NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
825 
r 
Measurements . — 
Diameter of the peristome 0.12 mm. 
Interior diameter of the tubes (section) 0.06-0.08 mm. 
Maximum diameter of the branches 1.8 mm. 
Diameter of the mesopores 0.61 mm. 
Diameter of the ovicell 1.35 mm. 
Affinities. — Exteriorly this species, much resembles Leiosoecia parvicella Gabb 
and Horn, 1860, from the Cretaceous of New Jersey; it differs from it in its club- 
shaped tubes, its hollow zoarium, and in its larger and more globular ovicell. 
Fig. 274.- — Parleiosoecia, now genus. 
A-C. Parleiosoecia jaclcsonia, new species. A. Ovieelled branch, X 12, showing the smooth 
ovicell. B. Transverse section, X 12. C. Vertical section, X 12. 
Middle Jacksonian of South Carolina. 
B x 12 
It appears' rather close to Heteropora subreticulata Eeuss, 1869, from the 
Priabonian of Vicentin, but it differs from it in the exterior form of the mesopores. 
The interior of the branches presents (fig. 13) a successive series of rather regular 
constrictions, the utility of which is not yet known. They do not correspond to 
the form of an internal substratum, for the branches are naturally hollow and 
closed at their extremities. These internal cavities are often traversed by very 
convex diaphragms (fig. 12). 
At the ramifications the walls of the mesopores cease to be vesicular, trans- 
forming themselves thus into firmatopores or canals of reinforcement. 
O ccurrence. — Middle Jacksonian. Wilmington, North Carolina (rare) ; near 
Lenuds Ferry, South Carolina (rare) ; Eutaw Springs, South Carolina (very com- 
mon) ; 18 miles west of Wrightsville, Johnston County, Georgia (very rare) ; Kieli 
Hill, 5£ miles southeast of Knoxville, Crawford County, Georgia (rare) ; 17 miles 
northeast of Hawkinsville, Georgia (very common). 
Cotypes. — Cat. Nos. 65446-65451, U.S.N.M. 
