l^OKTH AMERICAN EARLY TERTIARY BRYOZOA. 377 



tioned by Smitt). This biologic persistence through the ages proves the constancy of 

 the oceanic areas in the Tertiary period. Moreover, the recent species having 

 been discovered fossil in the European Miocene proves that the great equatorial 

 current already existed around the Sargasso Sea. 



This species differs from Hippoporina biporosa in a single ventral avicularium 

 (instead of two oral avicularia), and in a longer aperture (7wz=0.10 mm. instead 

 of 0.08 mm.). 



Occurrence. Upper Jacksonian (Ocala limestone) : West bank Sepulga Eiver; 

 Escambia County, Alabama (rare) ; Alachua, Florida (very rare) ; Bainbridge, 

 Georgia (very rare). 



Vicksburgian (Byram marl) : Byram, Mississippi (rare). 



Vicksburgian (" Chimney rock " of Marianna limestone) : One mile north of 

 Monroeville, Alabama (rare). 



Cotypes.CiLt. Nos. 64073, 64074, U.S.N.M. 



HIPPOPORINA BIPOROSA, new species. 



Plate 49, figs. 1-3. 



Descnption. The zoarium incrusts bryozoa. The zooecia are small, distinct, 

 ovoid; the frontal is convex and smooth. The aperture is small and elongated; the 

 anter nearly circular, is separated by two large cardelles from a poster wide and 

 straight. The ovicell is globular and salient; it is hyperstomial and opens above 

 the aperture. There are one or two small, lateral avicularia placed on the side 

 of the aperture. 



fAa=0. 



Affinities. This species differs from Hippoporina lucens and Ilippoporina 

 cleidostoma in the position of its small oral avicularia disposed on each side of the 

 aperture. 



. Occurrence. Middle Jacksonian (Castle Hayne limestone) : Wilmington, North 

 Carolina. 



Cotypes. Cat. No. 64076, U.S.N.M. 



HIPPOPORELLA, new genus. 



The operculum is much contracted laterally. The cardelles are large. The 

 vanna is much smaller than the porta. The proximal border of the apertura is 

 somewhat concave. The, ovicell is hyperstomial and never closed by the oper- 

 culum. The frontal is bordered by areolar pores. 



Genotype. Hippoporella perforate,, new species. 



Range. Jacksonian-Recent. 



The presence of the areolar pores and of an almost smooth pleurocyst differ- 

 'entiates this genus from Hippoporina Neviani, 1895. The pleurocyst of the ovicell 

 is formed of 3 pieces which are often visible on the fossils. 



