314 STUART WELLER 



that rapid and relatively violent local changes were in progress 

 throughout this whole period of readjustment. 



The fauna of the Ste. Genevieve epoch in all its varied phases 

 is but imperfectly known, but it apparently contains, throughout, 

 in greater or less degree, the western element suggestive of the 

 prolonged Devonian, which first makes its appearance in the St. 

 Louis limestone fauna, and continues on even into the faunas of 

 the Coal Measures. 



In the geologic history of our continent during Mississip- 

 pian time, many details remain to be elaborated, and with the 

 elaboration of these details our conception of it may be altered 

 in some respects. It is believed, however, that further investi- 

 gation will but make clearer the general features as outlined 

 here. The threefold classification of the Mississippian strata, 

 based upon the actual geologic history of the region as told by 

 the fossils and by the geographic evolution, is seemingly the 

 only natural one. 



An attempt has recently been made 1 to substitute the name 

 Augusta for Osage. The two names have been proposed for 

 practically the same stratigraphic series, but in their proposal 

 the two authors seem to hold very different conceptions of the 

 criteria which should be used when the classification rises above 

 the mere grouping of beds of a local character. The name 

 Osage was proposed for a definitely recognized chapter in the 

 geologic history of the region under consideration, while 

 Augusta was proposed as the name of a special stratigraphic 

 division composed of certain local formations. Hair-splitting 

 distinctions between the exact limitations of groups of beds — 

 however necessary in local and minor classifications — can have 

 no decisive weight in the case, when the higher purpose of 

 major classification, as an expression of the vital features of the 

 history of the region, are duly considered. 



Stuart Weller. 



The University of Chicago. 



1 Am. Geo!., XXI, p. 229. 



