PLATE LI. 



Fbnestella (Unitryta) AOAULIS. 



Page 131. 



V\g. I. The celluliferotis face of a specimen, natural size, showing the summits of the carinse and scalse. 



Fig. 2. A portion of the non-celluliferous face of the preceding. (X 6.) 



Fig. 3. A jwrtion of the non-cellulifei-ous face of another specimen, showing more slender branches. 



(X6.) 

 Kig. 4. A lateral view of a branch, showing the cell apertui-es, minute pits in the base of the carina, and 



a transverse section of the lamelliform connecting bars, or scalse. 

 Fig. 5. The celluliferous side of a fragment, fi-om which the carinsR and scalie have been i-emoved, show- 

 ing two rows of cell apertui-es on each branch. (X 6.) 

 Fig. 6. An enlargement, to six diameters, of fig. 1, showing more distinctly the character of the summits 

 of the carinfle and seals. 



Upper Helderberg group. FbUs of the Ohio river. 



FbNKSTBLLA (UnITRYPA) 8T1PATA. 

 Page 134. 

 The non-celluliferous face of a fragment, natural size. 



A portion of the preceding, showing the angular branches and irregular fenestrules. (X 6.) 

 The non-cellulifei-ous face of another fragment, natural size. 



A portion of the same, showing smaller fenestrules than the preceding specimen. (X 6.) 

 The celluliferouR face of a fragment from which the carinse and scalie have been removed. The 

 branch at the left of the figure shows the natural condition of the cell apertures ; on the two 

 adjacent branches the margins of the apertures are thickened and the opSTiings closed ; the 

 next branch shows the margins broken away, and in the right hand branch the entire upper 

 test has been removed, showing the interior of the cells. 

 Fig. VI. A fragment, natural size, showing the summits of the carinee and scalse. 

 Fig. 13. A portion of the same. (X 6.) 



Rg. 14. A transvei-se section, showing the form of the branches, the height of the carinte and the extent 

 of the scalse. 



Upper Helderberg group. Falls of the Ohio river. 



Fenestblla (Unitkypa) TEGULATA. 



Page 13JS. 

 Fig. 15. A portion of the non-celluliferous face of a specimen. (X 6.) 

 Fig. 16. The non-celluliferous face of another specimen, showing a marked contrast with the preceding, 



in its irregular angular branches and fenestrules. (X 6.) 

 Fig. 17. The celluliferous face of fig. 15, with the carinse and processes removed ; the right-hand branch 



has the tissue broken away, showing the interior. (X 6.) 

 Fig. 18. The celluliferous face of the same, natural size, showing summits of the carinK and seals. 

 Fig. 19. A portion of the same, enlarged, showing more distinctly the charactei-s of the specimen, fig. 18. 



(X6.) 

 Fig. 20. The summits of the carins with the scalte, from the celluliferous face of fig. IK. (X 6.) 

 Fig. 21. A transverse section, from the specimen fig. 15, showing the form of the branches, the elevation 



of the carinse and the extent of the scalar. (X 6.) 

 Fig. 22. A lateral view of a branch, natural size. 



Fig. 23. A ix)rtion of the same enlarged, showing the direction of the lamelliform scalip. (X 6.) 

 Upper Helderberg group. Falls of the Ohio river. 



