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BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
by a smaller circular lacuna. The aperture is suborbicular with a concave lower lip. 
The ovicell is enormous, globular, very prominent, pierced with small pores widely 
spaced. The ovicelled zooecia bear at the right and left of the aperture two large, 
symmetrical lamellae forming a sort of peristomie. The operculum never closes the 
ovicell. On each zooecium there are one or two large, oval avicularia very promi- 
nent and triangular, with a pivot, the point turned toward the aperture. 
Measurements . — Aperture 
<2= 0.2 9 mm. 
Ua=0.25 mm. 
Zooecia 
Zs= 1.00-1.10 mm. 
lz =0.45 mm. 
Variations . — -The more or less complete arch which is formed above the aper- 
ture of the ovicelled zooecia is evidently designed to facilitate the passage of the 
eggs and is a pseudo peristomie. The small lacuna is not always present (figs. 
11, 12) ; the aspect is then that of a true M embraniporella, On the old zoaria 
(fig. 11) the gymnocyst is thickened and shows a mural rim around the cribriform 
area. 
In this species the lateral clefts are the intercostal spaces. In figure 12 notably 
the lumen is clearly visible in the costules and in the broken zooecia. The costules 
appear to be hollow. 
We note again that the operculum does not close the ovicell as in the other 
species of the genus. 
In the future it may be necessary to classify this species in the genus C orbulipora 
MacGillivray, 1895, when we are better acquainted with the structure of that genus. 
Affinities . — This species is very close to M embraniporella agassizi Smitt, 1873, 1 
which lives to-day in the Gulf of Mexico and in the waters off Florida. It is dis- 
tinguished by the absence of a transverse rib on the ovicell, by the different form 
of the avicularia and the larger micrometric dimensions (£<2=0.25 mm. and not 
0.16 mm.). 
The genus Corbulipora is a member of the Cribrilinidae with a vincular 
zoarium, but quadriserial. In our species the zooecia are in six series and appear 
to differ otherwise generically. 
It is moreover quite remarkable to find in the Eocene species almost identical 
with those now living off the coast of Florida. This is proof of the calm tectonic 
conditions in this region during all the Tertiary period. 
Occurrence . — Yicksburgian (“Chimney rock” of Marianna limestone): One 
mile north of Monroeville, Alabama (common). 
Cotypes. — Cat. No. 61258, U.S.N.M. 
Genus CRIBRILINA Gray, 1848. 
1848. Crtttrilina Gray, List British Animals in British Museum, pt. 1, Centroniae, p. 116. 
Bibliography (Anatomical) . — 1894. Levinsen, Zoologica daeica, p. 61, pi. 5, figs. 7-22. — 1900. 
Watebs, Bryozoa from Franz Joseph Land, Linnean Society Journal, Zoology, vol. 28, p. 52, 
pi. 8, figs. 21, 22. — 1903. Norman, Notes on the Natural History of East Finmark, Annals 
Magazine Natural History, ser. 7, vol. 12, p. 93, pi. 8, fig. 10. — 1909, Levinsen, Morphological 
and Systematic Studies on the Cheilostomatous Bryozoa, p. 158, pi. 9, fig. 11. 
1 1875, Smitt, Floridan Bryozoa, Kongl. Svenska Vetenskaps-Akademiens Handlingar, vol. 10, p. 11, 
pi. 5, figs. 103-106. 
