NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
837 
The mesopores are small, polygonal, separated by thick walls, grouped in trans- 
versal zones, alternating with the zones of the peristomes, and (in section) with 
vesicular walls and often ramified. 
Diameter of the peristome 0.14 mm. 
Diameter of the apertura -. 2 -_ 0.10 mm. 
Measurements.- Diameter of the brand)es 4.00 mm. 
Diameter of the cancelli 0.06 mm. 
This species was noted in 1882 1 by Ulrich, who discovered the nature of the 
tubes and mesopores of Zonopora. 
We have not discovered the ovicell, so our generic reference is quite doubtful. 
The resemblance of this species to Zonopora ligeriensis D’Orbigny, 1853, has 
caused us to classify it provisionally in our new genus. 
We know that the large zones of mesopores are formed by their branching; 
but the latter appears to be rather irregular, so that the longitudinal sections are 
always somewhat confused. 
Affinities. — This species differs from Tretocycloecia reticulata in its somewhat 
smaller micrometric measurements. 
Occurrence. — Midwayan (Clayton limestone) : Mabelvale, near Little Rock, 
Arkansas (rare). 
Cotypes. — Cat. No. 65261, U.S.N.M. 
POLYASCOSOECIA, new genus. 
The ovicell is globular, salient, spread between the fascicles whose length it 
alignments, placed eccentrically on the frontal. The tubes are cylindrical, oriented, 
short; they ramify into numerous mesopores on the frontal. The dorsal of the 
zoarium is thick, with lamellar structure, and perforated by vacuoles bent 
toward the base. 
Genotype. — Polyascosoecia coronopus , new species. 
Range. — Eocene-Pliocene. 
Further remarks upon this new genus and a description of the genotype are 
included in a study of the cyclostomatous bryozoa now in press. 
This genus differs from Pleuronea in which the ovicell is placed identically, 
not only in the different nature of the ovicell. but in its cylindrical tubes. 
It differs from the genus Erkosonea , equally provided with pores on the two 
faces of the zoarium, in its ovicell placed laterally, and in its short cylindrical tubes. 
POLYASCOSOECIA JACKSON1CA, new species. 
Plate 134, figs. 1-21. 
Description . — The zoarium is free, bifurcated, or dichotomous, with triangular 
section, often reticulated. The fascicles are very little salient, composed of four 
tubes, arranged alternately on each side of the median crest and quite close to it. 
1 1882. Journal Cincinnati Society Natural History, p. 143. 
