PLATE XVI. 



Fig. 1. — Part of a polished slab of Actinostroma verrucosum, Goldf. sp., of the 

 natural size. Middle Devonian, Teignrnouth. (Page 134.) 



Fig. 2. — Tangential section of the same, enlarged 10 — 12 times. The skeleton 

 (as so commonly is the case in specimens from the Devonian Limestones of Britain) 

 has undergone crystallization, and has been distorted by pressure. 



Fig. 3. — Vertical section of the same, similarly enlarged. 



Fig. 4. — A specimen of Actinostroma verrucosum, Groldf. sp., from the Middle 

 Devonian of Biichel (Paffrath district), of the natural size. 



Fig. 5. — Tangential section of the same, enlarged 10 — 12 times. The section 

 traverses one of the astrorhizal cylinders. 



Fig. 6. — Vertical section of the same, similarly enlarged. 



Fig. 7. — Tangential section of another example of the same species from 

 Biichel, enlarged 24 times, showing the axial canals of the radial pillars. 



Fig. 8. — One of the " mamelons " of Actinostroma verrucosum, enlarged about 

 3 times, showing the central opening of a vertical astrorhizal canal, and the 

 radiating canals of the last astrorhiza. 



Fig. 9. — Fragment of Actinostroma hebbornense, Nich., from the Middle 

 Devonian of Hebborn (Paffrath district), of the natural size. The specimen shows 

 the surface of one of the concentric lamina? as exposed by fracture. (Page 137.) 



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



Fig. 11. — Portion of the preceding section, enlarged 24 times. 



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



Fig. 13. — Tangential section of Actinostroma hebbornense, Nich., from the 

 Middle Devonian of Teignrnouth, enlarged 10 — 12 times. The structure of this 

 specimen is finer and closer than is usual in the species, and the skeleton has been 

 distorted by pressure, and partially obliterated by crystallization. 



Fig. 14. — Vertical section of the same, similarly enlarged. 



Fig. 15. — Tangential section of another example of Actinostroma hebbornense, 

 Nich., from the Middle Devonian of Teignrnouth, enlarged 10 — 12 times. This 

 specimen agrees with the type of the species in the proportions of its skeleton, and 

 likewise exhibits astrorhiza ; but, like the preceding, it has been much affected by 

 crystallization and pressure. 



Fig. 16. — Vertical section of the same, similarly enlarged. 



