April, 1917] Silurian Fossils from Ohio 197 



Cyathophyllum roadsi, s]). nov. Plate IX, Figs. 1 A-J. 



Corallum clon^^itc turbinate in its younger stages, with a tendency 

 toward eylindrical form in its later stages. Basal angle usually varying 

 between 20 and 30 degrees, but sometimes the corallum begins as a 

 narrow, sub-cylindrical growth, enlarging more rapidly later, and then 

 becoming subcylindrical again. Corallum sometimes changing its 

 direction of growth in a more or less abrupt or geniculate manner. 

 Epitheca ^\dth distinct longitudinal septal furrows, numbering 40, 41, 

 43, 44, 46, 46, 46, and 51 in the specimens here illustrated. Along 

 the interior of the wall of the corallum there is a corresponding number 

 of septa. These are alternately short and long, the shorter ones usually 

 extending scarce! >' a millimeter from the wall. In the spaces between 

 the shorter septa and the longer septa on each side dissepiments occur 

 in greater or smaller numbers, dividing the spaces into more or less 

 irregular vesicular compartments. This vesicular tissue usually does 

 not extend more than a millimeter from the wall of the corallum. 

 Even the longer septa usually do not reach the center of the corallum, 

 but terminate as ridges on the upper surfaces of the tabulae, leaving 

 the central parts of the latter more or less free. In some of the specimens 

 the vesicular tissue -unites the proximal free margin of the shorter septa 

 to one of the adjacent longer septa in such a manner as to produ^ce the 

 appearance of the bifurcation of the longer septa in a distal direction. 



Tabulae distinctly developed and complete, at least as far as the 

 narrow vesicular zone, forming a conspicuous part of vertical sections 

 of the corallum. Tabulae usually irregularly concave. When the calice is 

 deep and funnel-like, the depth equalling or exceeding the width, 

 the tabulae are correspondingly more concave and the vesicular spaces 

 are elongated in a direction more or less parallel to the lateral walls of 

 the calice. When the calice is more shallow^ the tabulae are less 

 strongly concave. No fossula has been detected. 



Along the basal half of the exterior of the corallum the location of 

 the cardinal and alar septa may be recognized distinctly by means of 

 the septal furrows, as in typical Zaphrentida. The cardinal septum 

 almost invariably lies along the convexly curved side of the basal part 

 of the corallum. In that part of the corallum where the dissepiments 

 are most abundant, usually within one millimeter of the wall, there 

 appears to be a tendency toward the deposition of steroplasm. 



From the Lilley member, forming the upper part of the 

 West Union formation, in the Zink or Corporation quarry, in 

 the eastern part of Hillsboro, Ohio. Named in honor of Miss 

 Katie M. Roads, who for several years has been giving special 

 attention to the fauna of the West Union formation in the 

 vicinity of Hillsboro, Ohio. 



Among Silurian forms, this species is sufiQcientl}^ character- 

 ized by the narrow vesicular zone, the broad area occupied by 



