PLATE LII. 
Fenestella (Unitrypa) lata. 
Page 136. 
1. An enlargement of a portion of the non-celluliferous face of a frond, showing very regular 
branches and angular carinate dissepiments. (X 6.) 
2. An enlargement having a somewhat more robust appearance than the preceding. (X 6.) 
3. An enlargement; the branches and dissepiments are partially imbedded in a sediment and presents 
a much more slender appearance than Would be the case if the whole surface could be 
observed. Without a careful examination, this would seem to be the full size of the branches 
and dissepiments (X 6.) 
4. An enlargement, representing an impression in the rock ; the left of the illustration represents 
the impression left by the carinae and connecting scalae, the right the impression of the cell 
bases. The tissue has been partially destroyed by maceration; the solid portion left is the 
filling in of the cells and of the spaces between the scalae; the solid oval spaces are the filling 
of the fenestrules. (X 6.) 
5. An enlargement of a portion of the celluliferous face of a frond, showing the form and arrange¬ 
ment of the cell apertures, the carinae having been broken away. (X 6.) 
(3. An enlargement of the summits of the carinae and the scalae connecting them. 
7. An enlargement ; the upper left corner represents the non-celluliferous face of the branches ; the 
remainder of the illustration represents the bases of the carinae, that is, the portion joining the 
celluliferous face of the branches and the under side of the scalae connecting the carinse. The 
entire substance of the cell-bearing portion of the branch has been removed from this portion 
of the specimen. (X 6.) 
8. An enlargement; the upper portion of the figure representing the interior of the branches and 
the exterior with cell apertures ; the lower and left hand portion, the summits of the carinae, 
and the scalae connecting the carinae. (X 6.) 
9. A lateral view of a branch enlarged, showing a transverse section of the dissepiments, and the 
scalae connecting the carinae, which are abruptly bent at a point a little above the middle of 
their depth. (X 6.) 
10. A. fragment, natural size, comprising a portion of the base of a frond. 
Fenestella (Unitrypa) ficticius. 
Page 137. 
11. An enlargement; the lower portion represents the non-celluliferous face of the branches; the 
upper portion the base of the carinae and the under side of the scalae. (X 6.) 
12. An enlargement of a portion of the non-celluliferous face of a frond. (X 0.) 
13. An enlargement of the summits of the carinae and the obliquescalae. (X 6.) 
14. An enlargement of a portion of the celluliferous face of a frond, having the carinae and scalae 
removed, showing the form and arrangement of the cell apertures. (X 6.) 
15. An enlargement of the base of the carinae and the under side of the connecting scalae, similar to 
the upper portion of fig. 11. This illustration is given to show how easily it might, by itself, be 
mistaken for the celluliferous face of some form of Fenestella. (X 6.) 
Upper Helderberg group. Walpole, Ontario, Canada. 
