NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
289 
The gymnocyst which surrounds the cribriform area is very inconstant and is 
developed chiefly in the lower part of the zooecia. 
This species ditfers from M embraniporella, subagassizi in its zoarial dimensions, 
its much smaller micrometric measurements, and its numerous frontal lacunae. 
Occurrence. — Middle Jacksonian: Eighteen miles west of Wrightsville, John- 
son County, Georgia (rare) ; one-half mile west of Georgia Kaolin Company’s Mine, 
Twiggs County, Georgia (rare). 
Cotypes — Cat. Nos. 64017, 64018, TJ.S.N.M. 
MEMBRANIPORELLA MONILIFERA, new species. 
Plate 41, figs. 9, 10. 
Description. — The zoarium incrusts shells. The zooecia are distinct, separated 
by a furrow, elongated, elliptical, wide; the frontal is convex; the costules are 
radially arranged, united near the zoarial axis, separated by long, rather wide slits, 
•and ornamented with two tuberosities of which one is a talon. The aperture is 
semi-elliptical and is limited by a thin peristome which bears at least two. large, 
hollow spines and, in front, by a calcareous thickening in the form of a T. The 
ovicell is closed by the operculum. There is a vestibular arch and four spines, 
of which the first pair is the larger. 
M easurements. — Apert ure 
( ha= 0.07 mm. 
[la— 0.07 mm. 
„ . [7,0=0.50 mm. 
Zooecia'', 7 rv A in 
lfe=0.3o-0.40 mm. 
Variations. — This species is characterized by its two costular tuberosities; 
one is at the aperture itself and the other is close to the zooecial axis. The general 
effect of these tuberosities is that of a double necklace around the zooecia. 
The part formed by the union of the costules forms in front of the zooecia a 
sort of shield of variable size. 
Very often the costular tuberosities do not exist; the zooecia then have the 
aspect of a very simple M embraniporella. 
There are no lumen pores. 
Affinities. — This species differs from M embraniporella bioculata in its smaller 
micrometric dimensions, the absence of oral avicularia, and the presence of tuberosi- 
ties on the costules. In its incrusting zoarium it differs from all the other species 
of M embraniporella studied. 
Occurrence. — Middle Jacksonian: near Leunds Ferry, South Carolina (rare) ; 
Eutaw Springs, South Carolina (rare). 
Cotypes.- — Cat. Nos. 64019, 64020, TJ.S.N.M. 
MEMBRANIPORELLA (?). SUBAGASSIZI, new species. 
Plate 84, figs. 8-13. 
Description. — The zoarium is free, cylindrical, formed of five or six longitudinal 
rows of zooecia. The zooecia are large, distinct, separated by a furrow, elliptical; 
the frontal is very convex and formed by a cribriform area surrounded by a 
smooth gymnocyst; the cribriform area contains 10 to 12 transversal and radial 
costules. Each costule is separated from its neighbor by a large lacuna followed 
55899— 19— Bull. 106 19 
