38 



PROCEEDINGS OF THE NATIONAL MUSEUM, vol. 61. 



Genus LATEROCEA D'Orbigny, 1852. 



1852. Laterocea d'Okbigny, Paloontologie frangaise, Terrain Cr^ta6e, vol. 5. 

 p. 1003. 

 The oeciopore is a very small pore. The tubes are cylindrical, 

 branched, dilated at their distal extremity; the walls are thick at 

 their extremity. 



Genotype. — Laterocea sim'plex D'Orbigny, 1852. Cretaceous (Se- 

 nonian). 



LATEROCEA SIMPLEX D'Orbismy. 1852. 



Plate 7, fig. 6. 



1852. Laterocea simplex d'Obbigny, Paleontologie franr-aise, Terrain 

 Crgtace, vol. 5, p. 1004, pi. 786, figs. 14-16. 

 Structure. — Exteriorly the zooecia of Laterocea simplex are ar- 

 ranged in transverse rows, the feature upon which D'Orbigny founded 



Fig. 7. — Laterocea simplex D'Orbigny, 1852. 



A. Transverse section, X 16. 



B. Longitudinal section, X 16. The tubes are cylindrical and have their ter- 

 minal walls thickened. 



Cretaceous (Couiacian) : Villedieu (Loir et Cher), France. 



the genus, but this character is rather variable and can not be generic. 



In transverse section we note that the tubes are almost of the same 

 diameter, as in all the species with cylindrical tubes. The zoarial 

 margins are very thick, which implies a considerable thickness of the 

 extremity of the zooecial walls. 



In longitudinal section the tubes are cylindrical in the greater part 

 of their length; they are not oriented, but are dichotomously 

 branched. This mode of gemmation gives to the zoaria a great irreg- 



