174 



TWENTIETH REPORT ON THE STATE CABINET. 



In some species of this mode of growth, the bases of the stipes are 

 united in a more or less expanded disc or cup of the same substance as the 

 body of the graptolite. The form of this disc is shown in the accompa- 

 nying figure of Graptolithus headi. 



In a further development in the same direction, we have fronds with 

 eight simple stipes, which may or may not be united in a central disc, as in 

 the accompanying figure of G. octohrachiatus. 



Fig. 4. 



Graptolithus octobrachiatus. 



In Graptolithus logani we have numerous simple stipes united in a 

 central disc or cup ; while in some specimens otherwise precisely similar, 

 we have no remains of the disc. In all these species the parts are dis- 

 posed in a symmetrical and bilateral arrangement. 



