468 Trans. Acad. Sci. of St. Louis. 



the fauna as a whole, each one of the two factors in the fauna 

 havino- a geographic distribution different from the other. 

 Such a study further shows that in early Kinderhook time 

 there were two distinct faunal province within the present 

 Mississippi valley region, a northern province and a southern 

 province, separated by an east and west line at a point near 

 the mouth of the present Illinois river. Whether this line 

 of separation was actually a land barrier has not yet been 

 shown, but such was probably the case. 



The history of events in the northern Kinderhook province 

 is most completely shown in the section at Burlington, Iowa. 

 In this section there are approximately 115 feet of strata ex- 

 posed, and in this thickness the lower 100 feet are essentially 

 characterized by one general fauna, the Chonopectus fauna, 

 although there are some faunule variations in the succession 

 of beds exposed. This is the characteristic fauna of the 

 northern Kinderhook province. Besides its occurrence at 

 Burlington, it is known 60 miles northwest of that locality 

 near Wellman, in Washington County, Iowa, where it occurs 

 in its typical expression in the English River grit, at Maples' 

 mill. It probably occurs, also, still further northwest, 120 

 miles from Burlington, in Tama and Marshall counties, in the 

 arenaceous beds beneath the Kinderhook limestones of that 

 region, but the fact of such occurrence has not yet been act- 

 ually confirmed by the writer. South of Burlington the same 

 fauna, somewhat modified but still containing its characteris- 

 tic elements, occurs in the Kinderhook sandstone at Kinder- 

 hook village in Pike county, Illinois, and at this locality there 

 are present in the fauna certain elements that connect it closely 

 with the fauna of the Louisiana limestone. This relationship 

 of the Chonopectus fauna as it is exhibited at Kinderhook, 

 Illinois, is of a nature to show without doubt, that the Louis- 

 iana limestone fauna is but one facies of the general fauna of 

 the northern Kinderhook province. The Louisiana facies of 

 the fauna, in its typical expression, has been recognized as far 

 south as northern Calhoun county, Illinois, where it occurs at 

 Hamburg on the Mississippi river. 



One of the most characteristic elements in the northern 



