NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
107 
M easurements . — Opesium 
| Ac* =0.12 mm. 
|Z?=0.10 mm. 
Zooecium 
|Zs=0.25 mm. 
[ lz— 0.20-0.27 mm. 
Vibraculum 
|Z-y=0.25 mm. 
^=0.10 mm. 
Variations .- — The lines of zooecia are easily detached from one another. Their 
edge (fig. 16) shows a minutely furrowed surface in which the furrows radiate 
from the same center of origin as the lines. As is indicated in figures 11, 12, 13 
this center of origin is not necessarily the zoarial center. These furrows represent 
intercostal canals which are independent of the perforating tubules (fig. 19), the 
orifices of which are visible at t in fig 16. This same figure shows ajso the large 
multiporous lateral septulae. 
In sections (fig. 19) the zooecia are urceolate, erect, separated by convex par- 
titions. In the same radial line they communicate among themselves by means of 
a large distal septula (s. cl.). The tubules ( t ), corresponding to the large pores of 
the inner face, probably serve for the passage of the mesenehymatous network. 
In small zoaria the ribs of the inner face are hollow at their extremities (figs. 
13, 14, 15). These hollow spaces were subsequently filled up, for the sections do not 
indicate these cavities (fig. 19). 
The proliferation of the zooecia is not always regular about the ancestrula (fig. 
14). A flabelliform colony (fig. 13) is often formed and becomes discoidal by 
special budding at the ends and on the sides of the lines of zooecia. The tangential 
section (fig. 17) is not very well oriented, but it is sufficient to show the constitu- 
tive elements of the olocyst grouped in radial lines about the opesium. 
Affinities. — This species differs from OtioneTla tuberosa in the numerous pores 
which perforate its inner face. The opesial collar is analogous to that which Levin- 
sen has noted in M embranicellaria ; but we have never observed the endotoichal ovi- 
cell of this genus. 
Occurrence. — Claibornian (Gosport sand) : Claiborne, Alabama (common) ; 
Gopher Hill, Tombigbee River, Alabama; 1 mile southeast of Rockville, Clarke 
County, Alabama (common). 
Claibornian (Lisbon formation) : Wautubbee Hills, 4 miles south of Enterprise, 
Mississippi ( rare ) . 
Lower Jacksonian ( Moodys marl) : Jackson, Mississippi (common). 
Cotypes . — Cat. No. 62571, U.S.N.M. 
OTIONELLA TUBEROSA, new species. 
Plate 12, figs. 5-15. 
D escription. — The zoarium is discoidal, with a concave inner face. The zooecia 
are hexagonal, somewhat indistinct, joined by their mural rims, disposed apparently 
in irregular quincunx; the mural rim is concave, broad, especially at the base. The 
opesium is elliptical or nearly orbicular and bordered by a prominent collar. The 
vibraculum is interzooecial, asymmetrical, auriculated, larger than the zooecium. 
