362 Trans. Acad. Sci. of St. Louis. 



knowledge which has long existed regarding the exact horizons 

 at which the various genera and species occur that the general 

 faunal facies of the " Kinderhook " has therefore borne a 

 composite and not a pure physiognomy. 



A tabular arrangement of all the species of fossils that are 

 recognized at a typical locality for the Kinderhook, and that 

 range from the Silurian to the upper Burlington, has brought 

 out very clearly some important facts which heretofore have 

 been overlooked. The first of these is the close affinity of 

 the faunas from the lower two members of the Kinderhook 

 with the underlying Devonian, and the second is the sharp- 

 ness with which the lower fauna stops at the base of the 

 Chouteau, and the abruptness with which an entirely new 

 fauna begins at the same level. 



2. The components of the lower fauna comprise those 

 forms which, as will be seen hereafter, occur in the Louisiana 

 limestone and the Hannibal shales. For the present only the 

 species from the former need occupy attention. The distri- 

 bution of the forms so far as known is shown in the accom- 

 panying table, the figures at the top corresponding with the 

 numbers of the beds in the ideological section at Louisiana* : — 



* In the preparation of the tables due acknowledgment should be made to 

 Mr. R. R. Rowley. His large collection and long residence in Louisiana 

 enables a degree of completeness to be given them that would otherwise not 

 have been possible. 



