248 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
two to every two zooecia. The inner side is chitinous or very little calcified and 
bears small tuberosities. 
M easurements : 
Opesium mm. 
of small zooecia jZc>= 0.17 mm. 
[Lz— 0.35 mm. 
Small zooecia 
Zs=0.34r-0.40 mm. 
Opesium 
of large zooecia 
Large zooecia 
j7u?=0.30mm. 
{Zo=0.26 mm. 
fZs=0.40mm. 
lZs=0.50 mm. 
Variations. — The zoarial organization of this species is analogous to that of 
Lunulites distans Lonsdale, 1845, with this difference, however, that the zooecia are 
quite calcified on their basal side (fig. 4). The concave molds (figs. 2. 4) show 
this remarkable character very well. The convex casts which have lost the frontal 
wall of the zooecia (fig. 1) show the internal side of the inner face of the zoarium; 
the rows between the partitions are ornamented with numerous tuberosities, in 
which character the species does not differ from Z. distans Lonsdale. 
Another characteristic of this species is its zooecial dimorphism, which is 
unique in this genus. We are ignorant of the function of the large zooecium. 
Vibracula are not placed in all of the interzooecial angles, as in most of the 
species of lunularia / there is only one for two zooecia in this way — namely, that the 
circular rows with vibracula alternate with circular rows without vibracula. Gabb 
and Horn have proposed the genus Oligotresium for this special character. We 
can not believe that the simple elongation of the small distal canal in which the 
vibraculum may be lodged is a sufficient generic character. 
Lunularia viclcsburgensis Conrad 1847, presents the same arrangement of the 
vibracula, but L. contigua differs in its zooecial dimorphism. 
Occurt'ence. — Middle Jacksonian (Castle Hayne limestone) : Wilmington, North 
Carolina (rare). 
Plesiotypes. — Cat. No. 63999, U.S.N.M. 
LUNULARIA (OLIGOTRESIUM) CLAIBORNICA, new species. 
Plate 13, figs. 13-15. 
Description. — The zoarium is a convex, expanded Lunulites, formed of radial 
rows of zooecia and vibracula. The zooecia are ogival, transverse, distinct: the 
mural rim is very thick; the cryptocyst is small, finely granular. The opesium 
is semilunar and surrounded by a small collar; the proximal border is a little con- 
cave or convex. The ovicell is a distal convexity often covered by the external 
calcification. The vibracula are elongated, elliptical, disposed in radial rows in 
the interzooecial angle for two zooecia; joined between them by a small canal; its 
opesium is narrowed in the lower part by a calcareous lamella, which ends in two 
condyles. On the inner side the radial rows are convex and pierced by large closely 
arranged pores. 
. IAo= 0.17 mm. ^ . ( Zs=0.30 mm. 
-Opesium 1?o=016mm 
T7 ... . fZt)=0.30mm. 
V ibraculum , ... 
Zt’=0.18mm. 
M easurements. - 
Zooecium , ... 
i [;|Zs=0.40mm. 
