304 
BULLETIN 106, UNITED STATES NATIONAL, MUSEUM. 
This species is somewhat like the Cribrilina chelys Koschinsky, 1885. of the 
Priabonian of the \ icentin. The latter, however, is provided with interzooecial 
avicularia. 
We unfortunately possess only the figured specimen. 
Occurrence. — Vicksburgian (Byram marl): Byram, Mississippi (very rare). 
Holotype. — Cat, No. 64261, U.S.N.M. 
GEPHYROTES QUADRISERIALIS, new species. 
Plate 42, figs. 4, 5. 
Description. — The zoarium is free, cylindrical, bifurcated, formed of four longi- 
tudinal rows of zooecia opposed to each other, two by two. The zooecia are dis- 
tinct, elongated, separated by a furrow. The frontal is very convex and formed 
of nine pairs of closely united costules. Each costule bears at least two lumen 
pores; the first pair bifurcates to form the spiramen and the peristomial lamella. 
The aperture is elliptical and transverse and buried at the bottom of the peri- 
stomice. 
( 7,3= 0.65-0.75 mm. 
1 7.2=0.40 mm. 
Measurements. — Zooecia 
Affinities. — The spiramen is not constant and is sometimes replaced by a pseu- 
dorimule cut at the middle of the lower lip of the peristomice. 
As the spiramen is almost vertically placed, it is clearly visible only when the 
specimen is inclined; then, viewing it transversely, the proximal border of the 
aperture beneath it is quite visible. The lacunae are so small that they can not 
be shown in the figure. 
The genus Corbtmpora of MacGillivray also has quadriserial zoaria, but the 
zooecia have no spiramen. 
The structure of the costules is identical with that in Gephyrotes convexa; 
but G. quadnserialis differs in its free and nonincrusting zoarium, in its nonovi- 
eelled zooecia bearing a spiramen, and in the entire absence of a zooecial gymnoevst. 
The species under discussion is the equivalent of Cribrilina crenatimargo- 
haueri Reuss, 1847, of the Priabonian of the Vicentin, but differs from it in its 
quadriserial and not bilamellar zoarium and in the presence of the spiramen. 
Gephyrotes quadriseriaMs furthermore has no oral avicularia and is of such 
an aberrant type that it will be convenient perhaps to separate it genericallv when 
the ovicell has been discovered. 
Occurrence— Upper Jacksonian (Ocala limestone) : Chipola River, east of 
Marianna, Jackson County, Florida (rare). 
Cotypes.- — Cat, No. 64031, U.S.N.M. 
Genus METRACOLPOSA Canu and Bassler, 1917. 
1917. Metracolposa Canu and Basslee, Synopsis of American Early Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 34. 
The costules are separated by numerous lacunae. The aperture is semilunar. 
The operculum in opening closes the ovicell. The ovicell is large and deeply em- 
bedded in the distal zooecia. The ovicelled zooecia have a large aperture. 
