XV. FOSSIL HORSES FROM NORTH DAKOTA AND 



MONTANA. 



By Earl Douglass. 



Until recently, there has been no opportunity to study the fossil 

 horses which have been obtained in Montana and North Dakota for 

 the Carnegie Museum. At the request of Dr. W. J. Holland, the 

 director of the museum, a preliminary account of some of the more in- 

 teresting of these remains has been prepared. When all the material from 

 these regions has been thoroughly studied and compared with that 

 from other localities, much will be added to our knowledge of the 

 history of the fossil horses. 



In 1905, the expeditions from the Carnegie Museum which had 

 previously confined their operations to western Montana, extended 

 them into parts of Minnesota, Idaho, and North Dakota. In the last 

 mentioned state, the deposits which probably were visited by Professor 

 E. D. Cope, 1 in 1883, were searched for fossil mammals. In the 

 "Little Bad Lands" southwest of Dickinson, another area of Oligo- 

 cene deposits was discovered. In both localities the three divisions 

 of the White River (lower, middle, and upper) are exposed, and 

 from the middle and upper horizons many fossil mammals were 

 obtained. 



The White River beds of North Dakota and their mammalian faunae 

 are much like those of South Dakota, though there are some local dif- 

 ferences. On the other hand the various Tertiary deposits of western 

 Montana do not exactly agree in character with those of the plains. 

 As one by one the families of fossil mammals from the Tertiary 

 horizons of Montana have been studied, it has been found that most 

 of the species and part of the genera are different from those which 

 have been obtained elsewhere. It might have been suspected that 

 the camels and horses were more cosmopolitan than some of the other 

 animals, and that identical species would be found in beds which 

 were supposed to be nearly or quite contemporaneous in the moun- 

 tains and on the plains. In the present paper, I have included pro- 

 visionally under old names, some species which I believe will eventually 



1 Proc. Amer. Philos. Soc, Vol. XXI, p. 216. 



267 



