94 PKOCEEDINGS OF THE NATIONAL MUSEUM. vol. 61. 



Occurrence. — Cretaceous (Campanian) : Lon<^uesse (Seine-et- 

 Oise), Montmoreau and Courgeac (Charente), France. 



Cretaceous (Maastrichtian) : Poulipiac (Le Gabriel), Mouchaud, 

 Bessac, Barbezieux and Manie Roux (Charente) and of Roy an 

 (Charente inferieure), France and Maastricht, Holland. 



RIPISOECIA, new genus. 



(Greek. Bipis, fan, alluding to the form of the ovicell.) 



The ovicell is a flabelliform vesicle, little convex, striated trans- 

 versally. The tubes are cylindrical, long, with peristomes, recurved 

 in their distal part; their walls are hollow in the axial portion and 

 vesicular in the terminal portion. The mesopores are closed by a 

 calcareous lamella. 



Genotype. — Riphoecia {Millepora) conifera Lamouroux, 1821. 

 Bathonian. 



Affinities. — The ovicell appears to much resemble that of Terebel- 

 laria. As the specimen which we figure is the only ovicelled one 

 we have not dissected it to study the nature of the walls. The plac- 

 ing of this genus in the family Plagioeciidae is therefore possible, 

 although the ovicell in its position shows a resemblance to the Cerio- 

 cavidae. Certain incompletely developed ovicells of the genus Cer'io- 

 cava have an identical form ; and we have found a small rectangular 

 ovicell analogous to that which we figure for Ceriocava coTymhosa 

 Lamouroux, 1821. 



RIPISOECIA CONIFERA Lamonroux. 1821. 



Plate 15, figs. 1-8. 



1821. Millepora conifera Lamouroux, Exposition metliodique des genres 



tie I'ordre des Polypiers, p. 87, pi. 83, figs. 6, 7. 

 1896. Heteropora conifera Gregory, Catalogue fossil bryozoa in the 



British Museum, Jurassic, p. 202, figs. 19, 20 (Bibliography). 



Structure. — Our studies and sections have been made on the two 

 forms Heteropo7'a ramosa Michelin, 1846, and Heteropora reticulata 

 Haime, 1854. They do not confirm figure lOa of Gregory for we 

 have not observed the diaphragms. 



The transverse section is that of the zoarial form Heteropora. 

 In the center the tubes are of the same size ; they are therefore cylin- 

 drical. In the periphery the terminal, recurved portion of the tubes 

 is shown through their length ; their walls, like those of the meso- 

 pores, also are vesicular; their internal surface is striated trans- 

 versally. 



The longitudinal section shows tubes rigorously cylindrical with 

 peripheral gemmation; they are recurved almost at right angles to 

 the zoarial axis at their extremity and their walls are vesicular. The 



