Explanations of Plates. 281 



ARYSTIDICTYA, gen. nov. 



Page i:»6. 

 (See Plate XLII.) 



ARYSTIDfCTYA KLEOANS, Sp. nOV. 



Page 136. 



(See Plate XLII.) 



Figure 10. One side of the typical specimen which is preserved from the 

 base or basal disc to the aperture. The drawing has intensified the 

 wrinkles of the reticulum resulting from a slight foreshortening, 

 and fails to give with proper force the regularly reticulating bands 

 which are clearly apparent especially over the lower part of the 

 sponge. The marginal radiating channels about the edge of the vase 

 are well shown. 

 Lower Chemung group. Cotton hill, iiea/r Avoca, New Yai'Jc. 



Aeystidictya nodifeba, sp. nov. 



Page 137. 



Figure 11. The specimen described; a portion of a vase-shaped sponge like 

 A. elegans, having the sui-face covered with elongate, irregularly 

 disposed nodes. 

 Lower Chemung group. Cotton hill, near Avoca, New Yoi'h. 



HALLODICTYA, gen. nov. 



Page 140. 

 (See Plate XXXVI.) 



Hallodictya Cottoniana, sp. nov. 



Page 142. 



Figure 12. A fragment of a frond having a sharply, somewhat irregularly 

 reticulate surface, free of nodes. 

 Lower Chemung group. Cotton hill, tiear Avoca, New Yorh. 



