S. GEOGRAPHICAL AND GEOLOGICAL SURVEY OF THE ROC1Y MOUNTAIN REGION. 



J. W. FO^VELL, IN CHARGJ-H5. 



PRELIMINARY REPORT 



OX THE 



PALEONTOLOGY OF THE BLACK HILLS, 



BY 



R. 



CONTAINING DESCRIPTIONS OF NEW SPECIES OF FOSSILS FROM THE 



POTSDAM, JURASSIC, AND CRETACEOUS FORMATIONS 



OF THE BLACK HILLS OF DAKOTA. 



WASHINGTON: 



GOVERNMENT PRINTING OFFICE. 



July, 1877. 



