834 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
Variations . — The great number of peristomes and mesopores which ornament 
the surface of this bryozoan give it a very characteristic porous aspect. Moreover, 
the oval peristomes are unique in the genus. The longitudinal sections which we 
have made are not very clear. They simply indicate the superposition of the multiple 
layers composing the zoarium. The walls of the tubes and mesopores do not appear 
vesicular. 
In its exterior aspect this species much resembles Lichenopora , especially if 
we observe the oval form of the peristomes. But the nature of its ovicell does not 
permit that it be classed with these well-known bryozoa. 
Occurrence . — Middle Jacksonian: Eutaw Springs, South Carolina (common). 
Cotypes. — Cat. No. 65368, U.S.N.M. 
PARTRETOCYCLOECIA EXILIS, new species 
Plate 160, tigs. 5-16. 
Description . — -The zoarium is hollow, cylindrical, bifurcated, with large central 
cavities and thin walls. The tubes are club-shaped in their lower part and cylin- 
drical where the mesopores are developed (in section). The peristomes are thin, 
orbicular, hardly salient, arranged vaguely in very irregular, transverse rows. The 
ovicell is orbicular, somewhat salient, pierced by tubes each of which is accompanied 
by a mesopore. 
M easurements . — • 
Diameter of the peristome. 
Diameter of the mesopores 
Diameter of the ovicell 
Diameter of the branches- 
0.10-0.12 mm. 
0.08 mm. 
1.65 mm. 
3.00 mm. 
Variations . — The peristomes are salient (figs. 9, 10) or not (figs. 11, 12). The 
mesopores are small (fig. 9), medium (fig. 10), or large and polygonal (fig. 12), 
according to the degree of weathering. 
In the longitudinal section it is impossible to confirm the nature of the tubes, 
whether they are cylindrical or club-shaped. 
Affinities . — In its exterior aspect this species much resembles Partretocyclo'ecia 
dumosa Ulrich, 1901. It is distinguished from it only by its micrometric dimen- 
sions, in its smaller ovicell, and in its larger internal cavities. The size of the 
latter is in fact very characteristic. 
Occurrence . — Vicksburgian (Marianna limestone) : One mile north of Monroe- 
ville, Alabama (very common). 
Cotypes. — Cat. No. 65413, U.S.N.M. 
Family ASCOSOECIIDAE Canu, 1919. 
1919. Ascosoeciiclae Canu, Etudes sur les Ovicelles des Bryozoaires Cyclostomes (2), 
Bulletin Soeiete Geologiqne de France, ser. 4. vol. 17. p. 346. 
The ovicell is a large, elliptical, elongate swelling quite salient and perforated 
by the tubes ; often a median oeciopore is present. 
