22 Annals of the Carnegie Museum. 



paper be alluded to only when necessary to do so in the interests of 

 perspicuity. 



In 1902 Mr. J. B. Hatcher 2 subdivided these beds and mentioned 

 a number of species belonging to their faunae. While the subdivisions 

 which Hatcher proposed are here followed in the main, it may be 

 stated that the horizons determined by him are difficult to distinguish 

 on account of their lithological similarity. This is especially true of 

 the Gering and Monroe Creek beds. In Fig. 1 each horizon is denned 

 far more clearly than in nature in order to -make the subject plain to 

 the reader. The species given by Hatcher (/. c, p. 117) in one or 

 two cases are incorrectly identified. 3 



Referring to Fig. 1 attention should be called to the fact that the 

 upper fifty or sixty feet of Squaw Butte appear to represent the Harri- 

 son beds. The Monroe Creek beds, however, run insensibly into the 

 latter and the dividing line is difficult to determine except for the fact 

 that Dcemonelix, which is characteristic of the Harrison beds, occurs 

 in the upper strata. Along the line of the section Niobrara River 

 (locally known as the "Running-water") does not cut through the 

 Harrison beds, and the thickness of the Monroe Creek beds and the 

 Gering horizons are here only conjectural. The sedimentary mass 

 apparently decreases in thickness southward and eastward, so that if 

 the lower horizons (Monroe Creek beds and Gering beds) are present 

 at this point they are probably quite thin. 



The sandhill region, south of the Niobrara River, represented in the 

 illustration is a narrow strip extending east and west. The deposit is 

 of late origin and has the usual seolian character met with in the more 

 extensive sandhill areas further east in the State of Nebrasba. This 

 deposit rests unconformably on the Harrison and the Upper Harrison 

 (Nebraska 3,1 ) beds. 



Spoon Butte is located in the southwestern part of Sioux County, 

 Nebraska. It is a long and narrow elevation with deeply eroded sides 

 and a flat top. The long axis of the butte is directed nearly east and 



2 Proc. Am. Phil. Society, Vol. XLL, pp. 113-131, 1902. 



3 Hatcher wrongly identified Protolabis for Oxydactylus, and Cyclopidius for Mery- 

 chyns. No Cyclopidius has as yet been found in the Upper Harrison beds. 



3a From a verbal statement made recently by Professor H. F. Osborn it now ap- 

 pears that the beds which Professor W. B. Scott referred to the Nebraska beds are of 

 later origin than those, which, in former papers, I have referred to that horizon. 

 This horizon, therefore, may be called the Upper Harrison beds and in this paper will 

 be referred to under that name. 



