NORTH AMERICAN EARLY TERTIARY BRYOZOA. 



761 



The oviooll which we have discovered is not complete, but it indicates suf- 

 ficient!}' (fig. 15) that this species is a Platonca and not an Idmonea because of the 

 presence of the interfascicular lobes and the special position of the oeciopore. 



Affinities. This species differs from the recent Tubulipora serpens in its free 

 and Inmelliferous zoarium. 



It differs from Idmonea arcuata, new species and Idmonea, petri D'Archiac, 

 1846, in its much larger micrometric dimensions. 



Occurrence. Lower Jacksonian : Three and one-half miles southeast of Shell 

 Bluff post office, Georgia (common). 



Cotypes.Csit. No. 65340, U.S.N.M. 



CENTRONEA, new genus. 



Greek : kentron, center, referring to the position of the ovicell. 

 The ovicell is lobate, subsymmetrical, median, suborbicular. The fascicles are 



projecting very little above the ovicell. 



Genotype. Gentronea (Multitubigera) mi- 

 cropora Reuss, 1869. Priabonian. 



As we do not know the oeciopore, the differ- 

 ence between this genus and Platonea is little 

 important, but Centronea differs in the form of 

 the ovicell, which is perhaps only in consequence 

 of the orbicular form of the zoarium. As a con- 

 trary argument is also reasonable we prefer to 

 recognize this genus. 



Our specimens correspond exactly to the 

 genus Multitubigera D'Orbigny, 1850, in their 

 zoarial form. Following our custom we reserve 

 this old name for the nonovicelled species. On 

 the other hand, Multitubigera is formed of ag- 

 glomerate subcolonies of Actinopora. All the 

 known ovicelled species of Actinopora belong to a different family and we are 

 therefore unable to longer employ this old term of nomenclature. 



CENTRONEA MICKOPORA Reuss. 1869, variety. 



Tlato 135, figs. 1-15. 



1SGO. MuJtitu'bigera micropora KEUSS, Paliiontologische Stndien uber die alteren Terti- 

 arsehichten der Alpen, II Abtlioilung, Die fossilen Anthozoen uncl Bryozoen der 

 Schichtengruppe von Crosaro, Denksclirifteu der k. Akademie der Wissenscliai'ten, 

 Wien, vol. 29, Abth. 1, pi. 34, fig. 15. 



Description. The zoarium is formed by the agglomeration of discoidal sub- 

 colonies superposed and joined by their germinal layer. The fascicles are salient, 

 radiating,, pluriserial, arranged around a more or less large center. The tubes are 

 invisible; the peristomie is elevated vertically; the peristome is thin and orbicular. 



FIG. 249. Centronea, new genus. 



A. B. Views natural size and en- 

 larged of a composite zoarium of 

 Centronea (Multitubigera) micro- 

 Reuss, 1869. 



