EOCENE FERNS. C7 



13. Anemia subcretacea, Saporta. (Page 45.) 



Anemia subcretacea is very abundant and well preserved, and in one instance nearly 

 an entire frond was obtained from Bournemouth. It seems essentially characteristic of 

 the older Eocene, and even pre-Eocene Rocks, and has never been found in horizons 

 higher than that of Bournemouth in Europe, and the lowest stage of the Great Lignitic 

 in America. To the same group belong, without doubt, the Eern described as Asplenimi 

 Johnstrupi and A. Dicksonianum, Heer, from the Cretaceous Koraeschichten of Greenland^ 

 and Asplenium Forsteri, from Aix-la-Chapelle. They possess the same strength and 

 peculiar dichotomy in the stipes and vernation, the same graceful cutting in the leaves and 

 easy flowing venation, the same universal absence of sori, plainly indicating that they 

 could not belong to Asplenium. A. Nordenakidldi and A. hyperborea may be smaller 

 species belonging to the same genus, and Sphenopteris eocenica of Europe and America 

 should certainly be linked with it. 



These varieties might be united into at most two or three species. The larger, a 

 singularly well-marked form, ranged from the South of France to the Arctic regions, 

 though, perhaps, not synchronously, and first appears in the Cretaceous, and somewhat 

 suddenly disappears in the Middle Eocene. It bears no very striking resemblance to any 

 existing Fern, but the one most like it is Anemia adiantifolia, indigenous to America from 

 Florida to Mexico and Bahia. The fossil form appears to have attained its greatest 

 luxuriance in the Eocenes of temperate latitudes, and there is a marked difierence in this 

 respect between the average of our specimens and those from the Arctic regions. 



14. Lygodium Kaulfussi, Heer. (Page 47j 



The fossil is found in Central Europe, France, England, and the United Stales, and 

 is essentially a Middle Eocene Fern. A smaller and somewhat modified form seems to 

 have preceded it in the Cretaceous rocks of Aix-la-Chapelle. L. palmatum} indigenous 

 to Massachusetts and Florida, approaches it closely in some respects, but the Eocene 

 form was very much larger in the barren pinna, and the fertile pinnae were much smaller 

 and even more deprived of parenchyma. While possessing several characters of 

 L. palmatmn, it far more resembles Tropical species, such as L. dic/iotomum in size and 

 general mode of growth. No species of Lygodium have been met with among the 

 Arctic fossil flora, 



1 It is remarkable that all the fossil Lygodia belong to the section of L. palmatvm. The barren 

 fronds of the species found at Bournemouth are large compared to those from other Eocene, Oligocene, 

 and Miocene localities, jet no differences are perceptible between any of them in the fertile fronds. 



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