GRAPTOLITES. 89 
The specimen originally described under this name is a fragment (pl. iv, 
fig. 14), consisting mainly of an imprint in the shale, the substance 
of the fossil being preserved in some parts. ‘The solid axis on the 
denticulate margin is clearly defined in the impression, and in some 
places the substance remains, and is expanded at each denticle on the upper 
side so as to occupy the base of each depression. The cellules terminate 
in so minute a point that no aperture is visible ; but in a longitudinal divi- 
sion of some of them, they appear to have been hollow tubes. The back of 
the stipe is clearly marked (as is usual in the graptolites) by the presence 
of a distinct solid axis, which in no respect differs from the ridge on the 
opposite margin, except that the latter extends into the base of the cellules. 
A further study of the collection has shown that some obscure imprints 
in weathered shale are of the same species. ‘These imprints, at a few points, 
retain portions of the pellicle, and the form of the cellules is well preserved ; 
they reveal moreover the mode of growth, as shown in figs. 12 and 13 
of pl. iv; thus indicating. their relation im this respect to G. bryonoides 
andG. quadribrachiatus. The recurved position of the stipes is a feature 
of G. bryonoides, but less extreme than in this one. This species may be 
readily identified by the pointed cellules, vertical to the axis, which appear 
to be entirely separated from the common body, except in well-preserved 
portions, where in a few examples they are shown to be connected at the 
base by a continuation of the cell-wall above the solid axis. 
EXPLANATIONS OF FIGURES OF GRAPTOLITHUS DENTICULATUS, Hall. 
Puate IV. 
12. A small imperfect specimen, preserving three of the stipes. 
13. A larger and more nearly entire specimen, showing the four stipes. Their junction 
at the base is not quite satisfactorily shown. 
14. A part of a single stipe, in which the cellules are well shown on one part; while 
they are compressed and nearly obliterated on the left of the curve. 
15. An impresssion of a part of a stipe which is nearly straight; the imprint of the 
axes or thickened margins is not defined. 
16. An enlargement from figure 14, showing the form of the cell-denticles, and the 
strong marginal axes ; one portion represented with the substance remaining, 
and the other as an imprint. 
Formation and Locality.—Shales of the Quebec group; Point Lévis. 
