NORTH AMERICAN EARLY TERTIARY BRYOZOA. 263 



(fig. 12) one to ascertain how the polypide may project between the partition and 

 the opesial collar. 



Affinities. The a zooecia are much narrower than in Steganoporella rectan- 

 ffularia (fe=0.24 mm. instead of 0.36 mm.). 



Steganoporella jacksonica differs from Steganoporella incrustans in its bila- 

 mellar zoarium and its perforated cryptocyst. 



It differs from Steganoporella viclcsburgica in its much smaller micrometric 

 dimensions. The widespread occurrence of this species in the Jacksonian has 

 occasioned its specific name. 



Occurrence. Lower Jacksonian: Jackson, Mississippi (rare). 



Middle Jacksonian: Baldock, Barnwell County, South Carolina (very abun- 

 dant) ; 18 miles west of Wrightsville, Georgia (rare) ; 3J miles south of Perry, 

 Georgia (rare) ; 17 miles northeast of Hawkinsville, Georgia (rare) ; 3^ miles west 

 of Grovania. Georgia (rare) ; ^ mile southeast of the Georgia Kaolin Company 

 Mine, Twiggs County, Georgia (rare). 



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

 County, Alabama. 



Cotypes.Cnt. Nos. 64003-64005, U.S.N.M. 



STEGANOPORELLA RECTANGULARIA, new species. 

 Plate 40, fig. 1. 



Description. The zoarium is bilamellar. The a zooecia are short, wide, dis- 

 tinct, ogival, with the distal walls sinuous; the mural rim is thin and salient; the 

 cryptocyst is deep and porous; the polypide tube is somewhat salient and dis- 

 tinct; the two opesiules are rounded, broad, and scarcely visible; the opesium is 

 semilunar and transverse. The R zooecia are much larger; their polypide tube 

 is very salient, and the two opesiules are deep. 



1 7(0=0.12-0.14 mm. fZz=0.44mm. 



Measurements. Opesium {, ^or,,. '' zooecium , 



\Z0=0.22-0.24 mm. I7s=0.36mm. 



n f 3=1.15 mm. 



ti zooecium 7 n __ 



U3=0.55mm. 



Affinities.- Only two specimens have been found, but they appear distinct from 

 Steganoporella jaclcsonica because of their great zooecial width, and by the sinuosi- 

 ties of the distal walls of the mural rim. The species requires further examination. 



Occurrence. Lower Jacksonian (Moodys marl) : Jackson, Mississippi (very 

 rare). 



Holotyps.Czt. No. 64006, U.S.N.M. 



STEGANOPORELLA INCRUSTANS, new species. 



Plate 40, figs. 2-6. 



Description. The zoarium incrusts shells, sometimes forming broad expan- 

 sions. The a zooecia are small, elongated, distinct; their mural rim prominent, 

 thin; the cryptocyst is deep, smooth or finely granulated; the opesium is semi- 



