280 DlCl'YOSPONGIDiE. 



PLATE XLI. 

 CERATODICTYA, gen. nov. 



Page 117. 

 (See Plates XXII, XLII, XLIII.) 



Ceratodictya centeta, sp. nov. 



Page 120. 



Figure 1. A very young individual. 



Figure 2. A fragment of a large example. 



Figures 3, 4, 5. Specimens of medium size, showing some irregularity in the 



size of, and intervals between the annulations. 



Chemung group. Ischtm, New York. 



Ceratodictya zonata, sp. nov. 



Page 119. 



Fio-ure G. The type-specimen, showing equidistant and broad annulations. 

 Chemung group. Found loose at Erie, Pennsylvania. 



PRISMODICTYA, gen. nov. . 



Page 79. 

 (See Plates XVII, XVIIF, XIX, XX, XX[, XXVII, XXXIII, XXXIV, XXXV, XXXVI, XLII, LV.) 



PuiSMODICTYA AULOPIIIA, Sp. UOV. 



Page 88. 



(See Plates XX and XXXIV.) 



Figure 7. Fragment of a large specimen ; showing the concave prism-faces 

 and finely preserved net-work. 

 Chemung group. Wellsville, New York. 



DICTYOSPONGIA, gen. nov. 



Page 72. 

 (See Plates XIV, XV, XVI, XXVII, XXXIII, XXXVI, XXXVIII, XLI, XLII, XLIV, XLVI, LV, LVI, LXI.) 



DiCTYOspoNGiA (?) Marcellia, Clarke (sp.). 



Page 65. 



Figure 8. A portion of the suface of a piece of bituminous shale covered Avith 

 pyritized spicules of this species. 



Figure 9. An enlargement from the same, showing the cruciform spicules and 

 the broad ligulate spicules whose position in the skeleton is not yet 

 understood. 

 Marcellus shale. In the Livonia salt sliaft, Livonia, New York. 



