NORTH AMERICAN EARLY TERTIARY BRYOZOA. 673 



Forma DIASTOPORA Lamouroux, 1821. 



1821. Diastopora LAMOUROUX, Exposition M(?thorlique des PolMiiers, p. 42. 



The zoarium is unilaminar. 



Historical. Gregory, 1899 (p. 127), included" in the genus Diastopora all the 

 free forms, uni- or bi-laminar, branched or bush}'. Even thus understood, this is 

 not a natural genus, because the ovicell is of a quite varied form and nature. 

 Under these conditions we believe it necessary to recognize the zoarial forms in the 

 exact sense of their authors. The discovery of their ovicells will later permit the 

 classification of the species. According to D'Orbigny, Diastopora is unilamellar, 

 Bidiastopora is bilamellar and branched, and Mesenteripora is lobate. bushy, and 

 meandriform. 



DIASTOPORA TUBAEDES, new species. 

 Plate 106, figs. 4, 5. 



Description. The zoarium incrusts small branched algae ; it is cylindrical, tubu- 

 lar, branched; the zone of growth is very small. The tubes are cylindrical, ar- 

 ranged in regular quincunx, straight, and never bent upward. The peristome is 

 thin, orbicular, oblique; the peristomie is salient, rectilinear. 



Diameter of the peristome 0.14 mm. 



Measurements. 



Distance between the peristomes 0.40-0.50 mm. 



Separation of the peristomes 0.52 mm. 



Length of the peristomie 0.16 mm. 



Occurrence. Midwayan (Clayton limestone) : Luverne, Crenshaw County, 

 Alabama (very rare). 



Holotype. Cat, No. 65421, U.S.N.M. 



DIASTOPORA TUBIFORMIS, new species. 



Plate 121, fig. 8. 



Description. The zoarium incrusts the delicate branched radicells of algae; 

 it is hollow, cylindrical, branched; the zone of growth is rather wide. The tubes 

 are distinct, cylindrical, somewhat bent upward, striated transversally. The peris- 

 tome is elliptical, thin, a little salient, often closed by an entire smooth lamella. 

 There is no peristomie. 



Diameter of the peristomes 0.12 (0.12-0.16) mm. 



Measurements. 



Distance between the peristomes 0.44-0.60 mm. 



Separation of the peristomes 0.50 mm. 



Occurrence. Middle Jacksonian: Near Lenucls Ferry, South Carolina (rare). 

 Holotype. Cat. No. 65299, U.S.N.M. 



55899 20 Bull. 106- 43 



