FLORA OF THE DAKOTA GROUP. 1 1 )J 



Cenomanian of Europe in divers localities indicated in the table, is the least 

 distinctly marked with Quedlinburg. From this place Heer has described 

 20 species, 3 of which only — Grleichenia Kurriana, Sequoia Reichenbachi . and 

 Proteoides lancifolius — are identified in the Dakota Group. The stage of 

 the Quedlinburg beds is not positively determined. While some geologists 

 refer it to the Cenomanian, Goeppert considers it as lower Senonian. or as 

 a formation more recent than that of the Cretaceous of Kansas. It has a 

 t '/xlneria (V. mtegerrima, Zenk.), also found at Atane. The flora of Moletiin 

 offers, in nearly the same number of species (18), more definite points 

 of affinity with that of the Dakota Group in 7 identical species, 3 of which 

 are dicotyledonous: Ficus Mohliana, Aralia formosa, and Magnolia sjjeciosa. 

 The Moletein formation is generally admitted as equivalent to that of the 

 lower Quader sandstone of Germany, from which at different localities in 

 the Hartz and in Bohemia 30 species of plants have been described. Of 

 these, also, 8 are found in the Dakota Group. Hence the marked analogy 

 in the components of these floras authorizes the conclusion of equivalent v 

 of the age of the Dakota Group with that of the Quader sandstone oi 

 Germany, which is as positively determined as Cenomanian by its animal 

 fossils as the Dakota Group is recognized as Middle Cretaceous by the in- 

 vertebrate remains which abound in the strata of the Fort Benton Group, 

 immediately overlying it. 



We may have an opportunity to see in the characters of the plants 

 further described in this volume, from the different stages of the Tertiary, 

 some of the types of the Dakota Group reappearing through subsequent 

 periods, especially in the Miocene. But this cannot in any way nullify 

 the originality of these types, and what is said above sufficiently proves 

 that if the Dakota Group has in its flora some plants closely allied to 

 Miocene species, and also to plants living at the present time, the Cre- 

 taceous age of the group is positively fixed. 



