NORTH AMERICAN EARLY TERTIARY BRYOZOA. 135 



so vigorous that very frequently a zooecium, in every respect larger than the. others, 

 reproduces three undeformed primoserial zooecia. We have observed no regen- 

 erated zooecia. 



This species differs from Membraniporidra lalicella in its larger micrometric 

 dimensions and in the absence of a gymnocyst. 



Occurrence. Middle Jacksonian : Wilmington, North Carolina (common) ; 

 Rich Hill, 5 miles southeast of Knoxville. Georgia (rare). 



Cotypes.Czt. Nos. 63900, 63901, U.S.N.M. 



MEMBRANIPORIDRA LATICELLA, new species. 



Plate 26, figs. 3-5. 



Zoarium incrusting other bryozoa. The zooecia are distinct, ogival, broad, with 

 a small convex gymnocyst ; the mural rim is salient, thin, curved, smooth, or slightly 

 granular. The opesium is entire, oval, the narrow end at the front. The ovicell 

 is large, globular, salient, smooth, distinct from the mural rim; it is deeply em- 

 bedded in the distal zooecium. 



. Ao=0.40-0.50 mm. . [7.3=0.60-0.80 mm 



Measurements. Opesia , Zooecia L 



lo= 0.20-0.30 mm. (Zs=0.40-0.50 mm. 



Variation*. The mural rim is not always round. It sometimes has a small 

 sharp termen dividing it into two parts. The gymnocyst is very irregular in form, 

 but it is a constant feature. The regenerated zooecia with double mural rims are 

 frequent. Figure 4 (sri) represents a special case where a regenerated zooecium re- 

 places a normal zooecium but reversed in direction. Figure 5 (zro) illustrates an 

 inverted ovicelled zooecium succeeding a normal zooecium. 



This species differs from Membraniporidra trigemma in its smaller zooecial 

 dimensions and in the presence of a gymnocyst. 



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

 mon) ; Eutaw Springs, South Carolina (rare). 



Cotypes.Csit. No. 63904, U.S.N.M. 



MEMBRANIPORIDRA PORRECTA Canu and Bassler, 1917. 



Plate 26, figs. 6-13. 



1917. Hemlii-aniporidra porrecia CANU and BASSLER, Synopsis of American Early Tertiary 

 Cheilostorae Bryozoa, Bulletin 96, United States National Museum, p. 21. pi. 2, fig. 5. 



The zoarium is free, follicular, formed of two very thin leaves growing back to 

 back and easily separable. The zooecia are large, elongate, distinct, oval, with a 

 proximal, convex gymnocyst; the mural rim is very thin, salient, curved. The 

 opesium is large, elliptical, entire. The ovicell is globular, little elevated, orna- 

 mented with a frontal callosity; it is deeply embedded. A distal septula and two 

 lateral septulae and two distal impressions are present. 



(#0=0.75 mm. . fZz=0.95 mm. 



