NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 199 
IDMONEA PLANULA, new species. 
Plate 26, figs. 13-15. 
Description. —-The zoarium is free, wide, with semielliptical section; the dorsal 
is flat and striated transversally. The fascicles are salient, opposite, quite close 
but diverging from the median crest. The tubes are visible, separated by a little 
salient thread, and number three or four to a fascicle; the peristomes are thin 
and rectangular. 
Measurements. —Width of fascicles..0.20 mm. 
Distance between the fascicles. .. 0.40-0.60 mm. 
Diameter (on the zoarium) of the first tube_0.24 mm. 
Number of the tubes... 3-4. 
Width of the zoarium...... 1.20 mm. 
Affinities. —This species has the general aspect of Idmonea petri D’Archiac, 
1846. It differs from it in a greater distance between the fascicles (more then 
0.40 mm.) and in the larger zoarial dimensions. 
Occurrence. —Miocene (Choctawhatchee marl): Jacksons Bluff, Ocklocknee 
River, 25 miles southwest of Tallahassee, Florida (very rare). 
Holotype. —Cat. No. 68741, U.S.N.M. 
IDMONEA CALIFOKNICA D’Orbigny, 1852. 
Plate 43, figs. 1-9. 
1852. Idmonea califomica D’Okbigny, Paleontologie francaise, Terrains cr4taces, vol. 5, Bryozo- 
aires, p. 732. 
1855. Idmonea califomica Conrad, Notes on Miocene and Post-Pliocene deposits of California, 
Proceedings Academy Natural Sciences Philadelphia, vol. 7, p. 441. 
1862. Idmonea califomica Gabb and Horn, Monograph Polyzoa, Secondary and Tertiary formations 
North America, Journal Academy Natural Sciences Philadelphia, ser. 2, vol. 5, p. 168, 
pi. 21, fig. 56. 
1910. Idmonea califomica Robertson, Cyclostomatous Bryozoa of the west coast of North America, 
University of California Publications, Zoology, vol. 6, p. 253, pi. 23, figs. 39—41 (bibli¬ 
ography). 
Measurements. —Diameter of the orifice..0.20 mm. 
Diameter of the peristome... 0.28 mm. 
Width of the fascicles.... 0.28 mm. 
Distance between the fascicles..— 0.80 mm. 
Variations. —This giant species seems to be restricted to the American shores 
of the Pacific. 
The fascicles are almost opposite. On the median axis there is a longitudinal 
row of isolated tubes, often closed by a calcareous diaphragm. 
In tangential section the walls are perforated, but the perforations are no 
larger than in other species of Idmonea with small dimensions. In longitudinal 
section the zooecial walls appear very thick. In transverse section the tubes 
are rectangular. The ovicell is large, convex, placed on the median crest and 
finely porous. It surrounds the isolated zooecia of the median axis, which gives 
it the aspect of Diaperoecia, but it does not surround the fascicles and its inter¬ 
fascicular lobes are very short. 
Occurrence. —Pleistocene: Santa Monica (rare), Dead Man’s Island, off San 
Pedro (very common), and Santa Barbara, California (very common). 
Plesiotypes. —Cat. Nos. 68742, 68743, U.S.N.M. 
