PLATE VI. 



Fig. 1. Beceptaculites Oweni. Section transverse to the radial pillars showing 

 the latter to be solid and structureless. X 4. 



Fig. 2. J^. Oweni. Section through the gastral wall near the inner surface, 

 showing by the dark portion irregular, anastomosing channels filled with 

 matrix, and cutting the structureless calcite of the inner wall. X 4. 



Fix. 8. R. Oweni. Section through the outer wall. The dark portion repre_ 

 sents what is generally considered matrix thrust between the summit 

 plates. At the corners of the plates are round pores which are usually 

 supposed to be characteristic of the inner wall. X 4. 



Fig. 4. A diagrammatic representation of a relief ornamentation preserved as 

 a cast in the matrix above the rhombic pits of the external surface of a 

 specimen of R. Oweni, 



Fig. 5. Clathrodictyon Jewetti. Longitudinal section showing the discontinu- 

 ous radial pillars. X 15. 



Fig. 6. Transverse section of the same showing the cut ends of the radial pillars 

 which are not joined by connecting processes. The skeleton-fiber is seen 

 to be dense, not reticulated as in the genus Syringostroma. X 15. 



Fig. 7. Syringostroma microporum. This is a transverse section, showing the 

 finely porous structure of the laminae and the minutely reticulated skele- 

 ton-fiber. A mamelon with axial tube and astrorhizal canals is cut in the 

 lower right hand portion of the figure. X 15. 



Fig. 8. Syringostroma foveolatum. Transverse section showing an extended 

 astrorhizal system, and illustrating the dense character of the skeletal tis- 

 sue. X 15. 



Fig. 9. Longitudinal section of the same. The figure shows the thick laminae 

 and continuous radial pillars; at the same time it traverses an axial tube 

 and illustrates the superimposed nature of the monticules. X 15. 



