ANCESTORS OF MAMMALS 21 



and the bed of the old lake exposed ; to-day it is known as 

 the Mauvaises Terres, or Bad Lands, through which ex- 

 plorers ride or walk, hunting for the bones of the giants 

 which once lived in the old lakes. 



No more fascinating hunt can be imagined than this. 

 Here is found the head of some monster ; a ravine has cut 

 away the center portion, and on the opposite butte are 

 found the legs. For years these skeletons and bones were 

 found by herders, and used for various purposes ; then 

 when their value was appreciated, they were collected and 

 sold to the great museums of the world. I well remember 

 passing through similar " Bad Lands " between Salt Lake 

 and the coast. Tall buttes rose in every direction, colored 

 in all the splendid tints of the rainbow, telling of the wear 

 and tear of centuries. They seemed to be the spires of 

 churches, towers of castles. 



In the Bad Lands are the monuments of a lost race. 

 Professor Marsh discovered this marvelous Eocene col- 

 lecting ground in 1870, and investigated it with a guard of 

 troops as a protection against the Indians who, as might be 

 expected, had no interest in science or sympathy with its 

 disciples. In the lands east of the Rocky Mountains, in 

 Nebraska, Dakota, and in Colorado, he discovered many 

 strange mammalian remains. One of the largest was 

 the Brontops (Fig. 15), which lived on the borders of an 

 old lake in the Miocene time. It was, in effect, an Ameri- 

 can rhinoceros, twelve feet long, eight feet high, with a 

 pecuHar head calling to mind the rhinoceros. The head 

 was three feet long and twenty inches between the tips of 

 the two enormous blunt tusks that stood side by side. In 

 all probability this uncanny monster had a long flexible 



