104 CANADIAN FOSSILS. 
In this species, the branches are sometimes compressed vertically (or in 
the direction from the celluliferous face to the back of the stipe), to such 
a degree as to give an apparent double serrature, or a celluliferous face. 
on each side. In this condition, the cell-apertures are at right angles to 
the direction of the axis, or sloping a little backwards, with the ex- 
tremities somewhat rounded. When the celluliferous side, thus com- 
pressed in the direction of the cellules, is uppermost on the surface of 
the shale, a lme may sometimes be traced across the branch, joming the 
upper edges of the serratures, and being in fact the continuation of the 
cell-margins flattened against the stipe, while the extremities project on 
either side. 
In this way we have a great variety of aspects: the smooth surface of 
the branch, with minute striations upon the outer side; the inner side, 
when not compressed, having cellules showing as indented lines across the 
surface (1); the double serration produced by a greater pressure in the same 
direction, or with the back of the stipe uppermost (2) ; again, as the branch 
is gradually turned around, these serratures disappear from one side, 
and become more prominent upon the other (3), finally showing their full 
breadth as the branch is compressed in its transverse or lateral direction.* 
My 2 3 
eee Gage Se 
The specimens examined are in a finely laminated greenish-black shale. 
EXPLANATIONS OF FIGURES OF GRAPTOLITHUS FLEXILIS, Hall. 
Puate X. 
3. A fragment of slate preserving more than half of a frond, and showing the 
folding and crossing of some of the branches. 
4, A fragment preserving parts of three individuals, the extremities of the branches 
all broken off. 
5. The central portion of the frond of another individual. 
6. Separated branches preserving the cellules in unusual perfection. 
7. An enlargement of the centre of the frond, showing the short radicle and the 
usual mode of branching. The central part of the axis is rounded, with a 
narrow corneous alation at the sides. 
8. A bifurcated fragment enlarged: the cellules have been flattened vertically, 
causing them to be visible in slight indentations on both sides of the axis. 
9. <A portion of a branchlet enlarged, showing one part compressed laterally, 
with the cellules fully expanded, while the other, on the right hand, is 
gradually twisted so as to show only the back of the branchlet. 
Formation and Locality.—Quebec group ; Point Lévis. 
* These illustrations of the effects of pressure upon the cellules were given in the 
Report of the Geological Survey of Canada for 1857. 
