II 



are also found along the Bitter Root. Prof. p]lr()»l says they are still 

 l>laiuer iu the roKion of Flathead Lake. These lines are always level 

 and keep at the same altitude along mountains of hard (inartzyte and 

 hills of loose gravel. It is difficult to see how these lines can be pre- 

 served so long where the material is soft and iiicohciciit ; and one is 

 led to believe that the water cut with comparative rapidity through 

 its barrier iu geologically recent times. When the water reached its 

 highest point it remained for a long time at or near the same level. 

 Prof. Bailey Willis of the U. S. Greological Survey who has visited this 

 region suggests the idea that this was a Pleistocene lake dammed by a 

 glacier. In the Missoula valley are soft laminated clays quite different 

 in appearance from these from which fossil bones were found. 



The lake beds lie in contact with all the older formations that 

 Occur In the western part of the state— the Archaeon, Algonkian, Cam- 

 brian, Devonian, Triassic, Jurassic, and Cretaceous.* Tbe newer beds 

 lie unconformalvly on the older— at least in many places— and in the 

 interval between the deposition of the two the White River beds 

 were tilted and carved into hills and benches and valleys, and the 

 waters covered them again, after nearly all vertebrate life had 

 changed, and a new deposit was made with remains of a later fauna 

 entombed in it. 



The most of the remains found are mammals and turtles, though 

 there are a few fragments of bird bones, representing two or three 

 species. Many snails and a few clams have been collected but have 

 not been determined. 



I have had time to study and describe only a small portion of 

 my collection, and then under circumstances not the most favorable; 

 though the young and growing University of Montana has done all it 

 could to help me. It has been my effort to make as few mistakes as 

 possible, yet, as circumstances have compelled me to work alone, iso- 

 lated from other collections and libraries complete with the literature 

 needed, it is impossible that no mistakes should be made. So I ask 

 the kind indulgence of those older in the work and more favorably 

 situated. I think it better to do the ])est I can than to leave other 

 workers in perfect Ignorance of what is found here. 



It could hardly be expected that in the formation with fossils so 

 much resembling the Loup Fork of Nebraska there should be so 

 many new species as I have described. I have described none how- 

 ever that I could classify witli the species already found; though it 

 if! sometimes difficult to settle the matter by the short descriptions and 



* For general iiistory of these lake basins see Livingston and 

 Three Forks folios of the V. S. Geological Survey. 



