NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
479 
Genus CYSTISELLA Canu and Bassler, 1917. 
1917. Cystisella Canu and Bassler, Synopsis American Early Tertiary Gheilostome Bryozoa, 
Bulletin 96, United States National Museum, p. 53. 
The frontal is an olocyst. It bears a very wide avicularian chamber in which 
there is a pair of large glands. The mandibles have a lucid'a in the middle. 
(Waters). 
Genotype. — Cystisella ( Porella ) saccata Busk, 1856. 
Range. — Midwayan-Recent. 
“In Porella saccata it [the ovicell] is many layered, as thin calcareous layers, 
presumably gymnocyst [our olocyst] layers, continually grow over the ooecium, not 
only from the distal zooecium but also from the two neighboring zooecia, and 
we can see as a rule three, distinctly separated, thin covering plates on their sur- 
face.” (Levinsen, 1909, p. 836.) 
CYSTISELLA MIDWAYANICA Canu and Bassler, 1917. 
Plate 8, figs. 5, 6. 
1917. Cystisella midivayanica Canu and Bassler, Synopsis American Early Tertiary 
Clieilostome Bryozoa, Bulletin 96, United States National Museum, p. 53, pi. 5. fig. 6. 
Description. — The zoarium incrusts shells. The zooecia are distinct, somewhat 
elongated, hexagonal, separated by a furrow or a thin salient thread ; the frontal is 
very convex and very finely granulated. The peristome is thin, little salient in its 
distal part; it bears some spines; the peristomice is elliptical and deformed inte- 
riorly by the avicularium. The avicularium forms a long chamber, median and 
conical; its orifice is little circular and turned toward the apertura. 
Measurements . — Peristomice | f mm ‘ 
U/>e=0.14mm. 
Zooecia 
[Zs=0.40 mm. 
ife=:0.30mm. 
Occurrence . — Midwayan (Clayton limestone) : Luverne, Crenshaw County, 
Alabama (very rare) ; one mile west of Fort Gaines, Georgia (rare). 
Cotypes. — Cat. No. 62606, U.S.N.M. 
Genus PORELLA Gray, 1848. 
1848. Porella Gray, List of British Animals in collection British Museum, Centroniae, 
pp. 127, 148. 
The ovicell opens into the peristomie; it is porous, imbedded in the distal 
zooecium. The apertura is semilunar. Neither lyrula nor cardelles. The oper- 
culum is almost straight in its proximal part, with rounded corners; there is a 
muscular prominence a little distance from the edge. In front of the apertura 
there is an avicularium; the mandible is semicircular and has well marked thick- 
enings formed of diagonal bars. The frontal is a tremoevst with tubules. 20 tenta- 
cles. 
Genotype. — Porella (Millepora) cervicornis Pallas, 1766. 
Range. — Lutetian-Recent. 
