NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
37 
Genus OGIVALINA Canu and Bassler, 1917. 
(For description see Bulletin 106, U. S. National Museum, p. 117.) 
OGIVALINA MUTABILIS Canu and Bassler, 1919. 
Plate 1, fig. 3. 
1919. Ogivalina mutdbilis Canu and Bassler, Geology and Paleontology of the West Indies, Bry- 
ozoa, Publication Carnegie Institution of Washington, No. 291, p. 80, pi. 1, fig. 4. 
Description .—The zoarium is incrusting. The zooecia are elongated, oval, 
distinct, separated by a deep furrow; the mural rim is thin, smooth, rounded; there 
is often a small gvmnocyst. The opesium is very large, irregular, more often oval. 
The ovicell is endozooecial, small, little convex. Sometimes there is a small inter- 
zooecial fusiform avicularium (?) 
Measurements .—Opesia 
Zooecia 
Lz = 0. 75-0.95 mm. 
lz — 0. 50-0.70 mm. 
J/io = 0. 60-0 70 mm. 
I lo = 0. 30-045 mm. 
The great irregularity of form and zooecial dimensions of this species occasions 
its name. There are some variations which recall those of Membranipora irregularis 
Manzoni, 1875, 5 which possesses a mural rim enlarged at the base and also some large 
interzooecial avicularia. 
The present species differs from the splendid Ogivalina eximipora Canu and Bas¬ 
sler, 1917, from the Middle Jacksonian in its smaller dimensions, in the absence of 
cryptocyst and in the presence of a gymnocyst. The avicularium (?) is identical in 
form and position. 
Occurrence. -Upper Oligocene (Emperador limestone): Old quarry, one-third 
mile north of west of Empire, Panama Canal zone (rare). Upper Oligocene (Anguilla 
formation): Soutlvwest side Crocus Bay Hill, Anguilla, Leward Islands (rare). 
Holotype. —Cat. No. 68443, U.S.N.M. 
OGIVALINA PARVULA Ulrich and Bassler, 1904. 
Plate 12, fig. 6. 
1904. Membranipora parvula Ulrich and Bassler, Bryozoa, Maryland Geological Survey, Mio¬ 
cene, p. 310, pi. Ill, fig. 1, 2. 
The original description of this species is as follows: 
In its general zoarial and zooecial characters this species resembles Membranipora germana Ulrich 
and Bassler, 1904 and M. plebeia Gabb and Horn, but it is readily distinguished by the smaller size and 
less elongate form of its zooecia. The walls are also relatively thicker while the longitudinal arrangement 
of the zooecia is more pronounced. Measuring longitudinally, 8 zooecia occur in 3 mm. and transversely 
12 may be counted in the same space. 
To the above we would add that there is a small gymnocyst and that the ovicell 
is endozooecial and the avicularium is interzooecial. 
Occurrence —Miocene (Calvert formation): Reed’s Maryland (rare.) 
Holotype.— Cat, No. 68444, U.S.N.M. 
s Briozoi del pliocene antico di Castrocaro Bologna, 1875, p. 10, pi. 1, figs. 5, 8. 
