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NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 155 
rior) is transverse, subelliptical; the peristomice bears a rimule spiramen'arranged 
between two salient lips. The ovicell is large, convex, smooth, buried in the distal 
zooecium; its orifice is very large and located in front of the two lips. Many zooecia 
bear a very large avicularium arranged obliquely on the frontal and provided with 
a curved, very salient beak. The zooecia without avicularia bear some small 
scattered pores. 
Measurements. —Peristomice: lpe = 0.10 mm. 
„ . \Lz = 0.46-0.60 mm. „ , fZ/=2.00mm. 
t Iz = 0.20—0.30 mm. [ lf= 0.3D-0.75 mm. 
Affinities. —This species differs from Phidolopora pacifica Robertson, 1908, in 
the smaller dimensions of its peristomice, which measure more than 0.10 mm. The 
general aspect is therefore that of bearing apertures much more scattered and in 
having a peristomice much smaller than the zooecial width. 
The micrometric variations are extraordinary. On the same zoarium one may 
find zooecia 0.50 mm. by 0.20 mm. with zooecia 0.46 by 0.26-0.30 mm. Frequently 
the peristomice of the ovicelled zooecia is somewhat wider than that of the other 
zooecia. The vibices are also very irregular; thav are salient, but disappear easily 
in fossilization. 
Occurrence— Pleistocene: Dead Mans Island off San Pedro (rare), Santa Monica 
(common), and Santa Barbara, California (very common). 
Plesiotypes. —Cat. No. 68663, U.S.N.M. 
Genus RHYNCHOZOON Hincks, 1891. 
(For description, see Bulletin 106, U. S. National Museum, p. 506.) 
RHYNCHOZOON VAUGHANI Canu and Bassler, 1919. 
) 
Plate 2, fig. 22; plate 4, figs. 1, 2. 
1919. Rhynchozoon vaughani Canu and Bassler, Geology and Paleontology of the West Indies, 
Bryozoa, Publications of the Carnegie Institution of Washington, no. 291, p. 94, pi. 2, fig. 
23; pi. 4, figs. 1, 2. 
Description. —The zoarium is unilamellar. The zooecia are large, distinct, 
hexagonal or claviform; the frontal is smooth, convex, surrounded by a line of 
small scattered areolar pores. The apertura is large, suborbicular, with a wide 
proximal rimule; the peristomie is deep and widened; the very irregular peristome 
bears some large tubercles; the false rimule is compressed between two large 
tuberosities, one of which bears an oral avicularium transversely arranged. 
Measurements. —Apertura 
ha = ? 
la = 0.20 mm. 
Zooecia 
Lz = 0.60 mm. 
I lz = 0.50 mm. 
Affinities. —This species differs from Rhynchozoon solidum Osburn, 1914, which 
it much resembles, in its much larger micrometric measurements and in the absence 
of the small frontal avicularium. 
Occurrence. —Lower Miocene (Bowden horizon): Cercado de Mao, Santo Do¬ 
mingo (very rare). 
Cotypes. —Cat. No. 68664, U.S.N.M. 
