Paleontology 687 



of the number and character of the species. Two of the 

 species of ox described by Doctor Leidy belong to the 

 genus Bison, and one of these is of gigantic size. The other 

 two species belong to a new genus called Bootherium, which 

 has been shown to be identical with Ovibos. 



The material upon which the ancient fauna of Nebraska is 

 based came from the drainage region of the Missouri, from the 

 tract of country known by the name of " Mauvaises Terres," or 

 the " Bad Lands." This at one time was the bottom of an im- 

 mense lake, in which thousands of animals, having no repre- 

 sentatives at this time on the surface of the earth, perished. 

 The age of the beds is lower Miocene or Oligocene, and their 

 special name in the closer divisions of formations is the White 

 River Beds of Hayden. 



This region having been brought to notice by a few fossil re- 

 mains procured through the agents of the American Fur Com- 

 pany, an appropriation of about $200 for its exploration was 

 made by the Smithsonian Institution to Mr. Thaddeus Cul- 

 bertson, who was about to visit, on account of his health, the 

 sources of the Missouri. The specimens of fossil remains which 

 were thus procured, together with a collection subsequently 

 presented to the Institution by Captain Stewart Van Vliet, 

 of the United States army, and several specimens kindly lent 

 by Doctor Prout, of Missouri, were referred to Doctor Leidy 

 for examination. In addition to these he had the use of a col- 

 lection lent by Professor O'Loghland, of Missouri, specimens 

 belonging to the Academy of Natural Sciences, Philadelphia, 

 and a collection made by Doctor Evans, at the instigation of 

 Doctor D. Dale Owen, the whole embracing all the specimens 

 which had yet been brought to the East from the Bad Lands. 

 The bones were completely petrified, and their cavities filled 

 with silicious matter. They were preserved in various degrees 

 of integrity, some being beautifully perfect and others broken 



