EXPLORATIONS FOR FOSSIL VERTEBRATES. 567 



A third American Museum party was in the heart of the Laramie 

 plains of Wyoming, where in 1898 the ruins of a sheep herder's cabin 

 composed entirely of dinosaur bones led to the discovery of an ex- 

 traordinarily rich deposit of the great amphibious dinosaurs and other 

 reptiles of the Upper Jurassic age, which is roughly estimated as 

 6,000,000 years distant. The museum has been working in this same 

 quarry six years, and each year has taken out a very large freight car- 

 load, yet the deposit is still far from being exhausted. 



Stratified Deposits in the Bripger Basin, Southwestern Wyoming. 



A fourth expedition was in southwest Wyoming, just north of the 

 Uintah Mountains, nor far from the once famous Fort Bridger, a now 

 deserted army post. This middle eocene flood plain or lake basin dates 

 back about 2,500,000 years in its fauna, which embraces small ancestors 

 of the horses, about the size of a whippet hound, a great variety of 

 monkeys, hundreds of small quadrupeds remotely related to the tapirs, 

 including one especially large type. Also of the great Uintatherium 

 or Uinta beast, a very archaic type of quadruped, the discovery of 

 which between 1870 and 1873 aroused widespread interest in this 

 country. The museum party was very fortunate also in this region and 

 brought back remains of about five hundred individuals. In this col- 

 lection were one hundred and twenty-one turtles, chiefly found by Dr. 

 O. P. Hay, both river and land forms, some ancient, some surprisingly 

 modern in type, including species which are now only represented in 

 South America. 



During the summer of 1904 three expeditions went out from the 



