ABT. 22. 



(JYCLOSTOMATOUS BEYOZOA CANU AND BASSLER. 



23 



Genus BISIDMONEA D'Orbigny, 1852. 



1852. Bisidmonea d'Okwgny, Paleontologie francaise, Terrain Cretac^, 

 vol. 5, p. 720. 



The ovicell is a long convex sack located on the zoarial crest and 

 deranging all the adjacent tubes; the oeciostome is terminal, placed 

 on the median axis, somewhat salient, not reflexed, of the size of an 

 ordinary peristome, somewhat transverse. The tubes are arranged 

 in irregular fascicles, much expanded, with method of gemmation 

 doubtful, closed by a zooecial area (metopoporinan) which is per- 

 forated by the orbicular aperture. 



Fig. 3. — Brachysoecia convexa, new species. 



A. Longitudinal section, X 16, showing the axial tube, the zooecial apertures 

 and facette. 



B. The same features as seen in a transverse section, X 16. 

 Cretaceous (Cenomanian) : Le Mans (Sarthe), France. 



Genotype. — Bisidmonea antiqua D'Orbigny, 1852 {=:Spiropora 

 tetragona Lamouroux, 1821). Bathonian. 



Historical. — The character upon which this genus was formed by 

 D'Orbigny was the special arrangement and the alternation of the 

 rows of tubes on tetragonal zoaria. The general aspect is that of two 

 specimens of Idmonea united together by their dorsal. Haime in 

 1854 and Gregory in 1896 have established that the genotype B. 

 20107— 22— Proc. N. M. vol. 61 WA 



