BEEDE AND ROGERS.| Coal Measures Faunal Studies. 835 
Oklahoma are great thicknesses of rocks referable to the Coal 
Measures which underlie the “‘Lower Coal Measures” of Kan- 
sas, so that, in a broad sense, our Lower Coal Measures may 
turn out to be the basal part of the Upper Coal Measures or the 
top part of the Lower Coal Measures. 
A eareful inspection of the charts shows that they fall into 
groups which mark off salient periods in the geologic history 
of the region. The faunal assemblages are distinctive when 
studied with respect to the relative abundance of their species 
and the part they play in the older and younger formations, to- 
gether with the introduction of new species and the disap- 
pearance of old ones. 
One other feature is of interest here, and that is that when 
an influx of new species is noted in any limestone there is fre- 
quently a final disappearance of some of the older residents of 
the region after passing that particular limestone. The Iola 
limestone is a good example of this condition of things, which 
tends to complicate the establishment of sharp division lines. 
As a result of the study of the fauna as a whole the following 
larger and smaller faunal divisions have been made out. 
In order to show the relation of this classification to the 
purely stratigraphic (or, better, physiographic) one employed 
by this Survey and classifications used by other organizations 
and individuals we give the following tabulation. 
