vi Preface. 



?"ossil mammals 9)°73 



Fossil reptiles 2,694 



Fossil birds 57 



Fossil amphibians 593 



Fossil fishes ■ J'^^^i 



Total 14.420 



Beginning in 1891, the hori/.ons have been explored in the following 

 order : 



Permian, Texas, 1902. 



Triassic, North Carolina, 1894, 1895. 



Upper Jurassic (Como Beds), Wyoming, 1897-1903 ; Montana, 1903. 



Upper Cretaceous (Niobrara), Kansas, 1897. 



Upper Cretaceous (Fort Pierre), South Dakota, 1903. 



Upper Cretaceous (Laramie), Wyoming, 1892, 1900; Montana, 1902. 



15asal Eocene (Puerco), New Mexico, 1892. 



Basal Eocene (Torrejon), New Mexico, 1892, 1896. 



Lower Eocene (Wasatch), Wyoming, 1891, 1896; New Mexico, 1896. 



Middle Eocene (Wind River), Wyoming, 1891, 1896 ;, Colorado, 



1897. 



Middle Eocene (liridger), Wyoming, 1893, 1895, 1903 ; Colorado, 



1897. 



Upper Eocene (Uinta), Utah, 1894, 1895. 



Oligocene (White River), South Dakota, 1892, 1894, 1901, 1902. 



Oligocene (White River), Colorado, 1898, 1901 ; Montana, 1902. 



Middle Miocene, Colorado, 1898, 19.01, 1902. 



Upper Miocene (Loup Fork), South Dakota, 1894, 1902, 1903. 



Upper Miocene, Texas, 1899, 1900, 1901 ; Montana, 1902. 



Pliocene (Blanco), Texas, 1900, 1901. 



T'leistocene (Sheridan), Nebraska, 1893, 1897 ; Texas, 1899, 1900, 

 1901. 



Pleistocene Arkansas, 1903. 



General Exploration. — Two series of expeditions, 

 for inammals and for reptiles, conducted by from two 

 to four parties, have been sent out each year since 1897 

 in the systematic search for fossil reptiles and mammals 

 in different formations. 



These expeditions during the past five years, namely 

 between 1 898 and 1 903. have had a considerable meas- 

 ure of success. They have added some 2,500 speci- 



