NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
831 
Measurements . — 
Diameter of the orifices 
Diameter of the mesopores 
Diameter of the branches 
Diameter of the ovicell 
0.08 mm. 
0.07 mm. 
2.20 mm. 
1.10 mm. 
Variations. — This species has been very well described by Ulrich. Even the 
ovicell has been well studied and figured. We have nothing new to add. 
The zoarial cavities are irregular and as they are closed we have supposed that 
they were hydrostatic. 
The adventitious tubes are indeed mesopores and not dactylethrae, for they arise 
in front of normal tubes and not on their dorsal. 
Occurence . — Lowest Eocene (Brvozoan bed at base of Aquia formation) : 
Upper Marlboro, Maryland (very common). 
Plesiotypes— Cat. No. 65239, U.S.N.M. 
PARTRETOCYCLOECIA REPTANS, new species. 
Plate 150, figs. 11-14. 
Description. — The zoarium creeps over bryozoa. It probably gives rise to free 
and hollow fronds. The tubes are club-shaped. The peristomes are orbicular, very 
thin, little salient, irregularly arranged. The mesopores are numerous, polygonal, 
closed by a calcareous lamella. The ovicell is large, orbicular, pierced by the tubes, 
but never by the mesopores. 
Diameter of the peristomes 0.10-0.12 mm. 
Diameter of the orifices 0.08-0.10 mm. 
Diameter of the mesopores 0.06 inm. 
Diameter of the ovicell 2.00 mm. 
Measurements . — 
Affinities. — D’Orbigny classified this zoarial form in Reptomulticlausa. The 
absolute identity of its ovicell with the other species of Partretocycloecia requires 
its classification here. The figured specimen is the only one found. 
Occurence. — Middle Jacksonian: Near Lenuds Ferry, South Carolina (very 
rare) . 
Holotype . — Cat. No. 65373, U.S.N.M. 
PARTRETOCYCLOECIA POROSA, new species. 
Plate 151, figs. 1-6. 
Description — The zoarium is massive, orbicular, formed of many superposed 
layers. The tubes are very short, club-shaped, bent at their extremity (in section) ; 
the peristomes are thin, salient, numerous, elliptical or oval, arranged in quincunx. 
The mesopores are numerous, polygonal, smaller than the peristomes, with non- 
vesicular walls. The ovicell is very large, orbicular, perforated by the tubes, but not 
perforated by the mesopores. 
Diameter of the peristomes 0.16 nun. 
Diameter of the mesopores 0.04-0.08 mm. 
Diameter of the zoaria 10.00 mm. 
Diameter of the ovicell 0.35-0.38 mm. 
M easurements . — 
