EXPLANATIONS OF PLATE XVIL 



Dendrograptus flexuosus, page 127. 



Fig. 1. A small frond of the natural size. 

 2. A part of a larger frond. 



Dendrograptus divergens, page 129. 



Figs. 3, 4. A specimen of natural size, and an enlargement of the same. 



Dendrograptus striatus, page 129. 



Fig. 5. A fragment of a frond, preserving the bases of some of the branches. 

 " 6. A portion of the non-celluliferous surface enlarged. 



Dendrograptus erectus, page 130. 

 Fig. 7. The principal stipe, and bases of some of the branches, of the natural size. 



Dendrograptus fruticosus, page 131. 



Fig. 8. A frond which is apparently nearly entire. 

 " 9. A more diffuse form of the same species, with some of the branches broken off. 



