X. AN ANNOTATED LIST OF FOSSIL PLANTS OF THE 

 DAKOTA FORMATION (CRETACEOUS) IN THE COL- 

 LECTIONS AT THE CARNEGIE MUSEUM, INCLUD- 

 ING DESCRIPTIONS OF THREE NEW SPECIES. 



By E. M. Gress, Ph.D. 

 (Plates XIV axd XV.) 



Introductory, 



The present paper embodies the results of an investigation carried 

 on in the Carnegie Museum under the direction of Dr. O. E. Jennings 

 and counted as a minor study in the Graduate School of the University 

 of Pittsburgh in candidacy for the Degree of Doctor of Philosophy. 

 A report of this investigation was given before the Paleontological 

 Society of America at the Pittsburgh meeting, held December 31, 

 1917, to January 2, 1918, but since that time has been considerably 

 elaborated. 



The specimens studied consist of leaf impressions, mostly in a 

 rather coarse-grained sandstone known as the Dakota Sandstone, 

 from Ellsworth County, Kansas. . Most of the specimens were ob- 

 tained by the Carnegie Museum when it acquired the collection of 

 Baron de Bayet; others were obtained a number of years ago by 

 exchange with the National Museum, while a few others are of mis- 

 cellaneous provenance, acquired in various ways, as may be noted in 

 the references to the specimens under the respective species in the 

 accompanying list. 



While of necessity considerable time was consumed in studies re- 

 lating to the stratigraphy and correlation of the Dakota and other 

 adjacent formations, in order that the literature might be used with 

 facility and some considerable degree of assurance, nevertheless the 

 studies were carried out more from the standpoint of a botanist than 

 of a geologist. The work was done in the Herbarium of the Carnegie 

 Museum, where constant reference was possible to specimens in con- 

 nection with the more detailed studies of venation and other char- 

 acters of the leaves of certain species, or groups of species. 



274 



