242 Dktyosi'ongid/E. 



PLATE XXII. 

 HELICODICTYA, gen. nov. 



Page 114. 

 (See Plate XXVII.) 



Heucodictya trypania, sp. nov. 



Page 114. 



Figure 1 . Lateral view of a compressed specimen, showing the spiral ridges 



parallel to one of the rectangularly reticulating spicular series. 

 Figure 2. The same specimen with the lower portion removed to show the 



continuity of the spiral ridges on the impression of the opposite 



side. 



Chemung group. IVellsvllk, New Yoi'Jc. 



CERATODICTYA, gen. nov. 



Page 117. 

 (See Plates XLI, XLII, XLHI.) 



Ceratodictya axnulata, Hall (sp.). 



Page 120. 



Figures 3, 4. Opposite sides of a large specimen with broad and low 



annulations. 



Chemung group. Deyo basin, Naples, New Yorh. 

 Figure 5. The original figure of the species, showing Hve short and subequal 



aimulations. 



Figure 6. Another view of the same specimen. 



Chemung group. Western Neio Yorlc (^precise locality lost'). 



Ceratodictya cincta, Hall (sp.). 



Page 118. 



Figure 7. One side of the original specimen, showing below the disordered 



and interrupted growth of the annulations. 

 Figure 8. The opposite side of the same fragment, the growth of the 



annulations here being regular and undisturbed. 

 Figure 9. An end view of the specimen, showing the compression to which 



it has been subjected. 



Chemung group. From a boulder at Erie, Pennsylvania, 



