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. 



Occurrence. 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. 



!/io=0.15 mm. . \Lz 0.25mm. 



\ lo=012 mm Zooecia | fe=0 2g mm> 



, fZfl=0.25-0.30 mm. 

 Vibracula \ 7 nie 



\t'=0.16 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 Lunularia 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.Cai. No. 63834, U.S.N.M. 

 55899 19 Bull. 106 16 



