Reviews — Prof. 0. C. Marsh's Binocerata. 213 



" 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 vertebrate 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 Carnivores, Insecti- 

 vores, Eodents, 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. 



" The remarkable Eocene basin north of the Uinta Mountains, 

 where alone the Dinocerata had been found, offered so inviting a field 

 for exploration, that in the spring of the following year, 1871, the 

 author began its systematic investigation. An expedition was again 

 organized, with an escort of United States soldiers, and the work 

 continued during the entire season." 



In 1872, 73, 74, and 75, these researches were continued by Prof. 

 Marsh with unabated energy; finally, during the entire season of 

 1882, the work was again vigorously prosecuted by the author ; and 

 after July of that year, by the United States Geological Survey. 



The specimens brought together in Yale College Museum alone 

 represent more than 200 individuals of the Dinocerata, besides a vast 

 series of remains of other orders of animals. The author refers to 

 the early labours of Dr. Leidy (who proposed the name of TJinta- 

 iherium for certain specimens obtained by him) ; to Prof. Cope (who 

 proposed the names Loxolophodon, Eohasileus, and Bathyopsis for 

 various forms of Dinocerata which he had discovered). He also 

 credits the staff of the Princeton College, whose collecting parties 

 had secured numerous remains of Dinocerata and other fossils from 

 the same localities. But the far larger collections obtained by Prof. 

 Marsh for Yale College have left little to be desired in the way of 

 additional evidence for the completion of his Monograph. The 

 localities in which the Dinocerata have been found are on both sides 

 of the Green River, and mainly south of the Union Pacific Railroad 

 in Wyoming. About equal numbers of specimens were found east 

 and west of the Green River, the distance between the extreme 

 localities in this direction being more than one hundred miles. They 

 occupy a well-marked geological horizon of the Middle Eocene. 



" The Dinocerata form a well-marked order in the great group of 

 Ungulata. In some of their characters, they resemble the Artiodactijla ' 



1 Artioclactyla, or even-toed Ungulata, or hoofed animals (Pig, Hippopotami, 

 Camels, Deer, Antelopes, Sheep, Oxen, etc.). 



