PLATE XLV. 
Fenestella vartapora. 
Page 104. 
See Plate 35. 
1. A portion of a frond near the base, natural size. 
2. An enlargement of the preceding-, showing more distinctly the shape of the frond, the elongate 
supporting processes near the base, the form and comparative size of the branches and dissepi¬ 
ments and the aspect of the fenestrules. (X 6.) 
3. An enlargement of a portion of the celluliferous face of the same frond, showing the form and 
arrangement of the. cell apertures and the occasional large cells immediately below the bifur¬ 
cations. (X 6.) 
4. An enlargement of another portion of the celluliferous face, showing angular and carinated 
branches. The carinse are nodose, the nodes being essentially equal in number to the cell 
apertures. (X ti.) 
5. An enlargement of the celluliferous face of a frond ; the cell apertures are obsolete, with the 
exception of a portion of one branch. (X 6.) 
6. An enlargement of a portion of the celluliferous face of a frond ; the surface of the two branches 
at the left of the figure is worn away showing the interior of the cells ; the remaining branches 
are still more deeply weathered, the cells being entirely worn away and the interior of the 
non-celluliferous portion of the branches exposed. (X <>•) 
7. An enlargement of a portion of a non-celluliferous face of a frond, showing very irregular 
branches, which have a width about equal to that of the dissepiments; the fenestrules vary in 
form from elongate-oval to circular. (X 6.) * 
8. A portion of the non-celluliferous face of a frond, showing the branches much more regularly 
disposed than in the preceding figure. Over the greater portion of the specimen the fen¬ 
estrules are nearly circular. (X 6.) 
9. An enlargement of the celluliferous face of the preceding, showing the form and arrangement of 
the cell apertures and the prominent nodes between the ranges; both the nodes and apertures 
are more closely arranged than on fig. 4. (X 8.) 
10. An enlargement of another portion of the celluliferous face of the same specimen, showing very 
large cell apertures occurring at irregular intervals, but invariably opposite a dissepiment. 
(X 6.) 
11. A lateral view of a branch, showing a transverse section of the dissepiments, the cell apertures 
and the form of the nodes along the middle of a branch. (X 6.) 
12. A lateral view of a branch from another frond where the nodes are obsolete. The dissepiments 
are more nearly circular in section and more distant than in fig. 11. (X 6.) 
13. A portion of the non-celluliferous face of a frond encrusted by other organisms. (X 6.) 
Upper Helderberg group. Falls of the Ohio river. ' 
Fenestella stellata. 
Page 109. 
See Plate 47. 
14. An enlargement of a portion of the non-celluliferous face of a frond. (X 6.) 
15. An enlargement of a portion of the celluliferous face of the preceding, showing the form and 
arrangement of the cell apertures and the strong nodes along the middle of the branches. 
This specimen differs very much in appearance from the usual varieties of the species, but as 
every gradation between the two exfremes occur, there are no means of separation from the 
typical forms. (X 6.) 
Upper Helderberg group. Falls of the Ohio river. 
