Plate 15 



Page 

 Figs. l-d. Latcrocdvca dutcmplcana D'Orbigny, 1853 85 



1,2. A l:)ifvircated frond, natural size and X12, showing 

 the broad celluliferous frontal face. 

 3. Celluliferous face, X25. 

 4, 5. Lateral noncelluliferous face, X12 and X25. 



6. Tangential thin section, X25, showing the arrange- 



ment of the mesopores around the peristomes. 

 Lower Cretaceous (Aptian) : Faringdon, England. 

 Figs. 7-10. Zonopora arborea Koch and Dunker, 1837 90 



7. Zoarial fragments, natural size. 



8, 9. Portion of a specimen, X12 and X25, exhiljiting no 

 zones of mesopores. 



10. Specimen, X12, showing a false ovicell. 



Lower Cretaceous (Valangian) : Sainte-Croix, Switzer- 

 land. 

 Figs. 11-14. Sparsicavea irregularis D'Orbigny, 1853 91 



11. Specimens, natural size. 



12. A reticulated specimen, X12. 



13. Specimen showing the large areas of mesopores, X12. 



14. Same specimen, X25. The apertures are rounded 



and the mesopores are polygonal. 

 Lower Cretaceous (Aptian): Faringdon, England. 

 Figs. 15-17. Zonopora compressa, new species 90 



15. Fragments, natural size. 



16, 17. A bifurcated frond, Xr2, and portion, X25. 

 Lower Cretaceous (Valangian) : Sainte-Croix, 

 Switzerland. 

 108 



