Welter — Kinderhook Faunal Studies. 211 



Yellowstone. Burlington. 



Productus parviformis Productus parvus 



Cleiolhyris crassicardinalis Cleiothyris hirsuta 



Spirifer cenlronatus Spirifer centronatus 



Spirifer marionensis Spirifer marionensis 



Reticularia cooperensis Reticularia cooperensis 



Straparollus utahensis Straparollus oblusus 



There is little or nothing in common between the Chono 

 pectus fauna at Burlington and the fauna described by Girty. 



That the Madison limestone represents a time period much 

 longer than the Chouteau zone of the Kinderhook, seems to 

 be well assured, in fact it is probably the stratigraphic equiv- 

 alent of all the formations in the Mississippi Valley from 

 the Kinderhook at least up to the St. Louis limestone. In this 

 connection it is of interest to note that in the Chouteau fauna 

 and more especially in the fauna of the oolite bed at Burling- 

 ton, there is also an element suggestive of faunas younger 

 than the Osage. Specimens of Cleiothyris hirsuta not dis- 

 tinguishable from specimens of the same species in the 

 Spergen Hill fauna of St. Louis age are present in the oolite 

 fauna at Burlington. Concardium pulchellus has a Spergen 

 Hill representative in C. meekanum, Athyris crassicardinalis 

 is similar to and is perhaps identical with Oentronella crassi- 

 cardinalis, and the particular variety of Rhipidomella burling- 

 tonensis present in the oolite bed at Burlington is represented 

 by R. dubia in the Spergen Hill fauna. 



The suggestion offered as an interpretation of all these 

 various faunal relationships is that after the wide geographic 

 distribution of the later Kinderhook faunas, from Ohio to 

 beyond the Rocky Mountains, there was a withdrawal of the 

 fauna for some reason, within the more western portion of the 

 area it had occupied, where it continued to flourish during the 

 period of development of the Osage faunas in the Mississippi 

 Valley. At a much later period, the beginning of Genevieve 

 time, this western fauna again migrated eastward and entered 

 into the fauna of the St. Louis limestone and its stratigraphic 

 equivalents. The recurrence, in rocks of the age of the St. 

 Louis limestone at Batesville, Arkansas, of a fauna of much 



