626 
BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 
the others and transverse (fig. 15) : its operculum probably closes the ovieell in 
opening, in order to facilitate the passage of the eggs. On the lower face (fig. 16) 
there are often some circular imbrications difficult to explain. In transverse sec- 
tion the zooeeia (fig. 18) are tubular; their peristomie forms a narrow gullet. 
Occurrence ; — Middle Jacksonian (Castle Hayne limestone) : Wilmington, North 
Carolina (common). 
Geological distribution. — Lutetian of Bavaria (Koseliinsky) and of the Paris 
Basin (Canu). Priabonian of the Vicentin (Waters). 
Plesiotypes. — Cat. No. 61228, IT.S.N.M. 
Genus SCHIZORTHOSECOS Canu and Bassler, 1917. 
1917. Schizorthosecos Cantj and Bassler, Synopsis of American Early Tertiary Cheilostome 
Bryozoa, Bulletin 96, United States National Museum, p. 74. 
The' zoarimn is cupuliform. The apertura is oval with a proximal rounded 
rimule. There are numerous interzooecial zooeciules capable of being transformed 
into avieularia, into radicular zooeciules, and into compensation zooeciules. The 
ovieell is hyperstomial, placed on the distal zooecium and never closed by the oper- 
culum. 
Genotype. — Schizorthosecos ( Orbitolites ) interstitia Lea, 1833. 
Range. — Claibornian — Jacksonian. 
This genus is exclusively American; it characterizes the Claibornian and the 
base of the Jacksonian, where it is exterminated unexpectedly. 
It differs from Gonescharellina D'Orbigny, 1851. and Bipora Whitelegge, 1887, 
in its distinct zooeeia and in the absence of lunoecia. 
SCHIZORTHOSECOS INTERSTITIA Lea, 1833. , 
Plate IS, figs. 1-9. 
1833. Orbitolites interstitia Lea, Contribution to Geology. Philadelphia, p. 191, pi. 6, fig. 204. 
1862. Lunulites interstitia Gabb and Horn, Monograph fossil Polyzoa Secondary and Tertiary 
formations North America, Journal Academy Natural Sciences, Philadelphia, ser. 2, 
vol. 5, p. 120. 
1890. Lunulites ( Cupularia ) interstitia De Gregorio, Monographic Fauna Eoc-enique de Ala- 
bama, Annales de Geologie et de Paleontologie, Livr. 7 and 8, p. 249, pi. 42, figs. 
16-22. 
1917. Schizorthosecos interstitia Canu and Bassler, Synopsis of American Early Tertiary 
Cheilostome Bryozoa, Bulletin 96, United States National Museum, p. 75, pi. 6, 
figs. 4, 5. 
Description. — The zoarium is cupuliform, little deep. The zooeeia are distinct, 
tubular, erect, terminated by a narrowed peristomie. The apertura is placed at 
the base of the peristomie; in its rimule, it often has a flat lyrula; the peristomice 
is of the same form as the apertura. Between the peristomes, on the external sur- 
face, there are numerous zooeciules, which are transformed according to their 
position into radicular zooeciules, into avieularia with pivot, or into compensation 
zooeciules. On the inner face each zooecium is indicated by a hexagon perforated 
with six to ten large tremopores, which are the orifices of long tubules; some large 
avieularia with pivot surround the ancestrula. 
