NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 
193 
This species must not be confounded with Mamillopora cupula Smitt, 1872. 
It differs from it in its ovicell, which is not bilobate, and in its ovarian zooecia 
which are not larger than the others. 
Occurrence. —Lower Miocene (Gatun formation): Banana River, Costa Rica 
(common). Lower Miocene (Bowden horizon): Rio Cana, Rio Gurabo, and Cercado 
de Mao, Santo Domingo; Bowden, Jamaica (common). 
Cotypes.— Cat. Nos. 68722-68725, U.S.N.M. 
Order CYCLOSTOMATA Busk. 
Family HETEROPORIDAE Pergens and Meunier, 1886. 
Genus CERIOPORA Goldfuss, 1827. 
(For description, see Bulletin 106, U. S. National Museum, p. 678.) 
CERIOPORA VIRGINIANA, new species. 
Plate 26, figs. 1-3. 
Description. —The zoarium is an irregular globular mass. The tubes are 
polygonal; their walls are very thin. No peristomes. 
Affinities. —This species may be compared only with the European species 
from the faluns of Touraine not yet published. Only the figured specimen has 
been found. 
Occurrence. —Miocene (Yorktown formation): 1 mile northeast of Suffolk, 
Virginia (very rare). 
Rolotype. —Cat. No. 68726, U.S.N.M. 
Family DIASTOPORIDAE Gregory, 1899. 
Forma PROBOSCINA Audouin, 1826. 
PROBOSCINA MESLERI, new species. 
Plate 26, fig. 7. 
Description. —The zoarium incrusts shells and forms long triserial branches 
dividing almost at a right angle. The tubes are long, convex, distinct, porous. 
The peristomie is perpendicular to the zooecial axis. The apertura is orbicular 
and the peristome is thin and sharp. The apertures are arranged in quincunx or 
trigeminal. 
Measurements .— 
Diameter of orifice... 0.10 mm. 
Diameter of the tubes.... 0.12 mm. 
Diameter of aperture..... 0.40-0.50 mm. 
Zoarial width..... 0.40-0.45 mm. 
This species is named in honor of Mr. Rector D. Mesler, of the United States 
Geological Survey, who has made important collections of Miocene fossils for our 
study. 
Occurrence. —Miocene (Duplin marl): Wilmington, North Carolina (rare). 
Holotype.— Cat. No. 68727, U.S.N.M. 
