Exi'LANATIONS OK PlATKS. 271 



Pkismodicita sp. ? 

 Figure 6. A compressed, expanded and somewhat twisted frond whose 

 specific relations have not been determined. It bears some relation 

 to P.'ptionia but differs therefrom in its less abrupt expansion and 

 broader, shorter basal region. 

 Chemung group. Scio, New Yoi'k. 



DICTYOSPONGIA, gen. nov. 



Page 72. 

 (See Plates XIV, XV, XVI, XXVII, XXXIII, XXXVIII, XIJ, XLII, XLIV, XLVI, LV, LVl, LXI.) 



DlCTYOSPONGIA SCEPTBUM, Hall (sp.). 

 Page 73. 

 (Seo Plates XIV, XV, XVI, XXVII.) 



Figure 7. The basal end of a specimen, showing a portion of the long 

 anchoring tuft. 

 Chemung group. Ischua, New Ya)'k. 



IIALLODICTYA, gen. nov. 



Page 140. 

 (See Plate XLI.) 



Hallodictya Sciknsis, sp. nov. 



Page 140. 



Figure 8. Tlie original specimen, showing the expanded, irregular and nodose 

 character of the sponge. The reticulation is, in itself, regularly 

 constructed but conforms to the highly uneven surface. This 

 specimen is a mould of the exterior surface and the depressions 

 represented on the drawing indicate nodes of tlie outer surface. 

 Chemung group. Scio, New Yorh 



