1)11. LEIDY'S MEM OIK. 



The region of Nebraska Territory of the United States appears to be as rieli in 

 the remains of MaraniaUa and Chelonia of the Eocene period as the deposits of tlie 

 same a"-e of the Paris basin. Dr. Hiram A. Prout of St. Louis, described the first 

 mammalian fossil from Nebraska, in the American Journal of Science for 1847. 

 The specimen indicates a species of Pahvotherium, or of a closely allied gemis of 

 gigantic size, and has been named after its discoverer, Palo3otlierium Proutii, Oicen, 

 Norwood, and Ecans. Since the account of this fossil was published, an extraordi- 

 nary number of l)eautiful and highly important specimens, of new species and genera 

 of extinct Mammalia and Chelonia iiave been derived from the same locality, through 

 the combined influence and labours of Messrs. Joseph and Thaddeus Culbertson, 

 Professor Baird, Drs. D. D. Owen, Norwood, and Evans, and Dr. H. A. Prout and 

 Professor 0. Loghland. The most valuable collection, obtained by Dr. Owen's 

 surve}^, forms the basis of the following descriptions, and comprises numerous speci- 

 mens of eit^ht species of six genera of Mamnuilia, and four species of the chelonian 

 genus Tcstudo. 



All the genera of Mammalia are distinct from those now in existence, and half of 

 the number are new to Pah\.^ontology. 



Among all the specimens which have come under my observation from Nebraska, 

 one only belongs to a true carnivorous animal, and this is the Machairodus prima*- 

 vus, Leidy and Oicen. 



All the other mammalian fossils belong to the order Pachydermata, as Paljcothe- 

 rium and Rhinoceros, or to this order combined with ruuiinating characters, as 

 in the case of Oreodon and Eucrotaphus; or to the same order in combination with 

 decided carnivorous characteristics, as in the Archa^otherium. 



Most of the bones and their fragments arc in a relatively good state of preserv^v 

 tion, and are highly mineralized. Those of smaller animals are less fractured and 

 mutilated than those of larger animals. The latter in many cases are crushed, 

 while the fragments still retain their relative position, and the interstices fdled 



