PLATE LIII. 
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Fenestella (Unitrypa) pernodosa. 
Page 139. 
1. A portion of the non-celluliferous face of a frond, natural size. 
2. A portion of another specimen enlarged, showing the irregular nodes. (X 6.) 
3. A similar specimen, with stronger nodes. (X 6.) 
4. A specimen, which has been macerated, showing the striated structure of the branch, beneath the 
surface, on the non-celluliferous side. (X 6.) 
5. An oblique view of two branches of fig. 2, showing the form and arrangement of the nodes. (X 6.) 
6. The celluliferous face of a fragment from which the carinae and scala- have been removed, show¬ 
ing the sinuous form of the branches on this face. (X 15.) 
7. The summits of the carinae with the oblique subtubular openings to the interior of the frond, 
formed by the oblique transverse scalar (X 6.) 
8. A similar view, showing a more irregular arrangement, in which the summits of the carinae are 
not continuous in right lines. (X 6.) 
9. A view of a specimen similar to fig. 7, in which the carinae, scalae and outer portion of the cellu¬ 
liferous test have been removed from the lower half, as shown in the figure, exposing the 
interior of the branches. (X 6.) 
10. The reverse of the preceding, as shown in a natural mould in the rock. (X 6.) 
11. The celluliferous face (if a specimen, showing the structure of the frond ; the lower part of the 
figure shows the celluliferous face with two rows of cell apertures on each branch; above 
this the figure represents the specimen with the celluliferous crust removed, exposing the 
interior of the branches ; the central portion shows the filling of extraneous matter occupying 
the oblique tubes formed by the carinae and scalae which have been removed by solution ; 
in the upper right-hand portion of the figure, the summits of the carinae and scalae are repre¬ 
sented. (X 6.) 
Upper Helderberg group. Walpole, Ontario, Canada. 
Fenestella (Unitrypa) elegantissima. 
Page 140. 
12. The non-celluliferous face of a fragment, natural size. 
13. An enlargement from the preceding, showing the single row of small nodes on each branch. (X 6.) 
14. The non-celluliferous face of a specimen imbedded in the rock ; the branches have been removed 
from the lower left-hand portion, exposing the bases of the carinae and the under side of the 
scalae. (X 6.) 
15. An oblique view of two branches, showing the elevation of the nodes. (X 6.) 
If. The celluliferous face of the branches with the carinae and scalae removed. (X 8.) 
17. The celluliferous aspect of a fragment. The principal part of the figure shows the summits of 
the carinae and the scalae, leaving tubular openings into the interior. On the upper portion of 
the figure the carinae are removed, exposing the celluliferous face of the branches. (X 6.) 
Upper Helderberg group. Walpole, OntaHo, Canada. 
