NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
387 
Occurrence. — Middle Jacksonian: Wilmington, North Carolina (very com- 
mon) ; 31 miles south of Perry, Georgia (rare) ; 3f miles north of Grovania, Georgia 
(very rare). 
Upper Jacksonian (Ocala limestone) : Alachua, Florida (rare) ; West bank of 
Sepulga River, Escambia County, Alabama (rare). 
Jacksonian (Zeuglodon zone) : Shubuta, Mississippi (rare). 
Cotypes.— Cat. No. 64083, U.S.N.M. 
HIPPOMENELLA RADICATA, new species. 
Plate 50, figs. 19-24. 
Description. — The zoarium is unilamellar and creeps over algae; the lower 
face presents some elongated zooecia, smooth or striated transversally and regularly 
perforated by a radicular ( ?) pore. The zooecia are elongated, distinct, oval, sepa- 
rated by a furrow ; the frontal is smooth, convex, garnished laterally by a double 
row of triangular areolae often separated by short pleurocystal costules. The 
aperture is elongated, elliptical, provided with two very small cardelles ; , it is 
'surrounded by a peristome little salient, garnished with 6 large spines; there is a 
vestibular arch. The ovicell is globular, salient, hyperstomial, embedded in the 
distal zooecia, never closed by the operculum; the two areas are smooth or punctate. 
The avicularia are placed below the aperture; they are salient, triangular, the beak 
pointed toward the bottom, rarely symmetrical. 
Measurements. — Aperture 
\ha= 0.16 mm. 
[Za=0.14mm. 
Zooecia 
\Lz=0.l0 mm. 
lfe=0.36-0.40 mm. 
Variations. — The areas of the ovicell are not always visible and are replaced 
by punctations (fig. 20). Of the two avicularia there is one almost always larger 
than the other; nevertheless symmetry is possible (fig. 22). The dorsal perforation 
is placed just below the aperture; it corresponds perhaps to some radicells as in 
the genus Petralia MacGillivray, 1881, it is rather constant; nevertheless we have 
some specimens which are deprived of it. The interareolar costules are absent or 
accentuated (fig. 21). 
Schisoporella geminipora Reuss, 1867, and Ilippoporina perforata are also 
provided with pores on the under side as in the genus Petralia MacGillivray, 1881. 
But the nature of their ovicell, never closed by the operculum, does not permit 
their arrangement in this genus. 
Affinities. — This species differs from Hippomenella alifera in its less promi- 
nent and nonsymmetrically placed avicularia, in its larger interareolar costules. its 
smaller micrometric dimensions, and in its dorsal radicular pores. 
It differs from Hippomenella transversora in its elongated aperture (and not 
transverse) and in the absence of a labial convexity at the aperture. 
It differs from Hippomenella punctata in which the ovicell is porous in its 
smaller micrometric dimensions ( = 0.70 mm. and not 1.00 mm.) and in its free 
and nonincrusting zoarium. 
