io8 STUART WELLER 



The Northern Kinderhook fauna. — North and west of the Kanka- 

 kee peninsula, in the eastern portion of the Devonian Interior Conti- 

 nental Province, the earliest Mississippian faunas were as distinctly 

 different from those of the southern portion of the Eastern Continental 

 Province, as had been the preceding Devonian faunas. The oldest of 

 these northern Kinderhook faunas is that of the Chonopectus sand- 

 stone' at Burlington, la., and elsewhere in Iowa and Illinois. This 

 fauna contains a large Devonian derivative element, especially among 

 the pelecypods, but its relationships are with the Chemung faunas of 

 the Upper Devonian, and are totally different from the Devonian 

 derivatives of the southern fauna. Another modification of the north- 

 ern Kinderhook fauna is found in the Louisiana limestone, which is 

 believed to be in part contemporaneous with, and in part younger than, 

 the Chonopectus fauna. One of the most characteristic members of 

 this northern Kinderhook fauna is the striated rhynchonelloid genus 

 Paraphorhynchus which occurs also in the early Mississippian faunas 

 of northwestern Pennsylvania. 



In the Burlington, la., section the Chonopectus fauna occurs at the 

 summit of a series of shales, becoming arenaceous above where the 

 fauna occurs, which have a total depth of i6o feet. The lower loo 

 feet of the formation lies beneath the level of the Mississippi River, so 

 that the contact with the underlying formation and the age of the 

 subjacent bed is not known. This lower bed, however, is probably 

 Devonian, and is not unlikely the Cedar Valley limestone, since that 

 formation lies unconformably beneath the Kinderhook beds farther 

 south in Calhoun County, 111. If this is the case then these lower 

 shales of the Kinderhook correspond in position with the Sweetland 

 Creek shales of the Upper Devonian in Muscatine County, la. There 

 is, however, perhaps insufficient faunal evidence upon which to base 

 a definite correlation of these two shale formations. The most con- 

 spicuous faunal character of the Sweetland Creek beds is the presence 

 of numerous Ptyctodus teeth in the basal bed, occupying a few inches 

 above the unconformity. A similar Ptyctodus bed occurs not infre- 

 quently at the base of the Kinderhook in both the northern and south- 

 ern provinces. Such is the case at the base of the Louisiana limestone 

 at Louisiana, Mo., where Ptyctodus occurs abundantly in a thin shale 



I Weller, Trans. St. Louis Acad. Sci., X, 57-129; also Jour. Geol., XIII, 617-34 



