34. CANADIAN FOSSILS. 
consists of the initial point or radicle; a diverging process of similar 
character on each side, but not quite opposite; a longitudinal axis of 
greater or less extent; and a sac-like covering, or thin pellicle of grapto- 
litic test, which has scarcely assumed the form of cellules, but which is 
most extended in the direction of the common body along the solid axis. 
This little sac contains the germ of the zoophyte, which, extending itself 
as the common body in its canal along the axis, gives origin to the budding 
which develops the successive cellules and the gradual building up of the 
stipe. 
The earliest condition of development is illustrated in fig. 12 of plate B.* 
Ata farther stage of development we have the form better defined, as 
in fig. 13, where the germ has assumed the general aspect of G. pristis, 
the slender lateral processes being rectangular to the axis. 
On the left hand of fig. 8, and at the third reproductive sac below the ~ 
top, there are two germs visible, close to the sac, where the connection 
between one of these and the fibre is nearly complete. The same is shown 
in the enlarged fig. 11. 
In figure 14 we have the germ of another form, which is unequally 
developed on the two sides. Figure 15 (represented of the natural 
size) appears to be of the same species, having reached a more definite 
form. Figure 16 is an oval disc, of which several more or less defined 
specimens have been found among the young graptolites, but I have not 
been able to trace it to any known mature form. 
The specimens figs. 17 and 18 appear to be the young of G. dicornis, 
or of a similar form. In one the body is narrow, without marks of cellules, 
and the solid axis is not extended above the common body, being prob- 
ably broken off. In the other there is a greater expansion of the 
common body, but no cellules are visible, and the central portion of the 
substance is more dense, while towards the margin it is extremely thin; 
the solid axis is extended beyond the stipe, and the lateral oblique pro- 
cesses are quite perfect. This germ, with its axis and common body, had 
not begun to develop the cell-apertures on its margins, which may be 
seen at a later period. 
In nearly all the young graptolites there is an extension of the common 
body along the axis above the incipient cellules. This is observed in the 
figures referred to and in the young of G. ramosus, shown six times 
enlarged on plate A, fig. 21. 
Although I have found none of the monoprionidian forms with repro- 
ductive sacs attached, I have nevertheless observed what appear to be the 
young of some of these species, having an aspect similar to the others, 
_ 
* All the specimens of germs or young graptolites are six times enlarged, except 
figs. 11 and 17. 
