20 CANADIAN FOSSILS. 
correspondingly subdivided. Neither the central portion, nor any of its 
subdivisions, becomes celluliferous ; and these parts are not termed stipes 
or branches, according to the views I have entertained. It is only beyond 
the last subdivisions of this part of the body, as in G. Logant, that the 
celluliferous parts, or the true stipes, commence. 
In one of the proper branching forms, however, the cellules begin 
immediately beyond the first subdivisions of the funicle, as in the four- 
stiped species. (Fig. 27.) 
GRapPtoLtitaus Minzsi. 
These barren, or non-celluliferous portions of the graptolitie body, are 
not otherwise essentially different from other parts of the stipe. In the 
absence of cellules they are consequently more cylindrical, and apparently 
more solid, asif the test were thicker, and the common canal less developed 
than in the other parts of its extent. 
3. The Central Dise.—In several of the species having four simple 
stipes, in one species with eight, and in another with a larger number of 
simple stipes proceeding from a common centre, we find their bases 
united by a thickened corneous expansion of the same substance as the 
body of the graptolite. This appears to be composed of two laminz, 
which, at least in the central portions, are not conjoined, and the space-is 
probably occupied by some softer portion of the animal body. (Plates v-ix.) 
The substance of the disc sometimes extends along the margins of the 
stipes, producing an alation, as in G. alatus. (Pl. vi, fig. 9.) 
This arrangement of the parts of the body seems obviously adapted to 
give strength and support to the bases of the stipes ; but: beyond this it 
probably serves other purposes of the animal economy. In several 
specimens of G. bicornis there is a disc or bulb at the base of the stipe, 
which, spreading between the two oblique curving processes, envelopes, in 
the compressed condition of the specimens, some of the celluliferous part 
