NORTH AMERICAN EARLY TERTIARY BRYOZOA. 831 



Measurcmcn ts. 



Diameter of the orifices 0.08 mm. 



Diameter of the mesopores 0.07 mm. 



Diameter of the branches 2.20 mm. 



Diameter of the ovicell 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. 



Oceurence. Lowest Eocene (Bryozoan bed at base of Aquia formation) : 

 Upper Marlboro, Maryland (very common). 

 PlesiotypesCat. 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 mm. 



Diameter of the ovicell 2.00 mm. 



Affinities. D'Orbigny classified this zoarial form in Reptomulticlausa. The 

 absolute identity of its ovicell with the other species of Partretocydoecia requires 

 its classification here. The figured specimen is the only one found. 



Occurrence. Middle Jacksonian: Near Lenuds Ferry, South Carolina (very 

 rare). 



Holotype.Czt. No. 65373, U.S.N.M. 



PARTRETOCYCLOECIA POROSA, new spcries. 



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 mm. 



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. 



Measurements. 



