1894.] Vertebrate Fossils. 247 
almost all exposures the exact contact is concealed by a tatus 
from the upper beds. In several instances, however, the true 
relations were easily determined and one, which presented 
particularly favorable conditions is represented here in fig. 2. 
It represents a short section of the east side of one of the main 
‘draws’ emptying into the Niobrara river. At this point 
this small water course has cut directly across the bed of a 
similar water course eroded out of the surface of the Loup 
Fork and since filled by the Equus beds. At this same point 
there enters the main ‘draw’ a small tributary from the east, 
and the combined currents of these two water courses, although 
SNN 
X 
entirely dry except immediately after heavy rains, have sufficed 
to keep the actual contact apparent. At lf. appear the nearly 
horizontal Loup Fork strata with their characteristic fossils, 
Aphelops, Aelurodon, Procamelus, Protohippus, Mastodon, etc. 
At eb. the Equus beds are seen resting unconformably upon 
the Loup Fork beds at an angle of about 15° and containing 
fossils characteristic of these beds, Equus, Elephas, Mylodon, 
Canis, etc.; al. represents the recent deposits in the bottom of 
the “draws,” all below the top of this line is imaginary. On 
the opposite side of the main draw the same conditions are 
seen at the bottom, but toward the top the contact is not so 
apparent, since there is on this side no tributary to aid in 
keeping the exposure free from talus. 
The figures in the plates and the text accompanying this 
paper were executed by Mr. Rudolph Weber. To the various 
members of the expedition, whose liberality made it possible, 
the authors best thanks are especially due. 
