GRAPTOLITES. 15 
it is united at the base for the length of a single cellule. In G. furcatus 
the stipes are conjoined for a distance of two or three cellules above 
the base. 
In G. ramosus, a8 shown in the following figure, the lower part of the 
stipe, for a considerable distance, has a range of cellules on each side, 
parallel with the axis ; and becoming bifurcate above, it presents two stipes 
or branches, each with a single range of cellules. All the species of 
this group have a peculiarity in the form of the cellules, which will be 
noticed hereafter. 
Fig. 20. 
Y 
GRAPTOLITHUS RAMOSUS. 
These species, in their mode of growth alone, present forms which 
might be regarded as intermediate between the mowoprionidian and 
diprionidian groups; though the typical forms, G. pristis and allied 
species, never show any tendency to a division of the parts of the stipe ; 
and we shall observe, as we progress, that these forms are connected with 
other differences of structure. 
Fig. 21. 
GRAPTOLITHUS PRISTIS. 
The species of this type (Diprion or Diplograptus) are simple linear or 
é 
