386 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
O ccuiTence . — -Vicksburgian j(“ Chimney rock ” of Marianna limestone) : One 
mile north of Monroeville, Alabama (very common). 
Vicksburgian (Red Bluff clay) : Seven and one-half miles southwest from 
Bladen Springs, Alabama (common). 
Cotypes.— Cat. No. 64273, U.S.N.M. 
Group 2. ZOARIUM UNILAMELLAR (Semieschara). 
HIPPOMENELLA ALIFERA, new species. 
Plate 50, figs. 9-18. 
Description . — The zoarium is unilamellar and creeps over algae. On the inner 
face in contact with the substratum the zooecia are convex, hexagonal, formed of 
an olocyst covered by a pleurocyst and often ornamented by hydrostatic tuberosi- 
ties. The zooecia are elongated, distinct, hexagonal or oval ; the frontal is convex, 
smooth, surrounded by two or three rows of small and numerous areolae. The 
aperture is elliptical, elongated; the peristome very little salient, bears six large 
spines; two small cardelles separate a large anter from a smaller poster. The 
ovicell very large, very prominent, globular, and smooth, is hyperstomial and little 
embedded in the distal zooecia ; a small median nerve separates the two areas. The 
avicularia are very large and salient; they are placed below and close to the aper- 
ture; their beak is triangular and directed obliquely toward the bottom; they have a 
calcareous pivot. 
Measurements . — Aperture 
| A«=0. 18-0.20 mm. 
1 7u=0.14-0.16 mm. 
Zooecia 
Zs=0.70-0.80 mm. 
7s=0.40-0.60 mm. 
Variations . — This species represents the height of polymorphism ; there is not 
a single specimen comparable with another and not a single zooecium resembles its 
neighbor. 
The areolae are often disposed' in two or three rows (figs. 10, 13). sometimes 
spreading over all the frontal (fig. 11) and becoming true tremopores. The avicu- 
laria may be short and unsymmetrically disposed (fig. 10), but are generally very 
large and very salient, like extended wings (figs. 11, 14). The ovicells, globular 
(fig. 13) or pyriform (fig. 11), are almost always smooth. 
The lower face of the zoarium is smooth (fig. 15) ; each dorsal is formed of 
two separable calcareous layers (fig. 16), a pleurocyst on an integral olocyst; the 
hydrostatic tuberosities are rare but may become very large (fig. 17). The zoa- 
rium may be incrusting. 
In the interior the apertura shows a porta larger than the vanna, separated 
by two cardelles (fig. 8). 
Affinities . — Its smooth ovicells and large avicularia characterize this species 
rather well. It differs from IUppomenella radicata in its larger aperture, its 
smooth ovicell, it avicularia symmetrically disposed, and in its dorsal not regularly 
perforated. 
It differs from HippomeneTla transversata in its elongated aperture (and not 
transverse), in its more salient avicularia and more than two rows of lateral areolae. 
