AKT. 21 CYCLOSTOMATOUS BRYOZOA CANU AND BASSLER 19 



small cones replace a consolidated tube. This is not the case here. 

 More material is necessary in order to establish the nature of the 

 genus Acanthopora. 



Occurrence. — Lower Cretaceous (Valangian) : Sainte-Croix (Vaud), 

 Switzerland. 



Holotype.—Csit. No. 69859, U.S.N.M. 



Genus SEMINODICRESCIS D'Orbignj, 1854 



SEMINODICRESCIS NODOSA D'Orbigny, 1854 



Plate 22, fig. 1 



1854. Seminodicrescis nodosa D'Orbigny, Pal6ontologie francaise, Terrain Cr6- 

 tace, vol. 5. p. 1067, pi. 800, figs. 12-14. 



Our zoariiim is smaller than that figured by D'Orbigny, but the 

 aspect is very much the same. It is hollow and thin at the two 

 extremities. The nodosities do not present any particular character 

 and correspond to the mammillosites of many other species belong- 

 ing to the genus Multicrescis D'Orbigny, 1854. As we have not 

 been able to make any section, we maintain D'Orbigny's name. 



Occurrence. — Lower Cretaceous (Aptian) : Faringdon, England. 



Geologic distribution. — Lower Cretaceous (Aptian), Saint-Dizier 

 (Haute-Marne), and Les Crofites (Aube), France (D'Orbigny). 



Plesiotype.—Ca.t. No. 69861, U.S.N.M. 



Genus CERIOPORA Goldfuss, 1827 



and 



Genus REPTOMULTICAVA D'Orbigny, 1854 



In Ceriopora the colonies are unilamellar, more or less massive or 

 lobed, and formed of cylindrical tubes without peristomes and with 

 peripheral [gemmation. In Reptomulticava the zoaria are multi- 

 lamellar. 



The structure of these genera is not as simple as their diagnoses 

 would indicate. In thin sections they present important peculiari- 

 ties for observation. 



Zonal lines. — In longitudinal or meridian sections the zonal lines 

 are curved concentric regular bands of very little width. They are 

 closer together at the summit of the colony than at the base. They 

 do not interrupt the tubes as the diaphragms. They are transformed 

 frequently in a part of their length into basal lamellae supporting 

 not subcolonies but series of tubes differently oriented {Ceriopora 

 ovoidea, C. fiolida, C. lohifira) . This phenomenon is more frequent in 

 the lateral portions of the colonies, where it is manifested externally 

 by the lamellae appearing entirely surrounding the colony {Cerio- 

 pora') or superposed {Drfranciopora). 



