2 DINOCERATA. 



This same action has brought to light the remains of many extinct 

 animals, and the bones of the Dinocerata, from their great size, naturally 

 first attract the attention of the explorer. 



The first remains of the Dinocerata discovered were found by the 

 author, in September, 1870, while investigating this Eocene lake-basin, 

 which had never before been explored. Various remains of this group 

 were also collected by other members of the expedition, and among the 

 specimens thus secured was the type of Tinoceras anceps, described by the 

 author in the following year, and now more fully in the present volume. 

 In the same geological horizon with these remains, a rich and varied 

 verteljrate fauna, hitherto unknown, was found. 



Among the animals here represented were ancestral forms of the 

 modern horse and tapir, and also of the pig. Many others were found 

 related to the recent Lemurs ; also various Carnivors, Insectivors, 

 Rodents, and small Marsupials ; and of still more importance, remains 

 were here brought to light of another new order of mammals, the 

 Tillodonts, quite unlike any now living. Crocodiles, tortoises, lizards, 

 serpents, and fishes also swarmed in and about the waters of this ancient 

 lake, while around its borders grew palms, and other tropical vegetation. 



A later Eocene lake-basin, south of the Uinta Mountains, was 

 discovered, in October, 1870, by the same expedition, and named by 

 the author Uinta basin. In the attemjit to explore it, our party endured 

 much hardship, and also were exposed to serious danger, since we had 

 only a small escort of United States soldiers, and the region visited was 

 one of the favorite resorts of the Uinta Utes. These Indians were then, 

 many of them, insolent and aggressive, and since have been openly 

 hostile, at one time massacring a large body of government troops sent 

 against them. Two subsequent attempts by the author to exjdore this 

 basin met with little success. This lower lake was of upper Eocene age, 

 and its extinct fauna appears to correspond more nearly to that of the 

 Paris basin than any other yet discovered in this country, i 



' Some results of tWs Expedition may be found in an article by the author on the 

 "Geology of the Eastern Uintah Mountains," American Journal of Science and Arts, 

 vol. i, p. 191, March, 1871. 



