Bulletin - United States National Museum - Smithsonian Institution

50 BULLETIN 9G, UNITED STATES NATIONAL MUSEUM.
ported by a peristomial projection. The frontal is an olocyst per-
forated laterally by some areolae and covered by a uniform pleu-
rocyst.
Genotype.—OchetoseUa jacksonica., new species.
Range.—Claibornian, Jacksonian.
At first glance, this genus appears close to Palmicellaria., but this
is an error. The large avicularian mucro of that genus is replaced
here by a small canal which is evidently the equivalent of the rimulespiramen
of the other genera of the family Stomachetosellidae.
Wlien it exists, the oral avicularium is indeed in its place in the immediate
vicinity of the peristomice and of the rimule-spiramen.
OCHETOSELLA JACKSONICA, new species.
Plate o, fig. 3.
Description.—The zoarium is free, erect, cylindrical, bifurcated,
often anastomosing. The zocecia are elongated, distinct, hexagonal,
separated by a salient thread; the frontal is concave, bordered by
large areolae, formed of a thin olocyst and covered by a uniform and
finely granulated pleurocyst. The apertura is semilunar and invisible
externally; the peristomice is very oblique, with undefined outlines,
vaguely triangular. The ovicell is globular and deeply embedded in
the distal zocecia. The oral avicularium is rare.
Measurements.—Zooecia |^^__q ^q i^m.
Occurrence.—Upper Claibornian (Gosport sand) :
One mile south-
west of Rockville, Clarke County, Alabama (very rare).
Lower Jacksonian : Jackson, Mississippi (very common).
Middle Jacksonian : Wilmington, North Carolina (very common),
and various localities in South Carolina and Georgia.
Type.—Coi. No. G2599, U.S.N.M.
Family SMITTINIDAE Levinsen, 1909.
The ovicell which is hyperstomial and embedded in the distal
zocecia opens into the peristomie. The peristome is produced and
channeled in front. The operculum is (not universally) very thin;
the lower edge is straight or slightly curved inward and hardly
separated from the ectocyst; the muscular attachments are usually
a ridge on the border. There are very small oral glands often partly
attached to the tentacular sheath. Spines.
This family is a very natural one, but unfortunately our knowledge
of the anatomy and embryology is too slight to allow us to fix
its exact limits. The development of the peristome is one of the
essential characters ; we continue to employ the same terminology as
for the preceding families. The orifice of the peristome is the