NORTH AMERICAN EARLY TERTIARY BRYOZOA. 387 



Occurrence. Middle Jacksonian : Wilmington, North Carolina (very com- 

 mon) ; S\ miles south of Pcrr}'. Georgia (rare) ; 3 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.G&t. 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 transversallv 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. 



,, [M=0.16mm. . fZ0=0.70mm. 



measurements. Aperture \ 7 n .. Zooecia , ~ 



Ua=0.14 mm. 1^=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). 



Schizoporella geminipora Reuss, 1867, and Hippoporina 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 tra.mversora 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. 



