626 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



the others and transverse (fig. 15) : its operculum probably closes the ovicell 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 zooecia (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 (Koschinsky) and of the Paris 

 Basin (Canu). Priabonian of the Vicentin (Waters). 



Plesiotypes.G&i. No. 64228, U.S.N.M. 



Genus SCHIZORTHOSECOS Canu and Bassler, 1917. 



1917. Schizorthosecos CANU and BASSLKK, Synopsis of American Early Tertiary Cheilostome 

 Bryozoa, Bulletin 96, United States National Museum, p. 74. 



The zoarium is cupuliform. The apertura is oval with a proximal rounded 

 rimule. There are numerous interzooecial zooeciules capable of being transformed 

 into avicularia, into radicular zooeciules, and into compensation zooeciules. The 

 ovicell is hyperstomial, placed on the distal zooecium and never closed by the oper- 

 culum. 



Genotype. Schizorthosecos (Orbitolites) interstitia Lea, 1833. 



Range. Claibornian Jacksouian. 



This genus is exclusively American ; it characterizes the Claibornian and the 

 base of the Jacksonian, where it is exterminated unexpectedly. 



It differs from Conescharellina D'Orbigny, 1851. and Bipora Whitelegge, 1887, 

 in its distinct zooecia and in the absence of lunoecia. 



SCHIZORTHOSECOS INTERSTITTA Lea, 1833. 



Plate 18, figs. 1-9. 



1833. Orbitolites interstitia LEA, Contribution to Geology. Philadelphia, p. 191. pi. 6. fig. 204. 



1862. Lunulitcs interstitia GAEB 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 GREGOBIO, Monographic Fauna Eoceuique de Ala- 

 bama, Annales de Geologie et de Paleontologie, Livr. 7 and 8, p. 249, pi. 42, figs. 

 16-22. 



1917. Schizorthosecos interstitia CASU and BASSLEB, 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 zooecia 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 avicularia 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 

 avicularia with pivot surround the ancestrula. 



