The American Species Referred to Thinnfeldia 
By EpwArD W. BERRY 
The genus Thinnfeldia was established by Ettingshausen in 
1852 * to include certain fern-like remains from the European 
Jurassic, which from their resemblance to the living species of 
Phyllocladus he referred to the Coniferae. Considerable diversity 
of opinion has since existed as to their true affinity, Thus Schenk 
considers them members of the Cycadales, while F. Braun refers 
them to the Filicales, where they are admitted by both Schimper 
and Saporta, and formerly by Nathorst, though latterly he regards 
them as Conifers. Potonie (Natiirlichen Pflanzenfamilien, 1900) 
includes the genus among the Filicales of the tribe Pecopterides, 
but he evidently does not include the American or Arctic species 
which have been referred to this genus. 
In 1874 Oswald Heer described a species from the Cretaceous 
of Spitzbergen as Thinnfeldia arctica (incorrectly spelled 7/in- 
feldia by him). Turning to this country we find Lesquereux in 
_ 1868 describing a species from the Dakota group as Phyllocladus 
subintegrifolius. Subsequently Heer described apparently identical 
remains, which were found in considerable abundance in the Atane — 
beds of Greenland, transferring them to the genus 7hinnfeldia and 
renaming the species Thinnfeldia Lesquereuxiana, classing it under 
the heading “ Incertae sedis’’ directly following the ferns. 
In 1889 Fontaine described three species of 7, hinnfeldia from 
the Potomac formation of Virginia, including them among the 
ferns, where they are undoubtedly rightly placed. Additional 
species from various American localities have been noted or char- 
acterized by Newberry, Hollick, Fontaine and Knowlton. It is 
obvious from the foregoing that the genus is a rather indefinite one 
not well understood and badly in need of revision, which task I 
have attempted for the American species. I have not included 
the European species because of lack of material. Judging from 
those I have seen figured and from Lesquereux’s remarks on 
mare 
* Ettings. Abhandl. k. k. Geol. Reichsanstalt, 13: no. 3, 2. 1852. 
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