202 
BULLETIN 125, UNITED STATES NATIONAL MUSEUM. 
Affinities. —This species differs from Mesenteripora meandrina Robertson, 1910, 
in the ovicell not placed near the zoarial margin, and in its tubes grouped in fascicles. 
In spite of exterior appearances the tubes are not arranged as in Reticulipora, 
the axis of the apertura being placed in the longitudinal axis of the zooecia. 
Occurrence. —Pleistocene: Santa Barbara (common), and Santa Monica 
(Rustic Canyon), California (rare). 
Cotypes. —Cat. Nos. 68747, 68748, U.S.N.M. 
Genus D1APEROECIA Canu, 1918. 
(For description, see Bulletin 106, U. S. National Museum, p. 740.) 
DIAPEROECIA FLABELLATA, new species. 
Plate 43, figs. 18, 19. 
Description. —The zoarium is free, bilamellar and formed of flabellate fronds, 
and irregularly twisted. The tubes are little visible, widened at their extremity; 
the peristome is thin, salient, elliptical, horizontal. The ovicell is convex, smooth, 
traversed by 6-10 tubes; the oeciostome is crescentric. and joined to an ordinary 
peristome. 
Measurements .— 
Diameter of the peristome_ 0. 15 mm. 
Distance between the peristomes___ 0. 42-0. 50 mm. 
Separation of the peristomes.. 0. 50-0. 55 mm. 
Occurrence. —Pleistocene: Santa Monica (Tremochal Canyon) (rare), and 
Dead Mans Island, off San Pedro, California (very rare). 
Holotype. —Cat. No. 68749, U.S.N.M. 
DIAPEROECIA MILNEANA D’Orbigny, 1839. 
Plate 6, figs. 20, 21. 
1839. Idmonea milneana D’Orbigny, Voyage dans L’Am4rique M&ridionale, vol. 5, pt. 4, p. 20, 
pi. 9, figs. 17-21. 
1919. Idmonea milneana Canu and Bassler, Geology and Paleontology of the West Indies, Bryozoa, 
Publications of the Carnegie Institution of Washington, No. 291, p. 99, pi. 6, figs. 20, 21. 
1920. Idmonea milneana Canu and Bassler, North American Early Tertiary Bryozoa, Bulletin 
106, U. S. National Museum, p. 773, pi. 136, figs. 1-12. 
This recent species has been identified in a number of Tertiary formations 
of Europe and in the Jacksonian and Vicksburgian of North America. So far 
the only discovery of it in th^ post-Oligocene strata of North America is in the 
Lower Miocene of Santo Domingo, where the single specimen here illustrated has 
been found. 
The discovery of numerous ovicelled specimens of this species in dredgings 
from the Gulf of Mexico cause us to refer it generically as above. 
Occurrence. —Lower Miocene (Bowden horizon): Cercado de Mao, Santo Do¬ 
mingo (rare). 
Plesiotype. —Cat. No. 68750, U.S.N.M. 
I 
