Mr. L. F. Ward on Mesozoic Dicotyledons. 391 
have adopted divisions for their geological formations corre- 
sponding to the character of the rocks in each country. These 
divisions cannot be made to harmonize with exactness when it 
is sought to compare widely separated regions. The attempt 
here made to correlate the subdivisions of the Huropean, 
Arctic, and North-American Cretaceous can therefore at best 
only lay claim to approximate accuracy. 
The Quadersandstein of Germany, in which the greater 
part of the Huropean fossil plants have been found, is an ex- 
tensive formation, reaching in Saxony and Bohemia from the 
Lower Cenomanian to the White Chalk, or Upper Senonian. 
Its middle portion is occupied by the Pliner sandstone and 
Pliner marls, which extend downward into the Upper Ceno- 
manian and upward to the base of the Senonian. The some- 
. what local character and indefinite boundaries of the Quader 
formations have rendered it customary on the Continent, even 
with German geologists, to adopt the system of D’Orbigny as 
now modified, and to speak of the Cenomanian, Turonian, and 
Senonian instead of Lower Quader, Pliner, and Upper Quader; 
and it is also now common to apply these terms to formations 
in other parts of the world which are supposed to occupy the 
same stratigraphical positions. 
The leading European localities from which Cretaceous 
Dicotyledons have been collected are—Saxony (Niederschéna), 
Moravia (Moletein), Bohemia (Trziblitz, Perutz), Silesia 
(Oppeln, Tiefenfurth), the Harz district (Blankenburg, Qued- 
linburg), Westphalia (Legden, Sendenhorst), and the vicinity 
of Aix-la-Chapelle. The first four of these localities belong 
to the Lower Quadersandstein, or Cenomanian, that of Nieder- 
schéna lying near its base. The Cretaceous of the Harz 
district is probably Lower Senonian. In Westphalia, Hosius 
and Von der Marck find fossil Dicotyledons at two different 
horizons, both of which, however, they place in the Senonian. 
The region about Legden, Ahaus, Haltern, &c. is regarded 
as Lower Senonian, while Sendenhorst, Haldem, &c. dre 
said to be Upper Senonian. The iron-sand near Aix-la- 
Chapelle is probably still higher, and occupies the extreme 
Upper Senonian. 
The next greatest source, outside of the United States, of 
the class of fossils under consideration is Greenland. The 
Kome beds, as already remarked, are distinctly fixed in the 
Urgonian, which is Lower Cretaceous, and lies between the 
Neocomian and the Gault. The discovery of a dicotyle- 
donous plant at this horizon is one of the most interesting 
facts of paleontological science. The beds of Atane, where 
the greater part of the species were found, although called 
