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PROCEEDINGS OF THE NATIONAL MUSEUM. 



cellular face of the branches. The zoaria may attam the size of the 

 hand. We have frequently found the ovicells broken. 



In longitudinal section the tubes are cylindrical with peristome; 

 they are oriented toAvard the exterior, but they branch at. all heights, 

 as in the zoarial form Frondipora. There is no basal lamella. The 

 zoarial walls are very thick, and are formed of a much developed 

 and very irregular lamellar tissue; the lamellae are separable. 



The mesopores of the exterior face are divergent; they are not 

 exactly parallel to the recurved extremity of the tubes; their section 





Fig. 38.— Genus Reteporidea D'Orbigny, 1852. 



A-C. Reteporidea royana D'Orbigny, 1852. 



A. Longitudinal section, X 16, illustrating the mesopores to the right and the 

 vacuoles to the left. 



B. Tangential section, X IG. 



C. Transverse section, X 16. 



Cretaceous (Maastrichtian) : Royan, France. 

 D-F. Reteporidea raniosa D'Orbigny, 1854. 



D. Longitudinal section, X 16, showing the vacuoles clearly. 



E. Transverse section, X 16. 



F. Meridian section, X 16, showing the structure of the mesopores. 

 Cretaceous (Maastrichtian) : Royan, France. 



is therefore complex and has not the regularity of /Sparsicavea. 

 Moreover, the zoarial lamellae complicate even more the general 

 aspect. 



On the dorsal the lamellar tissue is quite compact and it is difficult 

 to see the nature of the dorsal pores which appear as vacuoles if 

 the preparation is not thin enough. 



In transverse section the zoarial walls appear also very thick and 

 lamellar. The tubes are polygonal. 



In the tangential section we observe some very small mesopores 

 disseminated in small numbers between the tubes. This is not the 



