252 DlCTYOSPONGID^. 



PLATE XXVII. 

 HELICODICTYA, gen. nov. 



Page 114. 

 (See Plate XXII.) 



Helicodictya (?) Scio, sp. nov. 



Page 116. 



Figure 1. A fragment of a frond which appears to have had a distinctly- 

 spiral mode of growth, with strong constrictions or impressions of 

 ridges running parallel to one of the reticulating series. 

 Chemung group. Scio, Allegany county, New Yorh. 



Helicodictya (?) Concokdia, sp. nov. 



Page 115. 



Figure 2. A spii'ally growing sponge found associated with Prisinodictya 

 priHmatica in the 

 Chemung group. Qmcoi'd statwii, Erie county, Pennsylvania. 



DICTYOSPONGIA, gen. nov. 



Page 72. 

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



DlCTYOSPONGIA SCEPTRUM, Hall (sp.). 

 Page 73. 

 (See Plates XIV, XV, XVI, XXXVI.) 



Figure ?t. A small incomplete, somewhat compi-essed example with very fine 

 reticulation.' 

 Chemung group. Viellmille, Neui Yorh. 



PRISMODICTYA, gen. nov. 



Page 79. 

 (See Plates XVII, XVIII, XIX, XX, XXI, XXXIII, XXXIV, XXXV, XXXVI, XLI, XLII, LV ) 



Peismodictya filitextilis, Hall (sp.). 



Page 86. 

 (See Plate XXI ) 



Figure 4. A fragment of an uncompressed individual showing the obscure 

 prism-faces and fine reticulation, 

 Chemung group. Wellsville, New YorTc. 



