I 



238 



DOUGLASS — FOSSTL MAMMALIA 



under the name of Merycochcerus laticeps (1900) ; but since seeing the skulls of this 

 genus in the American Museum of Natural History, I am inclined to think it will have 

 to be given a new generic name. Both of these are vastly different from the John Day 

 forms, Promerycochierus, that have been put in this genus. 



The beds underlying these look like some of the Oligocene east of the main divide. 

 They are light colored. There are layers of limestone containing fresh-water snails. In 

 one place there were thinly laminated shales with a few fish remains. 



A few miles to the northeast, on the north side of the Hell Gate river, in gray sandy 

 bluffs, the skulls of a dog much like Temnocyon, a Leptomeryx, and an Oreodont were 

 discovered. These beds may be John Day. 



Before going to a new field Prof. Smith was called away and Mr. Homer McDonald, 

 a student of the University, accompanied me during the remainder of the time. After 

 obtaining a few remains of a large rhinoceros, a large camel, and some poorly preserved 

 mastodon teeth from the later Tertiary in the Deer Lodge valley, we crossed the divide 

 southwest of Butte. 



Near Whitehall, at two localities on Pipestone creek, one near Pipestone Springs and 

 one on a, branch called the Little Pipestone, were limited exposures where many small 

 bones, teeth, and fragments of jaws were found. These were associated with distinguish- 

 able Titanotherium remains which were not of the largest species. 



After making a, valuable collection here we moved eastward, examining the Tertiary 

 deposits on the North Boulder and obtaining jaws and teeth of a Protohippus. 



Northwest of Three Forks are gray beds composed of fine material containing lime 

 and looking much like the beds on Pipestone creek. Then! are also layers of hard lime- 

 stone which break into angular fragments. Here there were a good many Titanotherium 

 remains. We obtained large parts of two skeletons and other bones. Some interesting 

 little Oreodonts, including a, little Agrioehoerm, were obtained, descriptions of which will 

 be found in this paper. 



Last spring (dune, 1900) I again started from Missoula, going up the Big Blackfoot 

 river, hoping to find Tertiary deposits on this river or on Nevada creek, one of its prin- 

 cipal branches. The country around Ovando is covered with glacial drift, but on the 

 road from that place to Helmville, near where it crosses the Big Blackfoot, the drift 

 becomes thin and finally vanishes. The river cuts into the Tertiary deposits, in some 

 places making quite high bluffs. I found no fossils here except wood fragments, but tins 

 beds are undoubtedly Oligocene (White River or John Day). After passing through a 

 quite long canon in going southeast up Nevada, creek, the Tertiary appears again. The 

 rock is mostly soft, but in places thousands of flint fragments have weathered out and are 

 scattered over the surface. In some of these there are fossil snails. A few miles north of 



