SMITHSONIAN EXPLORATIONS, I93O 1 5 



bottom. Looking about for stones with which to block up the wheels, 

 we noticed a rocky layer protruding from the bank and Pearce was 

 instructed to get the pick and pry out some of it for ballast. A stroke 

 or two with the pick brought an exclamation of surprise, for on the 

 under side of the first slab detached was the complete skull of a croco- 

 dile in excellent preservation. A most happy surprise and a valued 

 addition to our then small accumulation of fossils. 



On June ti, camp was moved to a site on Leavitt Creek and here 

 we were successful in finding some of the best collecting ground yet 

 encountered. Four weeks of collecting here brought us past the middle 

 of the season and inasmuch as all of our work had been in the lower 

 half of the formation, it was decided to move to a locality where the 

 upper measures offered good collecting ground. Accordingly on 

 July 16 our fourth and last camp was established on Henry's Fork, 

 about a mile north of Lone Tree postoffice and here the remaining 

 weeks of the season were profitably spent. 



As a result of this work a great mass of material was accumulated 

 which is thought to contain much of scientific interest and importance, 

 in addition to some few specimens of an outstanding character. The 

 collection filled 24 large cases having a combined weight of 7,430 

 pounds. 



Among the specimens of outstanding interest are an almost complete 

 articulated skeleton of Hyrachyus, a rhinoceros-like animal about the 

 size of the modern tapir ; a skeleton slightly less complete of Orohippus, 

 a small primitive horse ; two partial skeletons of Palaeasyops and two 

 crocodile skeletons that are more or less complete. At least four mount- 

 able skeletons for the exhibition series will result from the above 

 mentioned materials. In addition there are many parts of skeletons, 

 i. e., skulls, jaws, articulated limbs and feet of both large and small 

 mammals. 



From a scientific point of view, the small mammal material such as 

 tooth-filled jaws and parts of skulls in some instances associated with 

 parts of skeletons, may prove to be the more important part of the 

 collection. In all there were nearly 200 such specimens coming from 

 all horizons, ranging from near the base to the top of the formation, 

 representing beds of not less than 1,000 feet in thickness. 



In this connection it is of interest that in two instances we definitely 

 located the source of certain elements of this micro-fauna by finding 

 a considerable number of specimens actually in situ. The importance 

 of thus locating them may be better appreciated if I explain that 

 perhaps 50 were thus located, whereas 150 others were collected from 



