PLATE XIII. 



Fig. 1. — Tangential section of a specimen of Actinostroma clathratum, Nich., 

 enlarged 10 — 12 times. This form possesses strong but irregularly developed 

 radial pillars. Middle Devonian, Teignmouth. (Page 133.) 



Fig. 2. — Vertical section of the same specimen similarly enlarged. 



Fig. 3. — Portion of a polished specimen of Actinostroma bifarium, Nich., of the 

 natural size. Middle Devonian, Teignmouth. (Page 136.) 



Fig. 4. — Tangential section of Actinostroma bifarium, Nich., enlarged 10 — 12 

 times. Middle Devonian, Teignmouth. 



Fig. 5. — Vertical section of the same, similarly enlarged. 



Fig. 6. — Tangential section of a specimen of the same from the Middle 

 Devonian of Buchel (Paffrath District), enlarged 10 — 12 times. 



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



Fig. 8. — Upper surface of a broken discoidal specimen of Actinostroma inter- 

 textum, Nich., of the natural size. Wenlock Limestone, Ironbridge. (Page 138.) 



Fig. 9. — Part of the surface of the same, enlarged twice. The specimen shows 

 much more conspicuous astrorhizse than is usually the case in this species. 



Fig. 10. — Tangential section of Actinostroma intertextum, Nich , enlarged 12 

 times. Wenlock Limestone, Ironbridge. 



Fig. 11. — Vertical section of the same, similarly enlarged. 



