PLATE V. 



Fig. 1. — Olathrodictyon regulare, Rosen ; vertical section, enlarged 12 times. 

 Wenlock Limestone, Dudley. 



Fig. 2. — Tangential section of the same, similarly enlarged. 



Fig. 3. — Olathrodictyon striatelJ/wm, D'Orb. ; vertical section, enlarged 12 

 times. Wenlock Limestone, Benthall. 



Fig. 4. Tangential section of the same, similarly enlarged. 



Fig-. 5. — Olathrodictyon vesiculosum, Nich. and Mur. ; vertical section, 

 enlarged 12 times. From the type-specimen of the species, Yellow Springs, 

 Ohio (Clinton Formation). 



Fig. 6. — Olathrodictyon variolare, Rosen; vertical section, enlarged 12 times, 

 as, as, cut ends of the astrorhizal canals. Wenlock Limestone, Dormington. 



Fig. 7. — Tangential section of the same, similarly enlarged. 



Fig. 8. — Stromatopora antiqua, Nich. and Mur.; a weathered specimen, of 

 the natural size, showing the " latilaminaB." Niagara Limestone, Thorold, 

 Ontario. 



Fig. 9. — Part of a vertical section of the same, enlarged about twice. The 

 " latilaminaa" are only partly in contact, and the spaces between them are filled 

 with the matrix. 



Fig. 10. — Vertical section of the same, enlarged 12 times, showing the 

 delicate tabulate zooidal tubes. 



Fig. 11. — Tangential section of the same, enlarged 12 times, showing 

 the cross-sections of the zooidal tubes as minute apertures in the skeletal 

 framework. 



Pig. 12. — Stromatopora Beuthii, Barg. ; tangential section, enlarged 12 

 times. The section shows the coarsely-porous skeleton-fibre and the persistence 

 of the radial pillars, the cut ends of which (pp) appear immersed in the general 

 reticulation. Devonian, Hebborn (Paffrath district). 



Fig. 13. — Vertical section of the same, similarly enlarged, showing the 

 tabulate zooidal tubes, and the persistence of the radial pillars (p p) in the interior 

 of the skeleton-fibre. 



Fig. 14. — Stromatopora typica, Rosen; tangential section, enlarged 12 

 times. The section shows the completely reticulate character of the skeletal 

 tissue and the minutely porous structure of the skeleton-fibre. The apertures 

 in the skeletal network are the cross-sections of the zooidal tubes. No traces 

 of the radial pillars, as distinct structures, can be detected. Wenlock Limestone, 

 Ironbridge. 



Fig. 15. — Vertical section of the same, similarly enlarged. The figure takes 

 in the thickness of a single " latilamina," and shows the tabulate zooidal tubes. 



Fig. 16. — Stromatopora concentrica, Goldf., var. colliculata, Nich. ; tangential 

 section, enlarged 12 times. Middle Devonian, Gerolstein. 



Fig. 17. — Vertical section of the same, similarly enlarged. The figure shows 

 that the reticulated skeleton exhibits traces of the concentric lamina?. The 

 section is slightly oblique, and the tabulate zooidal tubes are, therefore, not well 

 shown. 



