264 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
lunar, transverse; there is not a complete polypicle tube; the polypidian convexity 
is prominent; the two opesiules are rounded, asymmetrical, rather distinct. The B 
zooecia are of greater size and much enlarged in their distal part; the polypi de 
tube is median, quite prominent, complete ; the opesiules are large, rounded or linear 
nearly alike; the oral arch is single or double and salient; the distal niche is large, 
of slight depth, and smooth. 
M easuremen ts.- 
. ( /? <9=0. 05-0. 10 mm. 
-Opesium 7 . 
r 17<9=0.20 mm. 
[713=0.70-0.80 mm. 
| 7s = 0.34 mm. 
B zooecium 
a zooecium 
[ Lz— 0.50 mm. 
[73=0.30-0.36 mm. 
V aviations.- — The micrometric dimensions are extraordinarily variable. The 
B zooecia attain a length of 1.10 mm. in the specimens from the vicinity of Bain- 
bridge, Georgia ; they alwaj^s engender two new rows of zooecia. 
The partition of the a zooecia is very oblique and begins at one of the upper 
distal angles (fig. 5). It becomes very visible after rubbing away the zoarial sur- 
face. The polypide slips between this partition and the opesiule in order to emerge 
from the polypidian convexity. 
The polypide tube of the B zooecia is median, straight (see fig. 4, m), or 
curved nearly at a right angle. The contortions of the polypide in order to emerge 
from the zooecium (<7), are really considerable (fig. 4) ; we are in ignorance regard- 
ing the use of this complicated structure; the embryos developed at the base of the 
distal chamber are not the cause of it. 
One of the zoaria before us covers 5 square centimeters of surface. 
Affinities. — This species differs from Steg anoporella jacksonica in its incrusting 
zoarium, in its a zooecia, which are shorter, and its nonperforated cryptocyst. 
It is distinguished from Steganoporella (Lepralia) frrna Reuss, 1867. by its B 
zooecia, which are much larger. 
Occurrence. — Upper Jacksonian (Ocala limestone) : Chipola River, east of 
Marianna, Jackson County, Florida (common) ; West bank of Sepulga River, 
Escambia County, Alabama (very rare) ; 4 miles below Bainbridge, Georgia (very 
rare) ; Old Factory, 14 miles above Bainbridge, Georgia (very rare). 
Middle Jacksonian: 17 miles northeast of Hawkinsville, Georgia. 
Cotypes. — Cat. Nos. 64007-64009, U.S.N.M. 
STEGANOPORELLA VICKSBURGICA, new species. 
Plate 84, figs. 1-7. 
Description.- — The zoarium is formed of two lamellae placed back to back and 
easily separable. The a zooecia are large, distinct, elongate, without distal niche; 
the mural rim is thin and salient ; the cryptocvst is deep and perforated with very 
small pores; the opesium semilunar, transverse; the polypide tube is complete but 
very little prominent, and the opesiules are hardly visible. The-7? zooecia are larger 
and have a deep, smooth distal niche; the polypide tube is large and very promi- 
