The most ancient Jurassic sediments of Spitsbergen are marine, 

 and belong to the Sequanian stage. There was consequently a long 

 interruption in sedimentation after the formation of the Rhsetic 

 beds. 1 The upper part of the Jurassic formation (Portlandian) 

 furnishes a series of plant-bearing sandstones, seams of coal, and beds 

 of undoubted fresh-water origin, containing TJnio and Lioplax polaris. 

 The fossil plant remains belong to two different floras, 2 one, the more 

 ancient, being characterized by the presence of Ginkgo digitata 

 Brongn., sp.; the other, the more recent, by Elatides curvifolia Dkr., 

 sp. The two floras are associated with beds of coal, and one may 

 here also put forward the view that the plants originally flourished in 

 the place where they are now found. One of the coal seams at Cape 

 Boheman furnishes a great abundance of Podozamites and Pityojiliyl- 

 lum; sometimes the surface of the schists is as completely covered 

 with the leaves of Ginkgo digitata, as the soil beneath a living ginkgo 

 tree may be in autumn. Since branches and seeds of the same plant 

 are also associated, it is natural to suppose that a ginkgo forest 

 occurred not far away from this spot. The same observation applies 

 to Elatides curvifolia of the more recent flora, which occurs locally in 

 the fresh-water beds containing Unto and Lioplax. Floras of the 

 same age and composition are also known from King Karls Land, the 

 islands of New Siberia, 3 from Northern Siberia, and Arctic Alaska. 



The Neocomian series of King Karls Land is overlain by sheets of 

 basalt, often amygdaloidal, and containing chalcedony and agates. 

 Fragments of silicifled woods, large and small, also occur here, and 

 these, without doubt, owe their mineralization to the volcanic 

 phenomena. Some of these trunks are fairly large, and I have 

 myself measured one, which, although incomplete, was 70-80 cm. 

 in diameter, and showed 210 annular rings. Some of these remains 

 consist of the lower portion of the trunk and the primary ramifica- 

 tions of the roots. 



The microscopic examination of these specimens, undertaken by 

 Dr. W. Gothan, 4 has shown that the annual rings of the fossil stems 

 from King Karls Land were much more accentuated than those of 

 stems found in the corresponding beds of the European continent, 

 which indicates that the trees lived in a region where the difference 

 between the seasons was extremely pronounced. They can not there- 

 fore have been transported from the south by marine currents, and as 



i A. G. Nathorst, " Beitrage zur Geologie der Baren Insel, Spitzbergens, und des Konig Karl Landes": 

 Bull. Geol. Inst. Upsala, vol. 10, 1910. 



2 A. G. Nathorst, "Zur Mesozoischen Flora Spitzbergens": Kongl. Svenska Vet. Akad. Handl., vol. 30, 

 No. 1; Stockholm, 1S97. 



s Id., "tjber Trias und Jurapflanzen von der Insel Kotelny": Wm. Akad. Imp. Sei. St. P^tersbourg, 

 ser. 8, vol. 21, No. 2, 1907. 



* W. Gothan, "Die fossilen Holzer von Konig Karls Land": Kongl. Svenska Vet.- Akad. Hand!., vol. 43, 

 No. 10; Stockholm, 1907. 



