310 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
tical, and are followed by large (fig. 10) or smaller (figs. 11, 13) lacunae, which 
vary in number, although there are always at least two. 
The tangential sections show very clearly the existence of a lumen and of large 
lumen pores (fig. 12). 
Affinities. — This species differs from the recent Acanthocella tubulifera Hincks, 
1881, in its larger number of lumen pores (3 or 1 instead of 2). 
It differs from Gribrilina suggerens Waters, 1881, in its zoarium, which is not 
bilamellar and in its larger micrometric dimensions (Za=0.12 mm. and not 
0.06 mm. ) . 
Occurence. — Middle Jacksonian (Castle Hayne limestone) : Wilmington, North 
Carolina (rare). 
Cotypes. — Cat. No. 62587, U.S.N.M. 
Genus CRIBRENDOECIUM Canu and Bassler, 1917. 
1917. Cribrendoecium Canu and Bassler, Synopsis of American Early Tertiary Cheilo- 
stome Bryozoa, Bulletin 96, United States National Museum, p. 36. 
The ovicell is endozooecial. The costules are separated by a small initial slit 
and some medium-sized lacunae ; they have no lumen pores. The aperture is formed 
of a semilunar anterior portion and a larger and concave posterior part separated 
by two cardelles. The aperture of the ovicelled zooecia is larger. Large inter- 
zooecial avicularia are present. , 
Genotype.— Cribrendoecium tenuicostulatum Canu and Bassler, 1917. 
This genus shows the closest resemblance to Hippopodina Levinsen, 1909, in the 
nature of its ovicell and its oral dimorphism. On the other hand, its interzooecial 
avicularia and the structure of its ovicell marked with two lateral cicatrices, relate 
it to Figularia Jullien, 1880. It is therefore very probable that the species of Cri- 
brendoecium are provided with a compensatrix, just as in the two genera cited and 
as the nature of its aperture would predict. 
CRIBRENDOECIUM TENUICOSTULATUM Canu and Bassler, 1917. 
Plate 43, fig. 8. 
1917. Cribrendoecium tenuicostulatum Canu and Bassler, Synopsis of American Early 
Tertiary Cfieilostome Bryozoa, Bulletin 96, United States National Museum, p. 36, 
pi. 4, fig. 1. 
Description. — The zoarium incrusts shells. The zooecia are distinct, elongated, 
separated by a furrow, elliptical, fusiform; the frontal is convex; the costules are 
very thin , numerous, without lumen pores, and separated by very small lacunae. 
The apertures of the ordinary zooecia are formed of a semilunar anterior and a 
very large, straight posterior part separated by two small cardelles; the aperture 
of the ovicelled zooecia is larger and its posterior portion is convex. The ovicell 
is endozooecial and exteriorly is prominent and transverse; it is formed of two 
calcareous deposits; the outer one is incomplete and leaves two lateral cicatrices 
in the form of a cross. The avicularia are interzooecial and are elongated, spatu- 
late, perforated by a long slit and generally without pivot. 
