Bulletin - United States National Museum - Smithsonian Institution

32 BULLETIN 96, UNITED STATES NATIONAL MUSEUM.
the zooecia frequently occurring in two forms, a and B^ and provided
with a large operculum armed with teeth, which is suspended
by strong hinge-teeth; the polypide tube is never continued proximally
beneath the cryptocyst cover. (After Levinsen, 1909.)
Genotijye.—Steganoiwrella {Membranipora) magnilabris Hincks,
1880.
Range.—Lutecian-Recent.
Four well-marked new species have been discovered in the Jack-
sonian and Vicksburgian of the Southern States.
Family THALAMOPORELLIDAE Levinsen, 1909.
The tubifer zooecia have calcareous spicula in the shape of com-
passes and bows. The ovicells are hyperstomial, with two calcareous
layers, springing from the whole anter of the apertura; they are
closed by a horizontal cup-shaped chitinized operculum which is
connected at its base with the operculum of the gonozocecium. The
opesiulae are always completely separated from the apertura. The
opercular valve is membranous or chitinized, and more or less com-
pletely separated from the ectocyst by a single or double chitinous
sclerite.
Interzooccial avicularia occur.
Genus THALAMOPORELLA Hincks, 1887.
1887. Thalamoporclla Hincks, Critical Notes ou the Polyzoa, Annals Maga-
zine Natural History (5), vol. 19, p. 104.
Characters same as for the family.
Genotype.—Thalamoporella (Flustra) rozieri Savigny-Audouin,
1812-1826.
Range.—Aquitanian-Recent.
A new species occurs at the top of the Vicksburgian in Mississippi.
Division III. PSEUDOSTEGA Levinsen, 1909.
There are no parietal muscles. The hydrostatic system is external
there is a special hypostege on each zooecium.
The families of this division are:
Membranicellariidae Levinsen, 1909.
Cellariidae Hincks, 1880.
Coscinopleuridae Canu, 1913.
Family CELLARIIDAE Hincks, 1880.
The whole frontal wall of the zocecia is a cryptocyst and they have
a well chitinized, bilaminar, simple operculum with a straight or
concave proximal margin. Within the proximal and sometimes also
within the distal margin of the aperture is placed a pair of (or some-
;