148 STUART WELLE R 



have so much in common that they may be considered as 

 representatives of a single fauna, yet they may not have been and 

 probably were not strictly contemporaneous. They simply indi- 

 cate that at some stage during the limited time period in which 

 they both belong, there were present in each of these widely 

 separated regions, conditions suitable for the existence of the 

 same general assemblage of species. 



The Chonopectus fauna, which underlies these faunas in the 

 Burlington section, is not represented in southwestern Missouri ; 

 neither is the typical Louisiana limestone fauna present in the 

 region. 



Stuart Weller. 



The University of Chicago. 



