PLATE XLVII. 
Fenestella lunulata. 
Page 121. 
Fig-. 1. An enlargement of a portion of the non-celluliferous face of a frond ; the dissepiments are broad, 
curved and somewhat elevated above the branches, giving to the surface a peculiar appear¬ 
ance. The nodes upon the upper margins of the dissepiments are but moderately developed. 
(X 6.) 
Fig. 2. An enlargement of a portion of the non-celluliferous face of a frond ; the branches and dissepi¬ 
ments are flattened from maceration. (X 6.) 
Fig. 3. An enlargement of a portion of the non-celluliferous side of a frond ; the dissepiments and their 
nodes being so prominent as to in a measure obscure the branches. (X 6.) 
Fig. 4. An enlargement of a portion of the non-celluliferous face of a frond ; the crescentiform elevations 
on the dissepiments, and the more slender nodes on their upper margins. (X 6.) 
Fig. 5. An enlargement of the expanded summits of the carinae. (X 6.) 
Fig. 6. An enlargement of a portion of the celluliferous face of a frond ; the carinae, having been removed, 
showing the form and arrangement of the cell apertures. (X t>.) 
Figs. 7, 8, 9. Transverse sections of branches from different specimens, showing considerable variation in 
the comparative height and width. 
Fig. 10. An enlargement of a lateral view of a branch, showing transverse section of oblique dissepiments, 
the height of the carina, and the cell apertures. (X 6-) 
Upper Helderberg group. Falls of the Ohio river. 
Fenestella serrata. 
Page 110. 
'Fig. 11. An enlargement of a portion of the non-celluliferous face of a frond, having comparatively large, 
quadrangular fenestrules, slender dissepiments, and strong, spiniform nodes on the branches. 
(X 6.) 
Fig. 12. An enlargement of a portion of the non-celluliferous face of another specimen, having smaller, 
more oval fenestrules, and comparatively much stronger branches, without nodes, though this 
may in a measure be due to maceration. 
Fig. 13. An enlargement of a portion of the non-celluliferous side of a frond, having subangular fenestrules 
wider than the branches, the latter having numerous granules or small nodes, which are much 
less conspicuous than those shown in tig 11. 
Fig. 14. An enlargement of a portion of the non-celluliferous face of a frond ; the fenestrules are narrower 
than in figs. 11 and 13, the nodes numerous and more prominent than in tig. 13, though not as 
much so as in fig. 11. (X 8.) 
Fig. 15. An enlargement of a portion of the celluliferous side of a frond, showing angular branches and 
the cells opening laterally, with the branches and dissepiments sharply angular. (X 6-) 
Fig. 16. A lateral view of a branch enlarged, showing transverse section of dissepiments, cell apertures 
and nodes. (X 6.) 
Fig. 17. An oblique view of a portion of the celluliferous face of a frond enlarged, showing the serrated 
appearance of the summits of the branches. (X 6.) 
Fig. 18. A transverse section of the branches. (X 6.) 
Fig. 19. An enlargement of a portion of the non-celluliferous surface of a frond, referred with doubt to 
this species. (X 6.) 
Upper Helderberg group. Falls of the Ohio river. 
