lliomsolves out into the large aud deep lakes until a good portion was 

 dry laud or marsh. Then came a period of drainage and erosion wliicli 

 was perhaps as great. As this was repeated, tlie length of time was 

 certainly long enough to make several almost complete cliangcs in 

 the species of higher animals. 



The geological age of the l>eds outside of the Smith river valley 

 has been a matter of doubt; and so far as I have been able to ascertain, 

 few fossils had been collected from them. Hayden aud Peale called all 

 Pliocene without distinction. In the Jefferson valley Hayden dis- 

 covered what I.i'idy called Anchitherium and a species of Helix. * 



Leidy described the former viuder the name Anchitherium agreste.** 

 This I believe to be a Protohippus as I have the lower jaw. with teeth 

 that cannot be distinguished from that described by Leidy. associated 

 with part of the upper jaw and teeth of a Protohippus from near 

 1'ownsend. 



Peale in the Three Forks atlas sheet saj^s: "In the summit of the 

 Madison bluffs, in a layer of gray conglomerate sandstone numerous 

 fragments of fossil bones were found, which were identified as the 

 same as were found iu other localities in the Pliohippus beds of 

 Marsh." 



In no place have I found fossils abundant, yet there has been 

 enough to arouse and sustain the most lively interest. No great quan- 

 tity of any one species was found and the collection presents a large 

 number of species in proportion to the amount of material. 



Besides the bones mentioned by Peale, teeth and jaws of two o^ 

 three mastodons and a skull of Procamelus were found by ranchmen, 

 but so far as I know they have been preserved only as curiosities. The 

 Procamelus skull was purchased, and it is now in my collection. 



I give on the next page a table showing succession of strata as ex- 

 posed on the lower Madison, with list of the fossils, so far as have 

 been determined, that have been obtained at this place, and from 

 the same horizon in other localities in the state. 



There Is a considerable difference in species between the Loup 

 Fork of this region and that of other localities, but the difference is 

 probably one of locality rather than age. There was. I judge, as great 

 a difference in the animal life between this mountain region and the 

 region east of it as there is to-day. Prol>ably the Montana species 

 more resembled those found near Cottonwood creek in Oregon. Al- 

 though the material has not been fully worked up. there are some 

 species that are especially interesting as they show the close relation- 

 ship between the fauna of this country and that of the corresponding 



* Sixth Ann. Rep. T'. S. Oeol. Sur. Tei-r.. p. 65. 

 ♦♦Monograph I. I^ S. (ieol. Rur. Terr., p. 2r.L Plate XVIT. 



