SF»ECIES OK THE CARBONIFEROUS. 



SPECIES OF THE WAVERLY GROUP. 



TYLODICTYA, gen. nov. 



This generic form is as yet but imperfectly imderstood. Some recently 

 discovered sponges from Warren, Pennsylvania, present the api>earance of 

 erect, reticulated cups, smooth or somewhat irregularly undulated for a con- 

 siderable part of their length, but abruptly breaking out into one or possibly 

 more whorls of quite unsymmetrical and irregular simple or compound nodes. 

 Apparently there are eight nodes in each whorl, but this is not certain. 

 The nodes are j)endidous when large, and in their subdivision have foUoAved 

 no rule or order. The aspect of the cylindrical portions of the sponge is 

 similar to that of the forms of Calatiiosponqia with which it is associated, 

 being fine-meshed and free from prismatic faces. 



The fi'agments to which our knowledge of this genus is now restricted, 

 thoiigh higlil\- imperfect, are still sufficient to distinguish it from any other. 



Type, Tylodictya Warrenensis, sp. nov. 



Tylodictya Waerekensis, sp. nov. 

 Erect, subcylindrical cups, apparently contracting slightly above the base ; 

 surface smooth for a considerable distance, then gently expanding and 

 developing a horizontal row of nodes. In the 

 smaller of the fragments which have been ob. 

 served, these nodes are low, simple, somewhat 

 elongate vertically and divided by narrow fiirrows 

 which reach to the general surface of the sponge, 

 displaying no tendency to subdivision or irregu- 

 larity of arrangement ; in the larger specimen less 

 of the inferior surface of the cup is retained, but 

 the nodes are very strongly developed, are vertic- 

 ally elongate, and were apparently somewhat fan- 

 shaped, are pendent toward their rounded ex- 

 tremities and separated by grooves of different 

 depth, so that each pair of nodes seems to be 

 elevated on a stout base, as with the nodes in cer 

 tain species of HrDNOCERAS. Upon one side of 

 this specimen the nodes are much less regular than 

 on the other, one pair having appeared below the 

 others. This pair is divided very unequally by a 

 vertical groove and again horizontally, so that the effect produced is some- 

 what like that observed among the nodes of Botryodiotya. To what extent 



161 



Jjgb 



FiouKB 18. Viilodietya Warmeiut; War 

 ren, Penus^lvanla. A youn« fndlTldual boar 

 Ing nodes only toward the nppor part. 



