PLATE XIX. 



Fenestella (Poi.yi'ora) stricta. 



PajfO 5». 

 Fig. 1. A fragment of a frond, natural size. 



Lower Helderberg group. Clark.iville, N. Y. 

 Vig. 2. An enlargement of the non-celluliferous face of the preceding. 



Fene-stella (Polypora) Eudora. 



Page 6fl. 

 Fig. 3. A fragment of the non-celluliferous face of a frond, natural size. 

 Fig. 4. An enlargement of the preceding. 

 Fig. 6. An enlargement of the cellulifennis face of a frond, referred to this species with doubt. 



Lower Helderberg gi-oup. ClarksvUle, N. Y. 

 Fig. 6. A fragment of the non-celluliferous face of the frond. 



Pig. 7. An enlargement of the celluliferous face of the pi-eceding, showing smaller cell apertures, which 

 are in some parts more numerous. 



Lower Helderberg group. Clarksvitle, N. Y. 

 Fig. 8. A fragment of the non-celluliferous face of a specimen. 

 Fig. 9. An enlargement from the cellulifei-ous face of the preceding, showing more elongate fenestrules 



than the above forms. 

 Fig. 10. An enlargement of the non-celluliferous face of the specimen fig. 8. 



Fenestella ^syle. 



I'agc 46. 

 Fig. 11. A portion of the frond, natural size, showing the non-celluliferous face. 

 Fig. 12. An enlargement of the non-celluliferous face, from the preceding. 



Lower Helderberg group. New Salem, N. Y. 

 Fig. 13. An enlargement of the non-celluliferous face of another specimen, showing more slender branches 

 and wider fenestrules. 



Fenestella (Polypora) Tdothea. 



Fig. 14. A portion of a frond, natural size, showing the celluliferous face. 



Lower Helderberg group. Clarksville, N. Y. 

 Fig. 15. An enlargement from the preceding. 



Fenestella Spio. 



Pago 47. 

 Fig. 16. A portion of the celluliferous face of a frond, enlarged. 

 Lower Helderberg group. Clarksville, N. Y. 



Fenestella Althaea. 



Page 48. 

 Fig. 17. An enlargement of the non-celluliferous face of two fragments a and b, which are probably pai-ts 

 of the same frond. 



Lower Helderberg group. ClarksinlU, N. Y. 

 Fig. 18. An enlargement of the non-celluliferous face of another specimen, showing larger fenestrules. 



Lower Helderberg group. Clarksville, N. Y. 



Fig. 19. An enlargement of the non-celluliferous face of a fragment from another fi-ond. 



Lower Helderberg gi-oup. Clarksville, N. Y. 



