( ii:< >logical Series 



Field Columbian Museum. 

 Publication 75. 



Vol. II, No. 1 



NORTH AMERICAN 



PLESIOSAURS. 



PART I. 



\\X 



Samuel \Y. 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. 



