PLATE XXVII 



PAGE 



Figs. 1-6. STROMATOPORA CONSTELLATA Hall 221 



1, 2. Type A. Tangential and radial sections. X 10. Lower Stroma- 

 topora bed, Devil's Backbone. 



3. Type B. Tangential section. X 10. Keyser, W. Va. 



4. Type B. Tangential section. X 10. Cash Valley. 



5. 6. Type C. Tangential and radial sections. X 10. East bank of 



Potomac River opposite Pinto. 

 Helderberg formation, Keyser member. 



