NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 207 
heights, separated by a thick continuous cuticle; the orifice is polygonal with 
salient peristome. The ovicell is large, irregular, surrounding a score of tubes. 
Variations. —The form of the zoarium is quite variable, but it is always a small 
globular mass simple or mammillated. It grows either on shells or on algae. The 
small pores observed on the surface of the zoarium are not mesopores but are young 
tubes in process of formation. The diameter of the normal apertures varies from 
0.12 to 0.15 mm. 
In longitudinal section the zooecial walls are not vesicular; they show along, 
minute canal corresponding to the disappearance of the cuticle which surrounded 
the tubes on a living specimen. 
Affinities. —This species differs from Tretocycloecia tortilis Lonsdale, 1845, in 
its nonarborescent zoarial form, in the smaller zooecial diameter, and in its larger 
ovicell. 
Occurrence. —Pliocene (Waccamaw marl): Waccamaw River, Horry County, 
South Carolina (very rare). Miocene (Duplin marl): One-half mile above Eden- 
house Point, Chowan River, and 10 miles south of Greenville, North Carolina (rare). 
Cotypes. —Cat. Nos. 68756-68757, U.S.N.M. 
Genus PSILOSOLEN Canu and Bassler, 1922. 
1922. Psilosolen Canu and Bassler, Studies on Cyclostomatous Bryozoa, Proc. U. S. National 
Museum, vol. 61, p. 112. 
There are no adventitious tubes. The tubes are cylindrical with peripheral 
gemmation. 
Genotype.—Psilosolen capitiferax, new species. 
Range. —Pleistocene, Recent. 
The ovicell is a swelling perforated by the tubes as in the Diaperoeciidae, but 
it is not inserted in the tubes themselves. On the contrary, the ovicell is per¬ 
pendicular to the tubes and surrounds only the peristomes as in the family Tre- 
tocycloeciidae, where this new genus may be naturally classed. The ovicell is 
little convex and very different from the elongated and very salient sac of the 
Ascosoeciidae. 
It is remarkable to note again that through the geological ages it is the simplest 
form of the family that has persisted. The Cretaceous and Tertiary genera of this 
family are provided with adventitious tubes. 
PSILOSOLEN CAPITIFERAX, Canu and Bassler, 1922. 
Plate 44, figs. 11-21. 
1922. Psilosolen capitiferax Canu and Bassler, Studies on Cyclostomatous Bryozoa, Proc. U. S. 
National Museum, vol. 61, p. 112, pi. 13, fig. 8. 
Description. —The zoarium is free, with the form of Entalophora, more or less 
compressed, dichotomous; the extremity of the branches is enlarged, flattened, and 
hears the ovicell. The tubes are visible, separated by a furrow, convex, wrinkled 
transversely, somewhat widened at the summit; the peristome is thin, salient, 
elliptical or suborbicular. The ovicell is a swelling covering the extremity of a • 
branch; it is perforated by a dozen tubes, some of which are closed by a finely porous 
diaphragm. 
