EXPLANATION OF PLATES 



Plate 1 



Page 

 Figs. 1-4. M ecynoecia icaunensis D'Orbigny, 1S50 35 



1. Zoarial fragments, natural size. 



2. Large branch, X12, on which the tubes are somewhat 



visible. 



3. Young bifurcated branch, X12. 



4. Young slender branch, X12. 



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

 land. 

 Fig. 5. Trigonoecia semota, new species 37 



5. Zoarium showing two ovicells, X 12. The surface of the 



ovicells is wrinkled and the oeciostome is small. 

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

 land. 

 Figs. 6-12, Trigonoecia haimeana De horiol, 1863 39 



6. Large zoarium, natural size, of many incrusting layers. 

 7, 8. Surface of the same specimen, X12 and X25. 



9. Specimen, X12 with the ovicell incompletely formed. 

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

 land. 



10. Portion of the zoarial surface, X12, showing the con- 



centric wrinkles. 



11. Portion of surface, X25, with tubes visible. 



12. Ovicelled portion of the surface, X12. 



Lower Cretaceous (Aptian) : Faringdon, England. 



94 



