NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
133 
Examples of total regeneration are very rare. 
Affinities. — The termen of the mural rim sometimes becomes very sharp and 
crenulated (fig. 10). 
This species is quite similar to Grammella crassimarginata, differing only in its 
small dimensions. It is not a variety because it occurs at different localities. 
Occurrence. — Middle Jacksonian: IS miles west of Wrightsville, Johnson 
County, Georgia (very rare). 
Upper Jacksonian (Ocala limestone) : West bank of Sepulga River, Escambia 
County, Alabama (rare) ; Chipola River, east of Marianna, Jackson County, 
Florida (rare) ; 1| miles above Bainbridge, Georgia (rare). 
Vicksburgian (“ Chimney rock ” of Marianna limestone) : One mile north of 
Monroeville, Alabama (rare). 
Cotypes. — Cat. Nos. 63898, 63899, U.S.N.M. 
Genus MEMBRANIPORIBRA Canu and Bassler, 1917. 
1917. M embran iporidra Canu and Bassler, Synopsis of American Early Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 21. 
The operculum always closes the ovicell. No dietellae. No avicularia. One 
large distal septula; two pairs of lateral septulae. 
Genotype. — M ern b raniporidra porrecta Canu and Bassler, 1917. 
Range.- — Jacksonian and Vicksburgian. 
The ovicell is deeply excavated in the distal zooecium. It is only by dissection 
that we are able to prove by the continuity of the mural rim, although very thin 
distally, that the ovicell is indeed hyperstomial. The mural rim is always enlarged 
at the base and finely granular. 
This genus differs from Alderina Norman, 1903, not only in the closure of the 
ovicell by the opercular valve, but also in the absence of dietellae. 
It is probable that many recent species may be included in this genus. The 
most common form among them might well serve as the true genotype. 
MEMBRANIPORIDRA OECIOPOROSA, new species. 
Flute 26, figs. 1, 2 
Description. — The zoarium incrusts shells. The zooecia are elongated, distinct, 
elliptical; the mural rim is slightly salient, curved, enlarged at the base, where it 
has two lateral furrows, ornamented with very small granulations radially ar- 
ranged. The opesium is elliptical. The ovicell is large, globular, salient, orna- 
mented with a frontal callosity, the wall of which, lying on the distal part of the 
zooecium, is finely porous. 
Measurements. — Opesia 
[fio= 0.22-0.25 mm. 
|7u=0.15-0.l7 mm. 
Zooecia 
| L, 3=0.35 mm. 
I lz— 0.23-0.25 mm. 
Variations . — This species is very irregular is its gemmation, and deformed 
zooecia are numerous. The ovicell is interesting for its peculiarities — a fragile, 
frontal callosity and finely porous floor. The callosity is finely granular like the 
