130 
BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
is salient tuberous, or garnished with six spines; two very small cardelles placed 
on the lower third separate the anter from tne concave poster. The ovicell is 
globular, salient; it can not be closed by the operculum. 
Measurements. —Apertura j Zooecia 
r l la = 0.05 mm. 
Affinities. —The saliency of its peristome and its small 
this species quite well. 
Occurrence. —Pleistocene: Mount Hope, Panama Canal 
Holotype. —Cat. No. 68604, TJ.S.N.M. 
f Lz = 0.40 mm. 
[ [lz = 0.25 mm. 
dimensions characterize 
Zone (very rare). 
HIPPOPORINA G1BBOSA, new species. 
Plate 18, fig. 10. 
Descriptions. —The zoarium incrusts shells. The zooecia are distinct, separated 
by a furrow of little depth, hexagonal, elongate; the frontal is smooth, little convex, 
garnished with a frontal gibbosity. The apertura is elongate and formed of a large 
anter separated by two cardelles from a small poster with proximal border almost 
straight. The ovicell is large globular, widely open. 
Measurements. —Apertura 
ha-= 0.14 mm. 
Za = 0.11 mm. 
Zooecia 
1)2 = 0.45-0.50 mm. 
lz = 0.30-0.35 mm. 
Variations. —No other known species of the genus Hippoporina presents a 
frontal gibbosity; it ^therefore easy to distinguish this one and no error is possible. 
The micrometric measurements of the zooecia are quite variable^and our figure 
shows a zooecium measuring 0.60 mm. in width. This irregularity is difficult to 
explain, for it is not occasioned only by calcification; it is real and easy to ascertain 
on the worn zooecia whose frontal is broken. In most of the other Cheilostomatous 
bryozoa the irregularity is more apparent than real and examination of the interiors 
reveals the zooecia to be practically equal. 
Occurrence. —Miocene (Duplin marl): Wilmington, North Carolina (rare). 
Holotype. —Cat. No. 68605, U.S.N.M. 
HIPPOPORINA(?) VESTITA, new species. 
Plate 18, figs. 7-9. 
Description. —The zoarium incrusts oysters. The zooecia are distinct, hexago¬ 
nal, separated by a furrow of little depth, with little convex frontal, smooth and cov¬ 
ered by two or three superposed calcareous pellicles. The apertura is elliptical, 
elongate. The ovicell is little salient; it bears a very fragile frontal area. 
Variation. —This is a strange species, the generic position of which is very un¬ 
certain; but we are unable to create a special genus for such incomplete specimens. 
The latter bear only broken ovicells and we can not obtain an exact idea of their 
nature. The exterior calcification is very remarkable. The deposit of two or 
three calcareous pellicles can only be explained by an endocystal covering, immedi¬ 
ately adjacent to the ectocyst. 
Occurrence. —Miocene (Choctawhatchee marl): Jackson Bluff, Ocklocknee 
River, 25 miles southwest of Tallahassee, Florida (rare). 
Holotype. —Cat. No. 68606, U.S.N.M. 
