\J 



PLATE 21. 



Favosites baculus, Nov. Spec. Devonian. 



1. 2. 3. Lateral views of three several coralla from the Lower Devonian, 

 Falls of the Ohio. Zaphrentis exigua, it will be remarked, is 

 attached to the matrix in which example 3 is imbedded. Collec- 

 tion of the author. 



4. Longitudinal section of the upper portion of a small corallum from 



the same horizon and place. Collection of the author. 



Favosites digitatus. Devonian. 



5. Portion of a corallum from the dark red clay of the encrinal lime- 



stone underlying the shale which separates the Devonian and 

 Sub-carboniferous formations, near Louisville. Collection of the 

 author. 



