GRAPTOLITES—DENDROIDEA. 



25 



2.JD. retiforme Hall. (Fig. 33.) Mid-Siluric. 



Broadly funnel-shaped. Branches rather coarse, frequently bi- 

 furcating, marked externally by flexuous striae. Dissepiments 



Fig. 23- Didyonema retiforme (N. Y. State Mus. Rep.). 



thin, diameter about a fourth that of the branches ; rather oblique 

 and numerous. 



In the Rochester shale (Niagaran) of New York and Canada. 



3. D. gracilis Hall. (Fig. 34.) Mid-Siluric. 



Fig. 34. Dictyonema gracilis (N. Y. State Mus. Rep. 



