CRETACEOUS AND TERTIARY FORMATIONS 541 



have been removed. It was only by the erosion of this entire 

 formation that the Lance beds have been exposed along the Yellow- 

 stone and Missouri rivers and elsewhere, since the Fort Union 

 formerly covered the entire region. 



The Fort Union beds, which are early Eocene in age, contain 

 a flora of nearly 400 species, and a fauna comprising both inverte- 

 brates and vertebrates. The plants contained in the following 

 lists were found in the yellow and light gray beds forming the lower 

 part of the formation. Most of them occurred either in concre- 

 tions or in layers of sandstone. 1 



NEAR MEDORA, NORTH DAKOTA 



Sequoia Nordenskioldi ,Heer. Populus daphnogenoides Ward. 



Populus cuneata Newb. Populus glandulifera Heer. 



Ulmus planeroides Ward. Planera microphylla Newb. 



Populus Richardsoni Heer. Carpites n. sp. 



Populus amblyrhyncha Ward. Taxodium occidentale Newb. 



Sapindus grandifoliolus Ward. Diospyros brachysepala Al. Br. 



Viburnum antiquum (Newb.) Hoi. Asplenium tenerum. 



MOUTH OF DEEP CREEK, SOUTHERN BILLINGS COUNTY, NORTH DAKOTA 



Viburnum Newberrianum Ward. Viburnum asperum Newb. 



NORTHERN BILLINGS COUNTY, NORTH DAKOTA 



Equisetum sp. Viburnum antiquum (Newb.) Hoi. 



Viburnum Newberrianum Ward. Viburnum Whymperi ? Heer. 



Diospyros — may be D. ficoidea Lesq. Corylus rostrata? Ait. 



or new. Taxodium occidentale Newb. 



Platanus nobilis Newb. Pterespermites Whitei ? Ward. 



WESTERN BURLEIGH COUNTY, NORTH DAKOTA, NEAR THE BASE OF THE FORT 

 UNION AT ELEVATION OF ABOUT 4OO FEET ABOVE MISSOURI RIVER 



Populus daphnogenoides Ward. Platanus Haydenii Newb. Young 



Populus amblyrhyncha Ward. leaf. 



Populus cuneata Newb. Viburnum sp. 

 Aralia notata Lesq. 



CENTRAL BURLEIGH COUNTY, NORTH DAKOTA, NEAR BASE OF THE FORT UNION 



Populus daphogenoides Ward. Platanus nobilis Newb. 



Populus sp. ? Grewiopsis populifolia Ward. 



Populus amblyrhyncha Ward. Euonymus ? sp. 



1 The plants were identified by Dr. F. H. Knowlton. 



