452 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Stomachetosellidae. When it exists, the oral avicularium is indeed in its place 
in the immediate vicinity of the peristomice and of the rimule-spiramen. 
OCHETOSELLA JACKSONICA Canu and Basslcr, 1917. 
Plate 15, figs. 1-10. 
1917. Ochetosella jaclcsonica Canu and Bassler, Synopsis American Early Tertiary Cheilo- 
storne Bryozoa, Bulletin 96, United States National Museum, p. 50, pi. 5, tig. 3. 
Description . — The zoarium is free, erect, cylindrical, bifurcated, often anasto- 
mosing. The zooecia are elongated, distinct, hexagonal, separated by a salient 
thread; the frontal is concave, bordered by large areolae, formed of a thin olocvst 
and covered by a uniform and finely granulated pleurocvst. The apertura is semi- 
lunar and invisible externally; the peristomice is very oblique, with undefined 
outlines, vaguely triangular. The ovicell is globular and deeply imbedded in the 
distal zooecia. The oral avicularium is rare. 
M easurements . — Zooecia 
\Lz= 1.10-1.20 mm. 
[Zs=0.50 mm. 
V aviations. — The young zooecia have no separating thread (figs. 3-6) ; they 
have a mucro much developed and quite prominent (figs. 4, 5) which bears the 
characteristic small canal. The zooecia are thickened by the development of the 
pleurocyst which is deposited at first around the areolae (fig. 9) and afterwards 
over all the frontal (fig. 8). In these conditions, the mucro is of less and less 
prominence, but the small canal- like spiramen always persists. This same pleurocyst 
covers the ovicell (figs. 3, 10). 
At the bifurcation of the branches, there is a large zooecium which bears a 
large special avicularium whose purpose is still to be learned. 
Affinities. — This species is very easy to determine. It differs from O chetosella 
robusta in its smaller zoarium, in its large, lateral areolae and in the absence of 
the zooecial peristomie. 
Occurrence. — Upper Claibornian (Gosport sand) : One mile southwest of 
Rockville, Clarke County, Alabama (very rare) ; Gopher Hill, Tombigbee River. 
Alabama (rare). 
Lower Jacksonian (Moodvs marl) : Jackson, Mississippi (very common). 
Middle Jacksonian: Wilmington, North Carolina (very common) ; near Lenuds 
Ferry, South Carolina (common) ; Eutaw Springs, South Carolina (common) ; 
3J miles south of Perry, Georgia (common) ; 18 miles west of Wrightsville, Georgia 
(common) ; Rich Hill, Crawford County, Georgia (very common) ; Baldock, Barn- 
well County, South Carolina (very common) ; 17 miles northeast of Hawkinsville, 
Georgia (rare) ; one-half mile southeast of Georgia Kaolin Company mine, Twiggs 
County, Georgia (rare). 
Upper Jacksonian (Ocala limestone) : West bank Sepulga River, Escambia 
County, Alabama (rare). 
Cotypes. — Cat No. 62599, U.S.N.M. 
