Bulletin - United States National Museum - Smithsonian Institution

EARLY TERTIARY CHEILOSTOME BRYOZOA. 73
base 2 cm. 5 mm. in width. The zooecia are disposed in two groups,
back to back and inseparable. The axial zocecia back to back are
oriented; all the other zooecia are cumulate. The superficial zooecia
are distinct, urceolate, little raised, very oblique ; the frontal is quite
convex, smooth, bearing 0-3 improminent avicularia with pivot ; the
frontal is formed of a very thick olocyst. The apertura is oval,
deeply imbedded at the base of a peristomie; the peristomice is ir-
regular, suborbicular. The deep zooecia haA^e a flat frontal; their
avicularia are prominent between the superficial zooecia. The inter-
zoa'cial avicularia are distinct, elliptical, of the size of zooecia;
they have a pivot; their orifice is like the beak of a duck; the pas-
sage of the reflexor muscles of the operculum is indicated by the very
small perforations on the inferior cavity ; the beak is salient above the
zoarium. The incomplete zooecia are quite numerous. On many
zoaria there are some distinct groups of large zooecia and of small
zooecia.
(ha=0.1i) mm.
Measure7nents.—Apertura (interior) j ^^^ _q -j^^j ^^^^^^
fZs=0.60mm.
Zocecia j^^ =0.30-0.35 mm.
Variations.—Following the rule, the variations of these Cellepores
are quite great, but the species is always rather easy to determine by
its zoarial size.
Occurrence.—Lower Jacksonian: Jackson, Mississij^pi (common).
Middle Jacksonian: "Wilmington, North Carolina (common); 3^
miles south of Perry, Georgia (common).
Upper Jacksonian: Cocoa post office, Choctaw County, Alabama
(very common).
Vicksburgian : 7| miles from Bladen vSprings, Alabama (rare);
Bed Bluff, Wayne County, Mississippi (rare).
Type.—Q2it. No. 62613,' U.S.N.M.
Family CONESCHARELLINIDAE Levinsen, 1909.
The zocecia are erect; the apertura is terminal. The gemmation
is always and uniquely lateral. The ovicell is hyperstomial and
recumbent. There is a zooecial and a zoarial hydrostatic system.
This is a very mysterious group A^Iiich has given the zoologists
much trouble. Only Maplestone in 1910 ^ has given some details
on the zoarial life.
Almost all our specimens belong to a new American genus
Schizorthosecos.
' 1910. Maplestone. On the Growth and Habits of Biporae, Proceedings Royal Society
Victoria, vol. 23.