NORTH 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 Ilippoporina biporosa in a single ventral avicularium 
(instead of two oral avicularia), and in a longer aperture (Aa=0.10 mm. instead 
of 0.08 mm.). 
Occurrence . — Upper Jacksonian (Ocala limestone) : West bank Sepulga River; 
Escambia County, Alabama (rare) ; Alachua, Florida (very rare) ; Bainbridge, 
Georgia (very rare). 
Yicksburgian (Byram marl) : Byram, Mississippi (rare). 
Vicksburgian (“ Chimney rock ” of Marianna limestone) : One mile north of 
Monroeville, Alabama (rare). 
Cotypes. — Cat. Nos. 64073, 64074, TJ.S.N.M. 
HIPPOPORINA BIPOROSA, new species. 
Plate 49, figs. 1-3. 
Description . — 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. 
Measurements . — Aperture 
lia— 0.10 mm. 
la= 0.07 mm. 
Zooecia 
Z^=0.40 mm. 
fe=0.28-0.30 mm. 
Affinities . — This species differs from Ilippoporina 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. — TlippoporeMa perforata , new species. 
Range. — Jacksonian-Recent. 
The presence of the areolar pores and of an almost smooth pleurocyst differ- 
entiates this genus from Ilippoporina Neviani, 1895. The pleurocyst of the ovicell 
is formed of 3 pieces which are often visible on the fossils. 
