Explanations of Plat>». 288 



Figures 9, 10. Opposite sides of an entire specimen showing the marks of 

 encircling or spiral tubes, probably made by a commensal annelid. 

 On one side of the specimen (fig. 9) these are preserved as ridge-like 

 casts and on the other (fig. 10) as furrows. 



The specimens represented in figures 3, 4, 5, 7, 9 and 10 are from 

 a single slab crowded with individuals of this species. 

 Chemung group. Wellsville, New Yorh. 



Pbismodictta cobynia, sp. nov. 



Page 8B. 



Figure 11. The upper portion of a very large sponge with broadly expanded 

 pnsm-faces and a coarse square reticulation. 

 Chemung group. Wellsville, New YorK 



