258 The Ohio Journal of Science [Vol. XVII, No. 7, 



about 21 stronger radiating striae, separated by an equal number 

 of finer striae. Intercalated with these two sets is a third set of 

 still finer striae, about 40 in number, and finally, toward the 

 margins, there are still finer striae, visible only under a lens, so 

 that the total number of radiating striae must equal about 150. 

 These are crossed by numerous, fine, sharp, concentric lines. 

 The median depression, seen in the figure, is regarded as due to 

 pressure, resulting in flattening and moderate distortion. 



EXPLANATION OF PLATES. 



Plate VI IL 



Fig. L Zaphrentis digoniata. A, right side; B, anterior side; C, basal view, 

 witli corallum inclined so as to show more of the right side; D, E, two 

 silicified specimens, showing the cardinal fossula, sides of calice 

 weathered away. F, view of cast of interior of calice; G, lateral view, 

 showing cast of cardinal fossula. A-E, from top of West Union forma- 

 tion, in Zink quarry, at Hillsboro, Ohio. 



Fig. 2. Calostylis parvula. A. specimen showing pores in central area and 

 through the septa; also showing lateral connections or synapticula 

 between the outer part of the septa; also shown enlarged in figure 5, on 

 plate II. B, C, lateral views of two specimens. D, E, calicular views 

 of two specimens. F, view of E, enlarged 4 diameters, showing pores in 

 the central vesicular mass, and several distinct synapticula on the 

 left side of the figure. From the upper part of the Laruel limestone 

 at the Reinheimer quarry, southwest of New Paris, Ohio. 



Fig. 3. Holophragma calceoloides. A, B, right side of two specimens; C, D, 

 anterior views; E, F, G, posterior views. H, anterior view with speci- 

 men inclined so as to show interior of a nearly circular calice; I, same 

 specimen, enlarged 4 diameters. J, K, similar views of a .specimen 

 with a more flattened cardinal side. In both H and J the anterior 

 margin of the calice is weathered away. From the top of the West 

 Union formation, in the Zink cjuarry, at Hillsboro, Ohio. 



In all figures, a indicates the location of the alar septa; c, of the cardinal 

 septum; f, the cast of the cardinal fossula; x, the slightly more prominent lateral 

 septa in some specimens of Holophragma. 



