THE LOWER CRETACEOUS FLORAS 

 OF THE WORLD 



BY 



EDWARD W. BERRY 



Intkoductory 



The Lower Cretaceous^, because of the thickness of its deposits, the 

 time interval which it embraces, and the resulting change in plant and 

 animal life, has been considered by certain American geologists to con- 

 stitute one of the major divisions of the geological column under the 

 name Comanchean, although the utility of this term and its ultimate 

 sur'\dval is doubtful. Invertebrate paleontologists have taken the lead in 

 determining its subdivisions, the main criteria being the succession of the 

 molluscan faunas, among which the Cephalopoda and the aberrant 

 Eudistse, Chamida), etc., are chiefly relied upon. 



Since, except for the initial Cretaceous deposits both in this country 

 and abroad, the conditions in the materials preserved from erosion and 

 available for study are mainly those of marine deposition, fossil plants are 

 unrepresented or only partially represented at a large number of levels. 

 Consequently, they occupy a secondary place in the paleontological cor- 

 relation of the Lower Cretaceous as a whole. These floras are, however, 

 of extraordinary interest, since toward the close of the Lower Cretaceous 

 modern types make their appearance in considerable numbers, and it 

 seems probable that the evolution of the angiosperms, the dominant class 

 of the Tertiary and post-Tertiary floras, was accomplished if not inau- 

 gurated during this period. 



While the nomenclature of the subdivisions of the Lower Cretaceous 

 varies in different countries and with different authors the following of 



