768 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
calcified (fig. 12) ; they are generally empty and appear white in tangential (fig. 11) 
and longitudinal sections (fig. 15). The interstices disappear when the section 
passes rigorously through the point of tangency (fig. 15). 
The function of the tergopores is evidently zoarial, but we are totally ignorant 
of their nature. 
Affinities. — This species much resembles Iclmonea pert/usa Reuss, 1847, in its 
basal lamella, and in the fossils, it is difficult to separate them. It differs from it 
in its frontal, the fascicles of which are close together and not spread out from 
the median line. 
It differs from Iclmonea reticulata Reuss, 1869, in the very different nature of 
its tergopores, and from Pleuronea fusiformis in the exterior polygonal form of 
its tergopores and in their larger diameter. 
Occumence. — Claibornian (Gosport sand) : One mile southwest of Rockville, 
Clarke County, Alabama (rare). 
Lower Jacksonian (Moodys marl): Jackson, Mississippi (common). 
Middle Jacksonian: Rich Hill 5f miles southeast of Knoxville, Crawford 
County, Georgia (very rare). 
Upper Jacksonian (Ocala limestone) : Old Factory, about 11 miles above 
Bainbridge, Georgia (very rare). 
Vicksburgian (Red Bluff clay) : One-quarter mile west of Woodwards, Wayne 
County, Mississippi (rare). 
Vicksburgian (Marianna limestone) : Vicksburg, Mississippi (lower bed, 
rare). 
Cotypes. — Cat. No. 65432, U.S.N.M. 
PLEURONEA FUSIFORMIS, new species. 
Plate 161, figs. 3, 4. 
Description. — The zoarium is free, bifurcated, idmoneiform. The bundles are 
salient, .transverse, alternate on each side of the median axis, and formed of four 
to five zooecia. The tubes are little visible; the orifice is rectangular and the 
peristome is thin. The basal lamella is convex and bears fusiform tergopores. 
The ovicell is large, globular, salient; the oeciostome is adjacent to a bundle and 
subterminal. 
Distance between the fascicles 0.36 mm. 
Width of the fascicles 0.10 mm. 
Measurements.— Zoarial widt h 0.50-0.60 mm. 
Dimensions of the tergopores 0.0T-0.08 mm. 
Affinities. — This species is the American representative of Idmonea reticulata 
Reuss, 1869, of the Priabonian of the Vicentin. It differs from it, however, in the 
more elongated form of the tergopores. 
Occurence. — Vicksburgian (Marianna limestone) : Salt Mountain, 5 miles 
south of Jackson, Alabama ( very rare). 
Holotype. — Cat. No. 65442, U.S.N.M. 
