NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



109 



of the ribs presents no sign of calcification. It is probable, however, that the ecto- 

 cyst is not the only external membrane and that a chitinous cryptocyst replaced the 

 calcified deposit which is wanting here. The zooecia appear thus to be both poly- 

 pidian and hydrostatic. 



On the inner side of the x.cnrium a fine white mealy powder refills the ribs, but 

 this species is easily distinguished from Otionella tuberosa and from 0. perforata 

 by its gigantic vibracula and by the entire absence of the opesial collar. 



Occurrence. Middle Jacksonian: 3J: miles south of Perry, Georgia (common) ; 

 Balclock. Barnwell County, South Carolina (common). 



Jacksonian (Zeuglodon zone) : South side of Suck Creek, Clarke County, 

 Mississippi (rare) ; Shubuta. Mississippi (rare). 



Cotypes.Cat. No. 63876. U.S.N.M. 



C. Ogivalma g Hincksina A . Vibracellina D M e ' nhrendoecium E. Setosellina 



FIG. 27. Genera of Membraniporae with endozooecial ovicell. 



A. Vibracellina capillaria Canu and Bassler, 1917, X 20. Claibornian, Caldwell County, 

 Texas. 



B. Hincksina megavicularia Canu and Bassler ,1917, X 20. Middle Jacksonian, Wilmington, 

 North Carolina. 



C. Ogivalina eximipora Canu and Bassler, 1917, X 20. Middle Jacksonian, Rich Hill, 

 Crawford County, Georgia. 



D. Membrendoecium rectum, new species, Vicksburgian, By ram, Mississippi. 



E. Setosellina roulei Calvet, 1907, X 25. Recent. 



SECTION II. MEMBRANIPORAE WITH ENDOZOOECIAL OVICELL. 



We have recognized four genera of Membranipores provided with an 

 endozooecial ovicell, a structure which distinguishes them from genera of the first 

 section quite as clearly as from those which have a hyperstomial ovicell. Fur- 

 thermore, these four genera do not appear to belong even to the same family. 



Hincksina according to Norman is a member of the Flustridae. 



Vibracellina may perhaps belong to the Lunulariidae. 



Ogivalina may be referred to the Onychocellidae. 



M embrendoecium may perhaps belong to the Farciminariidae. 



