Flora of the Dakota group.] De ota, de ae ei ? 
are referable to the Urgonian or Lower Cretaceous, a group of plants has been dis- 
covered composed of 1 algoid, 3 ferns, 12 Cycadee, 5 conifers and ‘1 monocotyledon. 
The characters of these plants are like those of the plants of the Wealden and of the 
Jurassic. In Greenland, the Swedish expedition under the direction of Nordens- 
kidld also found at Korne, in strata which by their fauna are referable to about 
the same geological subdivision of the Lower Cretaceous as the Vernsdorf schists, 
a group of 8S species of plants representing 48 ferns, 1 Marsilia, 1 Lycopod, 
3 species of Equisetum, 14 Zamiew, 17 conifers, 5 monocotyledons with a few frag- 
ments of a leaf of a dicotyledonous species, a Populus which Heer, who has examined 
and determined the plants, has named Populus primeva. Here still we find precisely 
the same elements of vegetation as in the Wealden and the Jurassic, except that 
leaf of Populus. 
It is from this point or from above the lower Urgonian subdivision that 
appear the earlier American Cretaceous strata, those of the Dakota group, imme- 
diately superposed, in the western states to the Permian magnesian limestone. 
Above this formation and up to the base of the Tertiary, one passes, in ascending 
through the four geological subdivisions fixed by Hayden and Meek, the Benton, the 
Niobrara, the Fort Pierre and the Fox Hill groups. The fauna of the Benton group 
is that of the Cenomanian of d’Orbigny; by its position the Dakota group is referable 
to the same subdivision, while its flora is that of the Middle Cretaceous of Greenland 
and of the Quader sandstone of Germany. Its geological stage is thus positively 
fixed as succeeding the Urgonian, where, as seen above, the types of the vegetation 
are still mostly Jurassic and without any trace of dicotyledons, except that Populus 
found by Heer among the 88 species of Korne. Now, the flora of the Dakota group 
is of a totally different character. As known at the present it has in more that 200 
species of plants which have been determined, 1 Hquisetum, 6 ferns, 6 Cycadew, 10 
conifers, 3 monocotyledons and 175 dicotyledons, these being in the proportion 
of 81 per cent. while the other .groups of plants, including the monocotyledons, 
remain relatively the same. The flora of Atane which has been discovered in 
Greenland in strata at a higher stage of the Cretaceous than that of Korne, and 
which is also referable to the Cenomanian by its fauna, has about the same elements 
in its composition. In 177 species described by Heer, it has 3 Fung: (Hyporylee upon 
leaves of dicotyledons), 31 ferns, 1 Marsilia, 1 Selaginella, 1 Equisetum, 11 Cycadee, 24 
conifers, 8 monocotyledons and 97 dicotyledons, or a proportion of 55 per cent. of 
dicotyledons. This group of plants has a greater number of ferns and conifers than 
that of the Dakota group, a difference evidently due to the influence of local atmo- 
spheric circumstances. In collections recently made of plants of the Dakota group, 
