BRACHIOPODA. 



336fl 



sr. 5 



^ 



3 



I I 



t-l 



o 



o 



o 



CD 



Lower Cambrian. 



MuMlc Cambrian. 



Upper C:iini)ri;in. 



Calciferous. 



Chazy. 



Trenton. 



Utica. 



Hudson River. 



Clinton. 



Niagara. 



Lower lleUIerber^^. 



Oriskauy. 



Upper Helderberg. 



Hamilton. 



Chemung. 



Waverly. 



Burlinffton. 



Keokuk, 



St. Louis. 



Kaskaskia, 

 Chester. 



Lr. Coal Measures. 



Middle and Upper 

 Coal Measures. 



Permian. 

 Triassio, 



