NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
249 
Affinities. — The vibracula are arranged two to every two zooecia ( Oligotresium 
of Gabb and Horn) in which feature the species agrees with Lunularia, contigua 
Lonsdale, 1845, and L. vicksburgensis Conrad, 1847. 
It differs from Lunularia contigua in its solid zoarium without ' hydrostatic 
zoarial cavity (fig. 13). 
It may be distinguished from Lunularia vicksburg ensis Conrad, 1847, by its 
vibracular condyles which are without depressions, by its opesial, proximal border 
which is often convex, by the pores of the rows on the inner face which are much 
more numerous and closer together, and by its smaller zooecial dimensions. 
Occurrence.— Claibornian (Gosport sand) : One mile southwest of Rockville, 
Clarke County, Alabama (common) ; Gopher Hill. Tombigbee River, Alabama 
(common); Claiborne, Alabama (rare). 
Cotypes. — Cat. No. 63847, U.S.N.M. 
LUNULARIA (OLIGOTRESIUM) VICKSBURGENSIS Conrad, 1847. 
Plate 83, figs. 1-11. 
1847. Lunulites vicksburg ensis Conrad, Observations on tbe Eocene formation, and descrip- 
tions of one hundred and five new fossils of that period, from the vicinity of Vicks- 
burg, Mississippi, with an appendix, Proceedings Academy Natural Sciences Phila- 
delphia, vol. 3, p. 296; idem 1848, Journal Academy Natural Sciences Philadelphia, 
ser. 2, vol. 1, p. 127. 
1862. Oligotresium vicksburgensis Gabb and Horn, Monograph of the fossil polyzoa of 
the Secondary and Tertiary formations of North America, Journal Academy Natural 
Sciences Philadelphia, ser. 2, vol. 5, p. 139, pi. 19, fig. 22. 
Description. — The zoarium is a convex expanded Lunulites, without hydrostatic 
zooecia. The zooecia are distinct, ogival, somewhat transverse ; the mural rim is 
very thick ; the cryptocyst is very small and finely granulated. The opesium is oval, 
narrowest at the top, the proximal border quite concave; it is bordered by a small 
collar. The ovicell is a distal convexity hidden by the external calcification. The 
vibraculum is very long; its opesium is large and narrowed in the upper third 
by two large condyles with a small fossette. The vibracula are arranged in radial 
rows, but there is only one to every two interzooecial angles. On the inner side the 
radial lines are convex and garnished with large scattered pores. One pair of 
lateral septulae. 
« fAo=0.20mm. ,, ■ , . \Lz=0. 35 mm. 
Measurements . — Opesium 7 „ AAtr Marginal zooecium 7 . 
1 [Zo==0.20-0.25mm. inii!a7j!^ytei- L L^; .|lfe=0.35mm. 
.. fZ'P=:0.35mm. 
Vibraculum , A OA 
[lv=0.20 mm. 
A? aviations . — The micrometric dimensions of the zooecia and opesia are quite 
variable and are notably larger on the zoarial margins. The ectocvst which floats 
in the hypostege secretes a thin calcareous granular laver ; which is deposited chiefly 
on the primitive- olocyst of the cryptocyst and ovicell (fig. 2). 
The vibraculum is not always elliptical; it has sometimes a distal callosity 
in the form of the leaf of Sagittaria (fig. 3). 
