GRAPTOLITES. 131 
DENDROGRAPTUS FRUTICOSUS, Hall. (n.s.) 
Plate XVII, figures 8, 9. 
Description.—Frond robust. Stipe strong, rounded below, and sometimes 
terminating in a root-like expansion, flattened above, and irregularly bifur- 
cating; the branches frequently subdivided, the bifurcations continuing 
almost to the extremities. Branches and branchlets somewhat rounded and 
undulating or zigzag in direction, smooth or indistinctly striated on the non- 
celluliferous side.  Cellules in alternating series on the opposite margins of 
the celluliferous side, and distant about twice the width of the branch ; 
from about thirty-three to thirty-six in the space of an inch; swelling 
out towards the apertures, and giving the undulating appearance to the 
branches. Cell-denticles angular or sub-angular, twice as long on the 
lower slope as on the upper or aperture side. ‘The cellules make an 
angle with the axis of apparently between 25° and 35°. 
This species is abundant in the coarse shales which contain Phyllograp- 
tus typus. The-general aspect is that of a delicate plant, and it requires 
careful observation to detect the celluliferous character of the branches ; 
the celluliferous side also more frequently adheres to the stone. In the 
impressions thus léft after the removal of the substance of the branch, as 
well as upon the branches themselves, we see the cellules arranged on the 
margins in alternating series, but with the apertures opening on the same 
side. 
Whenever the pressure has been upon the non-celluliferous side, and that 
side is exposed, the evidence of cellules consists of little more than 
enlargements of the sides of the branches. When a stipe is turned alittle 
on one side, a row of cellules becomes visible ; and a further turning of the 
branch discloses the two series, or the alternating ranges of cellules. The 
form of the cell-denticle is much influenced by the direction of the pressure 
upon the branches, and also by the character of the surrounding matrix. 
The root-hke expansion at the base does not appear to.have been more solid 
than the stipe above, and is in appearance not unlike the central discs of 
the uniserrate graptolites. 
EXPLANATIONS OF Figures or DeNDROGRAPTUS FRUTICOSUS, Hall. 
“Pirate XVII. 
g. <A frond which is apparently nearly entire. : 
9. A more diffuse form of the same species, with some of the branches broken off.- 
Formation and Locality. Quebec group; Point Lévis. 
