SOME AMERICAN MONSTERS. 159 



never before been explored. It was here, also, that he found the 

 wonderful series of fossil horses by means of which he has been 

 able to prove that our modern horse is descended from a small 

 quadruped with five toes, and to show the different stages in its 

 evolution. Here, also, were found old-fashioned types of car- 

 nivorous quadrupeds, of rodents, and of insectivorous creatures. 

 But reptiles as well as quadrupeds flourished on the borders 

 of the old lake, for the remains were found of crocodiles, 

 tortoises, lizards, and serpents ; its waters, too, were well stocked 

 with fish. 



Everything here testifies to a long continuance of those con- 

 ditions under which plant and animal life can flourish, namely, a 

 warm climate, plenty of food, and freedom from those physical 

 changes which, by altering the geographical features of a country, 

 bring so many important consequences in their train. The 

 geological record tells us that this happy state of things lasted 

 all through the Eocene period, and until the fresh-water lakes 

 had at last been drained away by their outflowing rivers. 



In October, 1870, a later Eocene lake-basin was discovered by 

 the same exploring party, and this Professor Marsh calls the 

 Uinta basin, because it was situated south of the Uinta Moun- 

 tains. " In the attempt to explore it," he says, " 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 favourite 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 ... to explore this region met with litde success." 



This lower lake was of later (or upper) Eocene age, and the 

 extinct animals preserved in its ancient bed appear to resemble 

 more nearly those of the famous Paris basin, referred to in the 

 beginning of this chapter, than any yet discovered in America. 

 But the basin north of the Uinta Mountains, where alone the 



