BRACHIOPODA. 



275 



CO 



50 



s 



5^ -^ 



C ;:ij 



CO 



w 



H 



O 



a 



CTQ 



g o 



M 

 T, 





o 



?3 







35 



o 



to 

 Si 



d 



W 



a* 



Lower Cambiiim. 



MicMlo Cambrijin, 



llpptn- (lunibriaii. 



Caloil'erous. 



Cliazy. 



Trenton. 



Utica. 



Hud'-oii River. 



Niagara. 



Lower Helderberg'. 



Oriidkany. 



Upper Ilelilc-rberg:. 



ILimiltoii, 



(Jlieniuufj,-. 



WavHiIy. 



BurliTi,t>^toii. 



Keokuk. 



St. L.mis. 



Knskaskia, 

 Chester, 



I^r. Coal Measures. 



Middle and Upper 

 Coal Measures. 



I'ennian. 



Triassic. 



