PLATi) 12. 



Fenestella (Polypoea) fistulata. 



Figs. 1-16. 



Fenestella (Polypora) fistulata, Hall. Eeport of State Geologist tot 



1886, page 64. 

 Fig. 1. A fragment of the celluliferous face, natural size. 

 Fig. 2. A fragment of the non-celluliferous face, natural size. 

 Fig. 3. An enlargement, showing straight, regular, angular branches and 



dissepiments. 6 x. 

 Fig. 4. An enlargement, showing more slender, rounded branches and 



dissepiments. 

 Fig. 5. Enlargements from different portions of the same frond, one por- 

 tion showing very strong regular branches, the other portion 



more slender, sinuous branches. 6 x. 

 Fig. 6. An enlargement, showing flattened branches with a carina along 



the middle. 6 x. 

 Fig. 7. An enlargement from a frond partially covered by a rock deposit, 



causing the branches to appear very slender. 6 x. 

 Fig. 8. An enlargement, showing slender branches and very nearly circu- 

 lar fenestrules. 6 x. 

 Fig. 9. An enlargement, showing somewhat irregular branches connected 



by very slender branches. 6 x. 

 Fig. 10. An enlargement, showing decidedly angular carinated branches 



and dissepiments. 6 x. 

 Fig. 11. An enlargement from the celluliferous face, showing the narrow 



fenestrules, wide branches, and form and disposition of the cell 



apertures. 6 x. 

 Fig. 12. A still further enlargement, showing more distinctly the form of 



the cell apertures. 18 x. 

 Fig. 13. An enlargement of a portion of a branch having only two ranges 



of cell apertures. 18 x. 

 Fig. 14. A lateral view of a portion of a branch. 18 x. 

 Fig. 15. A further enlargement of the preceding, showing the form of the 



branches and the thickness of the dissepiments. 18 x. 

 Fig. 16. A transverse section of a frond. 6 x. 



