NORTH AMERICAN EARLY TERTIARY BRYOZOA. 133 



Examples of total regeneration are very rare. 



Affinities. The termen of the mural rim sometimes becomes very sharp. and 

 crenulated (fig. 10). 



This species is quite similar to <rr<nnm< :11<i crassimarc/inata, differing only in its 

 small dimensions. It is not a variety because it occurs at different localities. 



Occurrence. Middle Jacksonian : IS miles west of Wrightsville, Johnson 

 County, Georgia (very rare). 



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

 County, Alabama (rare) ; Chipola River, east of Marianna, Jackson County, 

 Florida (rare) ; 11 miles above Bainbriclge, Georgia (rare). 



Vicksburgiaii (" Chimney rock '' of Marianna limestone) : One mile north of 

 Monroeville. Alabama (rare). 



Cotypes.Csat. Xos. 63898. 63S99. U.S.X.M. 



Genus MEMBRANIPORIDRA Canu and Bassler, 1917. 



1917. Hembraniporidra CANU ami BASSI.EK. Synopsis of American Early Tertiary Cheilostoine 

 Bryozoa, Bulletin 96, United States National Museum, p. 21. 



The operculum always closes the ovicell. Xo dietellae. No avicularia. One 

 large distal septula ; two pairs of lateral septulae. 



Genotype. Metnbramporidra porrecta Canu and Bassler, 1917. 



Range. Jacksonian and Vicksburgian. 



The ovicell is deeply excavated in the distal zooecium. It is only by dissection 

 that we are able to prove by the continuity of the mural rim, although very thin 

 distaljy, that the ovicell is indeed hyperstomial. The mural rim is always enlarged 

 at the base and finely granular. 



This genus differs from Alderina Xorman, 1903, not only in the closure of the 

 ovicell by the opercular valve, but also in the absence of dietellae. 



It is probable that many recent species may be included in this genus. The 

 most common form among them might well serve as the true genotype. 



MEMBRANIPORIDRA OECIOPOROSA. new species. 



Plate 26, figs. 1, 2 



Descriptwn. The zoarium incrusts shells. The zooecia are elongated, distinct, 

 elliptical-; the mural rim is slightly salient, curved, enlarged at the base, where it 

 has two lateral furrows, ornamented with very small granulations radially ar- 

 ranged. The opesium is elliptical. The ovicell is large, globular, salient, orna- 

 mented with a frontal callosity, the wall of which, lying on the distal part of the 

 zooecium, is finely porous. 



. (7w=0.22-0.25 mm. . |Z.2=0.35 mm. 

 Measurements. Opesia , .. Zooecia, 



(?<?=0.1o-0.1< mm. 173=0.23-0.2. > mm. 



Variations. This species is very irregular is its gemmation, and deformed 

 zooecia are numerous. The ovicell is interesting for its peculiarities a fragile, 

 frontal callosity and finely porous floor. The callosity is finely granular like the 



