Fossil Dictyospongidae of the Devonian and Carboniferous 



Formations. 



NEW F0KM8 OF DICTYOSPONGIDiE FEOM THE ROCKS 



OF THE CHEMUMG GROUP.* 



By James Hall. 



Since the publication of the preliminary discussions of the 

 'genera and species of this remarkable group of organisms, much 

 -additional material of interest has come into my hands, largely from 

 the rocks of the Chemung group in Alleghany and adjoining 

 counties in the State of New York. This formation has already 

 furnished fourteen species of the genus Dictyophtton, besides the 

 curious basket sponge, Uphantaenia and probable, though incom- 

 plete, evidences of the genera Phragmodictya and Ectenodictya. It 

 is now necessary to add two other genera to this number, viz., 

 AcTiNODiCTYA and Cryptodictya. The group proposed for dis- 

 cussion in my final work on the reticulate sponges now includes 

 twelve genera and subgenera represented {at present) by forty-six 

 species. Of the latter, two are from the Utica slate, one from the 

 Hamilton shales, twenty-four from the Chemung group, seven 

 from the Waverly and twelve from other horizons of the lower 

 carboniferous period. 



There are at least two other species remaining undescribed, and 

 by the end of the present season I expect to record at least fi^fiy 

 species of this family of sponges. 



DlOTYOPHYTON SCEPTRUM, Sp. B. 



Cup circular to elliptical in transverse section; subcylindrical, 

 usually abnormally compressed, rarely curved; tapering toward the 

 base and narrowing more abruptly to the aperture. 



Point of attachment not observed. 



Surface without nodes or irregularities except those arising from 

 distortion in fossilization; coarsely reticulated by longitudinal and 

 transverse spicular bands. The primary bands form comparatively 

 large rectangular meshes which are subdivided by the crossing of 

 the subordinate bands. 



*Bee first published notice of the following species in the Proceedings of the Geologi- 

 cal Society of America. 



