NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
391 
HIPPOMENELLA TUBEROSA, new species. 
Plate 51, figs. 4, 5. 
Description . — The zoarium incrusts bryozoa. The zooecia are large, elongated, 
elliptical, or hexagonal, separated by a deep furrow ; the frontal is very convex, 
surrounded by a double row of areolae and decorated with tuberosities grouped in 
lines radiating from the mucro. The aperture is semielliptical in the interior 
with two cardelles placed very low ; on the exterior it is surrounded distally by a 
peristome garnished with six large spines and proximally by a salient mucro. 
The ovicell is large, elongated, salient, hyperstomial, little imbedded in the distal 
zooecia, never closed by the operculum; the two areas are garnished laterally with 
an arched slit. The two avicularia are of equal dimensions; they are small, little 
salient, triangular, provided with a pivot, placed at some distance below the aper- 
ture; their beak is pointed downward and toward a neighboring aperture. 
Measurements . — Aperture 
| Aa=0.14— 0.16 mm. 
[7«=0.14 min. 
Zooecia 
7,2=0.84: mm. 
7,2=0.70 mm. 
Affinities . — This is a splendid species. The frontal tuberosities are of pleuro- 
cystal origin and the olocyst is easily visible below. 
The species differs from Hippomenella ligulata. which shows some radial 
granulations, in its larger micrometric dimensions (Lz= 0.84 and not 0.70 mm.) 
and in its much less salient avicularia. 
O commence . — Middle Jacksonian (Castle Hayne limestone) : Wilmington, 
North Carolina (very rare). 
Iiolotype. — Cat. No. 64087, U.S.N.M. 
HIPPOMENELLA AXICULATA, new species. 
Plate 51, figs. 10-13. 
Description.— The zoarium incrusts bryozoa. The zooecia are distinct, wide, 
irregular in position; the frontal is little convex, smooth, surrounded by three lines 
of small and triangular areolae. The aperture is semielliptical with two cardelles, 
placed quite low; the peristome supports six to eight distal spines; an enormous, 
salient mucro, oblique or erect, lobate, hides the aperture more or less. The ovicell 
is large, salient, imbedded in the distal zooecium, is hyperstomial and is never closed 
bv the operculum; it frontal area is perforated with an arched slit. The avicularia 
placed near the aperture are small and irregular. 
Measurements . — Aperture 
r ha— 0.16 mm. 
[7a=0.14 mm. 
Zooecia 
72=0.68-0.70 mm. 
72=0.50 mm. 
Variations . — The mucro forms in front of the aperture a small pallet , quite 
variable in form and dimensions. We are ignorant of the physiologic use of this 
organ, but it appears essential and analogous to that of the spines. If it be true 
that their existence is for the purpose of capturing the diatoms, our species must 
have been excessively voracious. What is strange is the absolute irregularity of the 
mucro ; no one of them has any resemblance to the other and they are of all dimen- 
sions. 
