Field Columbian Museum. 

 Publication 73. 

 Geological Series. 



Vol. II, No. 1 



NORTH AMERICAN 

 PLESIOSAURS. 



PART I. 



BY 



Samuel W. Williston, M.D., Ph.D., 



Associate Curator, Division of Palaeontology; 

 Professor of Palaeontology, University of Chicago. 



Oliver C. Farrington, Ph.D., 

 Curator of Geology. 



Chicago, U. S. A. 



April, 1903. 



