Report upon United States geological surveys west of the one hundredth meridian, Volume IV: Paleontology

I [G.M. Wheeler] have the honor to submit herewith a report, in two parts, upon the paleontological results arising from the collections and examinations made during the years 1871, 1872, 1873, 1874, and 1875, in connection with geographical explorations and surveys west of the one hundredth meridian, for publication as Volume IV of the reports authorized by acts of Congress approved June 23, 1874, and February 15, 1875.