PLATE XXIV. 



Fig. 1. — Vertical section of Stromatopora Beuthii, Barg. (?), in the " Cauno- 

 pora-state," enlarged about 10 times. Middle Devonian, Teignnioutk. 



Fig. 2. — Part of the surface of a specimen of Stromatopora discoidea, Lonsd., 

 of the natural size, showing the form and arrangement of the astrorhizse. Wen- 

 lock Limestone, Dudley. 



Fig. 3. — Small portion of the surface of a specimen of Stromatopora discoidea, 

 Lonsd., enlarged 5 times. Wenlock Limestone, Gotland. 



Fig. 4. — Part of the surface of the preceding specimen, still further enlarged. 



Fig. 5. — Skeleton-fibre of Stromatopora discoidea, enlarged about 40 times. 



Fig. 6. — Tangential section of a very well preserved specimen of Stromatopora 

 discoidea, Lonsd., enlarged about 10 times. Wenlock Limestone, Ironbridge. 



Fig. 7. — Vertical section of the preceding specimen, similarly enlarged. 



Fig. 8. — Tangential section of the Stromatopora elegans of von Rosen, enlarged 

 ten times. This form is in reality based on an example of S. discoidea, Lonsd., 

 in a considerably altered state, and the specific name " elegans " must therefore be 

 abandoned. The specimen is from the Silurian Rocks of Kleine Ruhde, in 

 Bsthonia. 



Fig. 9. — Part of a tangential section of Stromatopora concentrica, Groldf., var 

 astrigera, Nich., enlarged 10 times. The specimen is in a much altered and 

 partially "reversed" condition, and the part figured shows the centre of an 

 astrorhiza. Middle Devonian, Teignmouth. 



Fig. 10. — Surface of a polished specimen of the preceding, of the natural size, 

 showing the form and arrangement of the astrorhiza?, from the same locality. 

 The astrorhizaa have been drawn for distinctness' sake as if darker in colour than 

 the general skeleton, but they are really lighter. 



Fig. 11. — Portion of the surface of a polished specimen of Stromatopora 

 insequalis, Nich., enlarged about twice. Middle Devonian, Teignmouth. 



Fig. 12. — Tangential section of the same, enlarged about 5 times, from the 

 same locality. The specimen is in the " reversed" condition. 



Fig. 13. — Portion of a polished tangential section of Parallelopora darting - 

 tonensis, Carter sp., of the natural size, showing the astrorhizae. Middle Devonian, 

 Teignmouth. 



Fig. 14. — Portion of a polished tangential section of a "reversed" specimen 

 of the same, enlarged twice. Middle Devonian, Teignmouth. The minute struc- 

 ture of this specimen, as displayed in thin tangential section, is shown in Plate 

 IV, fig. 1. 



Fig. 15. — Tangential section of a specimen of P. dartingtonensis, Cart, sp., 

 from the Middle Devonian of Pit-Park Quarry, Dartington, enlarged 10 times. 



