NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



765 



Affinities. This species differs from Erkosonea semota in the lesser distance of 

 the fascicles from each other and in the presence of the radicular lamellae. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (very com- 

 mon) ; near Lenucls Ferry, South Carolina (rare) ; Eutaw Springs, South Carolina 

 (rare). 



Upper Jacksonian (Ocala limestone) : West bank Sepulga River, Escambia 

 County, Alabama (rare). 



Coti/pcs.Cnt. No. 65357, U.S.N.M. 



PLEURONEA, new genus. 



Greek : pleuron, side, referring to the position of the ovicell. 

 ' The ovicell is situated laterally on one-half of the basal lamella and between 



the fascicles on a single side of 

 the median axis. The oeciopore 

 appears to be the first tube of a 

 fascicle. The basal surface is 

 provided with large tergopores 

 generally imperfectly oriented. 

 The zooecia are grouped in fas- 

 cicles, arranged symmetrically 

 on each side of the zoarial axis. 

 Genotype. Idmonea fenes- 

 trata Busk, 1859. 



Range. Midwayan-Astian. 

 This genus differs from 

 Mesonea not only in the lateral 

 position of the ovicell but also in 

 the nature of the canals which 

 reinforce the basal lamella. If 

 one can generalize Busk's figure, 

 1859, these canals would be closed at their extremity by a calcareous, porous 

 lamella extremely fine and fragile. 



PLEURONEA FIBROSA, new species. 



Plate 107, figs. 2-9. 



Description. The zoarium is free, idmoneiform, bifurcated, with oval cross 

 section. The fascicles are salient, uniserial, crowded and formed of five tubes at 

 the maximum. The tubes have a visible peristomie; the peristome is round or 

 rectangular. The basal lamella bears a thick layer of tergopores, the orifices of 

 which are irregular but arranged longitudinally and give a fibrous aspect to the 

 zoarium. The ovicell is globular, salient, porous. 



|Peristome-_ _ 0.10 mm. 



FIG. 251. Plcuronea, new genus. 

 Views of Pleuronea (Idmonea) fenestrata Busk, 

 1859, from the Crag of England, showing the zoarium 

 natural size, the frontal side enlarged, cross section of a 

 branch and the frontal and dorsal sides much enlarged. 

 (After Busk, 1859.) 



M< IIHKI'I'IIU'llt*. 



I Distance between the fascicles- _ _ 0.20 



mm. 



