fA=0.29mm. 



Measurements. Aperture-, ..,. Zooecia 



Ua=0.2omm. 



290 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



by a smaller circular lacuna. The aperture is suborbicular with a concave lower lip. 

 The ovicell is enormous, globular, very prominent, pierced with small pores widely 

 spaced. The ovicelled zooecia bear at the right and left of the aperture two large, 

 symmetrical lamellae forming a sort of peristomie. The operculum never closes the 

 ovicell. On each zooecium there are one or two large, oval avicularia very promi- 

 nent and triangular, with a pivot, the point turned toward the aperture. 



[3=1.00-1.10 mm. 



1/3=0.45 mm. 



Variations. The more or less complete arch which is formed above the aper- 

 ture of the ovicelled zooecia is evidently designed to facilitate the passage of the 

 eggs and is a pseudo peristomie. The small lacuna is not always present (figs. 

 11, 12) ; the aspect is then that of a true M embraniporella. On the old zoaria 

 (fig. 11) the gymnocyst is thickened and shows a mural rim around the cribriform 

 area. 



In this species the lateral clefts are the intercostal spaces. In figure 12 notably 

 the lumen is clearly visible in the costules and in the broken zooecia. The costules 

 appear to be hollow. 



We note again that the operculum does not close the ovicell as in the other 

 species of the genus. 



In the future it may be necessary to classify this species in the genus Corbulipora 

 MacGillivray, 1895, when we are better acquainted with the structure of that genus. 



Affinities. This species is very close to M embraniporella agassizi Smitt. 1873, 1 

 which lives to-day in the Gulf of Mexico and in the waters off Florida. It is dis- 

 tinguished by the absence of a transverse rib on the ovicell, by the different form 

 of the avicularia and the larger micrometric dimensions (Za=0.25 mm. and not 

 0.16 mm.). 



The genus Corlulipora, is a member of the Cribrilinidae with a vincular 

 zoarium, but quadriserial. In our species the zooecia are in six series and appear 

 to differ otherwise generically. 



It is moreover quite remarkable to find in the Eocene species almost identical 

 with those now living off the coast of Florida. This is proof of the calm tectonic 

 conditions in this region during all the Tertiary period. 



Occurrence. Vicksburgian ("Chimney rock" of Marianna limestone): One 

 mile north of Monroeville, Alabama (common). 



Cotypcs. Cat. No. 64258, U.S.N.M. 



Genus CRIBRILINA Gray, 1848. 



1848. Cribrilina GEAY, List British Animals in British Museum, pt. 1, Centroniae, p. 116. 

 ItiliUographv (Anatomical). 1894. LEVINSEN, Zoologica dauica, p. 61, pi. 5, figs. 7-22. 1900. 

 WATERS, Bryozoa from Franz Joseph Lflnd, Linnean Society Journal, Zoology, vol. 28. p. 52, 

 pi. 8, figs. 21, 22. 1903. NOKMAN, Notes on the Natural History of East FinruarU, Annals 

 Magazine Natural History, ser. 7, vol. 12, p. 93, pi. 8, fig. 10. 1909, LEVINSEN, Morphological 

 nnd Systematic Studies on the Cheilostomatous Bryozoa, p. 158, pi. 9, fig. 11. 



1 1875, Smitt, Floridan Bryozoa, Kongl. Svenska Vetenskaps-Akademiens Handlingar, vol. 10, p. 11, 

 pi. 5, figs. 103-106. 



