144 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
nature of its mural rim also are as in Antropova Norman, 1903; but species of this 
genus are provided with avicularia. To be exact, it would be necessary to create a 
new genus, but as we possess only the single specimen figured, we think it prudent 
to await for more abundant material. 
Occurrence. — Wilcoxian (Bashi formation) : Woods Bluff, Alabama (very 
rare). 
Holotype.— Cat. No. 63833, U.S.N.M. 
ALDERINA PULCHERRIMA, new species. 
Plate 29’, fig. 1. 
Description. — The zoarium is free, unilamellar, creeping over algae. The 
zooecia are large, elongated, elliptical; the mural rim is broad, concave, smooth, 
enlarged below. The opesium is elliptical, elongated, entire. The ovicell is hvper- 
stomial and never closed by the opercular valve, is globular, very salient, distinct 
from the mural rim, furrowed in front; it is formed of two calcareous lamellae of 
which the exterior one is of the same nature as the mural rim. 
M easurements . — Opesia 
|/m=0.80 mm. 
1 70=0.50 mm. 
Zooecia 
Lz= 1.20 mm. 
73=0.80 mm. 
This very beautiful species has no related form either fossil or living. 
Occurrence. — Middle Jacksonian: Wilmington, North Carolina (very rare); 
near Lenuds Ferry, South Carolina (very rare). 
Lower Jacksonian (Moodys marl) : Jackson, Mississippi (very rare). 
Holotype. — Cat. No. 63918, U.S.N.M. 
ALDERINA LUNATA, new species. 
Plate 29, fig. 5. 
Description. — The zoarium incrusts bryozoa. The zooecia are distinct, sepa- 
rated by a deep, somewhat elongated, oval furrow; the mural rim is very thin 
distally, somewhat enlarged proximally, granulated. The opesium is elongated, 
elliptical, or oval, and very finely crenulated. The ovicell is globular, salient, and 
transverse; the frontal area is in the form of a crescent and granulated like the 
mural rim. 
M easurements . — Opesia 
17*0=0.30-0.32 
1/0=0.22-0.25 
mm. 
mm. 
Zooecia 
| A, 3=0.40— 0.50 mm. 
1 7? =0.25-0.30 mm. 
Affinities. — This species differs from the recent Alderina imbellis Hincks, 1860, 
in the less length of its ovicell (0.15 instead of 0.20 mm.) and its frontal area, 
which is in the form of a crescent instead of being rectangular. These differences 
are insignificant, for the micrometric measurements are identical, and they occur 
almost within the possibilities of the habitual variations of a species. If we have 
created a distinct species it is because Alderina imbellis has never been found 
fossil, and because such a sudden appearance in the Lower Eocene seems to us too 
unusual. 
A more closely related species is Alderina irregularis Smitt, 1872, in which the 
micrometric dimensions are also identical. It differs from it simply in its crescent 
