KORTH AMERICAN KARLY TERTIARY BRYOXOA. 829 



FIG. 275. Genus Tretocycloecia Canu, 1919. 



A-I. Tretocycloecia (Heteropora) dichotoma Reuss, 1847. A. Zoarium, natural size. B. 

 Surface, X 25, showing ovicell pierced by the tubes with accompanying mesopores. C. Interior 

 of the ovicell, X 25. D. Surface of specimen, X 12, showing ovicell covered by a new layer of 

 tubes and made visible by fracture. E. Another example, X 12, showing the interior of the ovi- 

 cell. F. Tangential thin section, X 25. G. Surface of zoarium, X 15. H. Vertical thin section, 

 X 25. I. Transverse thin section, X 25. 



Helvetian of Doue la Fontaine (Maine et Loire) and Mus (Card), France. 



