io6 STUART MUELLER 



the Rocky Mountain Basin. The Western Continental Province 

 remained much as in Devonian time, faunally isolated to a great 

 extent from the interior province. The Eastern Border Province was 

 even more isolated, its faunal history, so far as known, having no 

 points of contact with the interior. 



The more complete and differentiated faunal history of the Missis- 

 sippian is that of the Mississippi Valley Basin which will be used as 

 a standard of comparison for the other provinces or subprovinces 

 considered. 



THE MISSISSIPPI VALLEY BASIN 



The Southern Kinderhook fauna. — When the Upper Devonian or 

 New Albany black shale is well developed in southern Indiana and 

 Illinois, the initial Kinderhook bed, the Rockford limestone, follows 

 it with no stratigraphic break. In following the Kinderhook beds to 

 the north, however, they are found to succeed, unconformably, forma- 

 tions of much greater age. The same condition also probably holds 

 in passing from Burlington, la., to the south, although the transition 

 beds from the Devonian to the Kinderhook are not exposed in the 

 Burlington section. An actual land barrier, the Kankakee axis of 

 Schuchert, separated these northern and southern basins at the begin- 

 ning of Kinderhook time, when each basin was occupied by its own 

 distinctive and characteristic fauna. Before the close of the Kinder- 

 hook this barrier was submerged and a common fauna occupied the 

 entire Mississippi Valley Basin. 



The fauna of the Rockford limestone contains new elements which 

 were unknown in the preceding Devonian faunas, associated with 

 certain other forms which are clearly Devonian derivatives. The typi- 

 cal expression of this more southern type of the Kinderhook fauna, 

 however, is found in the Chouteau limestone of central and southern 

 Missouri and Illinois, although there are several modifications of the 

 fauna in the various more or less local formational units of the Kinder- 

 hook of this region. Among other things the fauna contains numerous 

 goniatites, some of which are notable forms and have no relationships 

 vnth any of our known Devonian goniatites. Aganides rotatorius, 

 from the Rockford goniatite bed of Indiana, is identical with a form 

 in the basal Mississippian beds of Belgium and Ireland. Associated 



