2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



ACKNOWLEDGMENTS 



In addition to the Geological Survey personnel above mentioned as 

 having discovered the occurrence of Paleocene mammals in the Bison 

 basin, acknowledgment is due George N. Pipiringos, James Mac- 

 Lachlan, Dr. J. R. Hough, and Robert DeMar for having given field 

 aid in 1953. Dr. Paul O. McGrew aided in turning over, for the pur- 

 poses of this study, collections obtained for the University of Wyo- 

 ming in 1953. Particular mention may be made of interest shown in 

 this work by Dr. Roland W. Brown in having first called my atten- 

 tion to the occurrence, and in his marked contribution to the field col- 

 lecting in both 1952 and 1953, as well as being an original discoverer. 



Acknowledgment is made of aid no less important from Drs. George 

 G. Simpson, Edwin H. Colbert, Bobb Schaeffer, and Mrs. Rachel H. 

 Nichols in permitting me to examine and make comparisons with vari- 

 ous Paleocene collections in the American Museum and from Dr. 

 Glenn L. Jepsen in making available type and other materials in the 

 extensive Polecat Bench Paleocene collections at Princeton University. 



The drawings depicting the specimens shown in plates i to 1 1 were 

 made by Lawrence B. Isham ; those of Caenolambda patter soni in 

 plates 12 to 14 by William D. Crockett. 



HISTORY OF INVESTIGATION 



Following discovery of the fossil materials by the U. S. Geological 

 Survey party in July 1952 ^ and their reference to me for study and 

 report, the results of a preliminary examination were presented before 

 the Cambridge meeting of the Society of Vertebrate Paleontology in 

 November. During the later part of 1952 and early in 1953, Wallace 

 G. Bell, a graduate student at the University of Wyoming, engaged 

 in a thesis study of the geology of a rather general area including the 

 Bison basin, and Paul McGrew made collections at certain of the fos- 

 siliferous sites. Agreement was early reached whereby the University 

 of Wyoming party would join with the Smithsonian Institution-U. S. 

 Geological Survey expedition in the search of these exposures in the 

 summer of 1953, and that I would be permitted to study and describe 

 the collections as a whole. 



In June 1953 a party from Washington consisting of Dr. Roland 

 W. Brown, Franklin Pearce, and myself was accompanied in the field 

 by Messrs. Pipiringos and MacLachlan. We were joined at the fossil 



1 A very cursory examination of these beds was made by the writer in 1951, 

 accompanied by C. L. Jenks, Jr., of the Shell Oil Co., but on the north side of 

 the basin where exposures are evidently quite barren of fossils. 



