NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
125 
PERIPOROSELLA TANTILLA Canu and Bassler, 1917. 
Plate 24, figs. 7-12. 
1917. Periporosella tantilla Canu and Bassler, Synopsis American Early Tertiary Cheilo- 
stome Bryozoa, Bulletin 96, United States National Museum, p. 19, pi. 2, figs. 3, 4. 
The zoarium is free, formed by two lamellae joined together and inseparable. 
The zooecia are generally indistinct, very elongated, rectangular; the mural rim is 
broad, flat, enlarged at the base. The opesium is elliptical, somewhat enlarged 
distally, and very finely denticulated. The ovicell is deep but placed above the 
large distal septula; it projects but little exteriorly. The avicularia are inter - 
zooecial, rare, elliptical, without pivot, but with two lateral denticles; numerous 
dietellae in each zooecium. 
Measurements . — Opesia 
ho=0. 30-0.40 mm. 
Z<?=:0.11-0.19 mm. 
Zooecia 
(£■3=0.10-0. 50 mm. 
[73=0.25 mm. 
Variations . — In this species we have one of the most peculiar types of Mem- 
branipores. The dietellae arranged entirely around each zooecium (figs. 10, 11) 
are covered by an epithecal olocyst analogous to the olocyst of the mural rims in 
the Membranipores. These elements group themselves in a radial manner about 
the opesium (fig. 12). 
Another interesting peculiarity is the mode of gemmation of the zooecia which 
are arranged in parallel linear series, and every new row appears invariably on one 
of the free edges of the zoarium. 
The large distal septula opens in a dietella, which establishes communication 
with the succeeding zooecium, and its opening is often visible in the latter. 
This type of structure is different from all others on account of its dietellae, its 
method of gemmation, its ovicell, and even its avicularia. It certainly belongs to a 
family which our present zoological knowledge will not yet permit us to suspect. 
Occurrence . — Middle Jacksonian: Wilmington, North Carolina (common); 
near Lenuds Ferry, South Carolina (rare) ; Eutaw Springs, South Carolina (rare). 
Cotypes.— CM. No. 62577, U.S.N.M. 
Genus ELLISINA Norman, 1903. 
1903. Ellisina Norman, Natural History of East Finmark, Annals and Magazine Natural 
History, ser. 7, vol. 11, p. 596. 
The zooecia are furnished with avicularia, ovoid or triangular, situated on the 
hinder portion of the zooecium. The ovicell is well developed, typically with a 
flattened area on its front. In the type-species the pore-chambers (dietellae) are 
very large; one distal; the position of the remaining chambers is very unusual, 
the two front lateral pairs project outside the side walls; and the two posterior 
pairs are seen inside the side walls, which is the reverse of the usual rule. 
(Norman). 
Genotype. — M embranipora levata Hincks, 1882. 
Range. — Senonian-Recent. 
