NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
241 
thinner along the sides, the anterior end appearing to be overlapped by the posterior 
ridge of the next succeeding zooecium. Aperture surrounded by a thickened rim, 
generally rounded in front and straighter behind, sometimes subquadrate, its 
anterior border close to the prominent end of the next cell, and the length and 
width averaging about half the corresponding dimensions of the entire zooecium. 
Vibracular cells fusiform or elongate oval, rather large, one usually at each 
angle of junction between four zooecia. A constriction occurs near the center of 
each, sometimes on one side only, at other times on both. A narrow area may 
surround the opening. Under surface marked by irregular depressed lines radiat- 
ing from the narrow lower extremity of the zoarium. Between these lines the 
surface is convex and rather coarsely pitted and granulate. (After Ulrich.) 
The vibraculum is symmetrical and has two lateral condyles. The figured 
specimen has no opesiular indentations. However, the presence of the calcified 
cryptocyst is an indication that the parietal muscles are really attached to the 
ectocyst. 
Occun-ence. — Lowest Eocene (Bryozoan bed at base of Aquia formation) : 
Upper Marlboro, Maryland (rare). 
Plesiotype. — Cat. No. 63799, U.S.N.M. 
LUNULARIA OVATA, new species. 
Plate 9, figs. 11, 12. 
Description.- — The zoarium is a slightly convex Lunulites, bearing at the center 
a large number of hydrostatic zooecia. The polypidian zooecia form the four or 
five exterior, circular rows ; they are hexagonal, little distinct, elongated ; the mural 
rim, smooth and thick, is distinct from the little developed cryptocyst ; the opesium 
is elongated, oval , the narrow end in front, entire. The ovicell is a small, indistinct 
distal convexity. The vibracula are arranged in distinct and regular rows; they 
are interzooecial, symmetrical, fusiform, without lateral condyles. On the inner 
side the ribs are disposed in longitudinal series under the hydrostatic zooecia and 
in radial series under the polypidian zooecia. They are furnished with many rows 
of tuberosities. 
M easurements. — Opesia 
|7ic»=r0.15mm. 
\lo=0.V2 mm. 
Zooecia 
Lz— 0.25 mm. 
fe=0.23 mm. 
Vibracula 
Lv= 0.25-0.30 
Iv =0.1 6 mm. 
mm. 
Affinities. — This species is the American representative of Lunularia radiata 
Lamarck 1818, a common species in the Parisian Lutetian, but it is much smaller 
in zooecial dimensions. 
It differs from Limularia verrucosa in its oval opesium and in the large 
tuberosities which ornament the sides of the inner face. 
Occurrence. — Wilcoxian (Bashi division) : Woods Bluff, Alabama (rare). 
Cotypes. — Cat. No. 63834, U.S.N.M. 
55899— 19— Bull. 106- 
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