DEVONIAN AND MISSISSIPPI AN FAUNAS ill 



although it had its beginnings in the preceding Kinderhook. No local- 

 ity in the world, so far as known, has furnished so large a number of 

 crinoids of similar age, either in genera, species, or individuals, as 

 this Mississippian province. The fauna, in its entirety, exhibits much 

 in common with the mountain limestone of England, Ireland, and 

 elsewhere in Europe. Many species of brachiopods in the formations 

 either are identical or are so closely alHed as to be difficult of separa- 

 tion, and the correlation of the Osage with the Mountain Limestone 

 of England, or at least of some part of it, is based upon substantial 

 evidence. Evidence sustaining the indigenous character of the cri- 

 noidal element in the fauna is found in a comparison of these forms 

 from the Osage of the Mississippi Basin and from the Mountain 

 Limestone of Europe. Every genus in the Mountain Limestone 

 occurs also in the American faunas, while there are many genera which 

 do not occur outside of the Mississippi Basin; furthermore, all of 

 those genera which occur in both this Mississippian province and in 

 Europe are represented by a larger number of species in America. 

 These facts seem to indicate that the Mississippi Valley Basin was the 

 metropolis for this great crinoidal fauna. 



During this period the Cincinnati arch was above sea level, and 

 from this island clastic sediments were being deposited off its western 

 and southwestern shore, which constitute, in part at least, the Knob- 

 stone formations of Indiana and Kentucky, ahhough the basal portion 

 of the Knobstone is undoubtedly of Kinderhook age. The faunas 

 associated with these clastic sediments are usually more meager than 

 in the calcareous sediments of the clear seas farther west, and are 

 somewhat different in character; however, they possess much in com- 

 mon as is evidenced by the wonderfully prolific crinoid fauna of the 

 Crawfordsville beds in Indiana. 



The later phases of the Osage sedimentation became more clastic, 

 especially toward the north, doubtless because of the elevation of the 

 land to the north, and in the Keokuk formation numerous shaly 

 layers occur, intercalated between hmestone beds. The shales become 

 more and more dominant until, in the Warsaw formation, shales 

 constitute the major portion of the sedimentation. In the southern 

 portion of the Mississippian Basin this change in sedimentation was 

 less or even not at all effective, since the Warsaw, as a distinct shale 



