358 Trans. Acad. Sci. of St. Louis. 



were soon assigned altogether to the Devonian, then all were 

 a^ain transferred back to the Carboniferous, where, by com- 

 mon consent, and in the absence of further direct inquiry, they 

 long remained. But accumulated evidence now indicates that 

 their proper place lies partly in the older of the two systems 

 and partly in the younger. However, the grounds for this 

 return in large part to the earliest definitely expressed view 

 are very different from those which were adopted in the be- 

 ginning. Curiously enough, while the reasons for their early 

 reference to the Devonian were found of late years to be 

 entirely erroneous, the first conclusions were in fact prac- 

 tically correct for the particular district under consideration 

 along the Mississippi river; the premises were totally wrong, 

 and the decisions were founded upon faulty correlations. 

 Herein lies the confusion which has so long existed regarding 

 the proper position of the beds. 



The history of the various changes and correlations of the 

 beds under consideration would be a long and perhaps some- 

 what tedious account, but there is no need of entering into its 

 complications in the present connection, as the main features 

 have been so lately* summarized. 



Since the appearance of these summaries special work f in 

 the region has led to considerable modification of some of 

 the views there expressed. At the localities from which the 

 leading fossil forms had been described it was found that the 

 horizon from which they had come was beneath the Louisiana 

 or the " Lithographic " limestone, the commonly recognized 

 basal member of the Kinderhook. 



Still more recently a careful examination of the Litho- 

 graphic beds has been made with the special object in view of 

 discovering fossils in the seemingly unfossiliferous layers 

 above the base, and of determining the vertical distribution 

 of the organic remains. The locality selected was Louisiana, 

 in Pike County, Missouri, where the exposures were unusually 

 favorable, where the vertical section was complete from the 



* U. S. Geol. Sur., Bull. 80, pp. 146-170, 1891: also Bull. Geol. Soc. 

 America, vol. in. pp. 283-300, 1894. 



t Missouri Geol. Sur., vol. iv. pp. 54-55, 1894. 



