NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
761 
The ovicell which we have discovered is not complete, but it indicates suf- 
ficiently (fig. 15) that this species is a Platonea 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 lamelliferous zoarium. 
It differs from Idmonea arcuata , new species and Idmonea petri D’Archiac, 
1846, in its much larger micrometric dimensions. 
Occurt'ence. — Lower Jacksonian: Three and one-half miles southeast of Shell 
Bluff post office, Georgia (common). 
Cotypes. — Cat. No. 65340, U.S.N.M. 
CENTRONEA, new genus. 
Greek : ksntron , 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. — Centronea ( 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 Aotinopora. All the 
known ovicelled species of Aotinopora belong to a different family and we are 
therefore unable to longer employ this old term of nomenclature. 
B 
Fig. 249. — Centronea , new genus. 
A, B. Views natural size and en- 
larged of a composite zoarium of 
Centronea (Multitubigera) micro- 
pora, Reuss, 1869. 
CENTRONEA MICROPORA Reuss, 1869, variety. 
ITate 135, figs. 1-15. 
1869. Multitubigera niicropora Reuss, Palaoutologisclie Studien fiber die alteren Terti- 
arschichten der Alpen, II Abtheilung, Die fossilen Anthozoen und Bryozoen der 
Schichtengruppe von Crosaro, Denkscliriften der k. Akademie der Wissenschaften, 
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. 
