NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
179 
avicularium hides the apertura. The apertura is semilunar. The ovicell is globular, 
transverse, smooth; it is widely open in front of the umbo and never closed by the 
operculum. 
Measurements .—Zooecia 
Lz — 0.50-0.60 mm. 
lz =0.25-0.40 mm. 
A ffinities .—The interareolar costules are easily attenuated by fossilization and 
are visible only on the good specimens. The ancestrular zooecia are smaller and 
raised. 
In its exterior aspect this species is close to Cellepora pumicosa Linnaeus, 1768; 
it differs from it in the presence of the interareolar costules and in a different form 
of the apertura. 
Occurrence. —Pleistocene: Santa Barbara (rare) and Santa Monica (Temochal 
Canyon), California (very rare). 
Cotypes. —Cat. No. 68707, U.S.N.M. 
HOLOPORELLA TURRITA Smltt, 1873. 
Plate 46, fig. 1. 
1873. Lepralia turrita Smitt, Floridan Bryozoa, pt. 2, Kongl. Svenska Vetenskaps-Akademiens 
Handlingar, vol. 11, no. 4, p. 65. 
1914. Holoporella turrita Osburn, The Bryozoa of the Tortugas Islands, Florida, Publication 
Carnegie Institution of Washington, no. 182, p. 217 (bibliography). 
Our specimen incrusts a coral. The apertura bears two small cardelles, placed 
in the lower third. - , 
Occurrence. —Pleistocene: Mount Hope, Panama Canal Zone (very rare). 
Habitat .—Waters off Florida (14-71 meters). 
Plesiotype. —Cat. No. 68708, U.S.N.M. 
HOLOPORELLA AVICULIFERA, new species. 
Plate 46, fig. 2. 
Description .—The zoarium incrusts corals, forming very thick masses. The 
zooecia are somewhat erect, convex, and formed of a tremocyst with scattered, 
spaced pores; the frontal bears some interareolar costules. The apertura is formed 
of a large anter and of a concave poster and arranged at the base of a short peristomie. 
There is a small avicularium in the peristomie. On the frontal some areolar pores 
are transformed into small orbicular avicularia. 
,, , . . (k=0.18 mm. 
Measurements .—Apertura , . 
r [ia = 0.20mm. 
Affinities .—This species presents somewhat the aspect of Discopora pertusa 
Smitt, 1872. It differs from it in the presence of the small disseminated avicularia 
and in the absence of oral mucro. 
Occurrence. —Pleistocene: Mount Hope, Panama Canal Zone (rare). 
Holotype.— Cat. No. 68709, U.S.N.M. 
HOLOPORELLA MUCRONATA, new species. 
Plate 46, fig. 7. 
Description .—The zoarium incrusts sponges. The zooecia are little erect, sur¬ 
rounded by a line of large, spaced, areolar pores; the little salient, areolar costules 
meet at an enormous, wide, oral, very salient mucro. Two very small cardelles 
separate the anter from the concave poster. Some areolar pores are transformed 
into small orbicular or triangular avicularia. 
