560 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



In the interior the aperture is semilunar and transverse with a slightly concave 

 proximal border. 



In examining the figures of Reuss we can note only a few differences of little im- 

 portance; the interareolar costules appear less salient and the avicularium there 

 appears smaller and more removed from the external aperture. At the most, our 

 specimens form a variety. 



Occurrence. Middle Jacksonian : Eighteen miles west of Wrightsville. Johnson 

 County, Georgia (rare) : Rich Hill. 5} miles southeast of Knoxville, Georgia (rare) ; 

 1-2 miles southeast of Marshallville, Georgia (rare) ; one-half mile southeast of 

 Georgia Kaolin Company Mine, Twiggs County, Georgia (rare). 



Geological distribution. In Europe the species occurs in the Latdorfian of 

 1/atdorf (Reuss). Rupelian of Germany (Reuss), Chattian of Germany (Reuss). 



D *ioo 



F75 



C* 



FIG. 167. Genus Adcona Lamouroux, 1816. 



A-F. Adeona violacca Johnston, 1S49. A. Portion of zoarium, X 22, showing numerous 

 marginal zooecia with frontal wall still uucalcified. B. Four zooecia, X 40, two of which have 

 the avicularium replaced by an elongated cavity which opens by means of a. round pore. C. Three 

 zooecia, X 40, viewed from the basal side after removal of the basal surface. The primary 

 aperture and the proximal margin of the secondary are visible. D. Aviculariau mandible, X 

 100. E. Two gonoecia, X 40. furnished with a cavity instead of an avicularium, like the zooecia 

 in fig. B. F. Operculum, X 75. The transverse oval part, somewhat more chitinized, corresponds 

 with the secondary aperture. (A-F after Levinsen, 1909.) 



These three are the substages of the Tongrian. Finally. Reuss cited it from the Tor- 

 tonian of Wieliezka in Pologne, but he did not give a figure. 

 Cotypes.Cnt. Xo. 64190. U.S.N.M. 



Genus ADEONA (Lamouroux, 1816) Levinsen, 1909. 



1909. Adeona LEVINSEN, Morphological and vSystematic Studies on Cheilostomatous Bryozoa, 

 p. 2S3. 



The frontal is perforated by an ascopore opening into the compensatrix. The 

 operculum is semilunar. The gonoecia are distinct and larger than the ordinary 

 zooecia. 



Genotype. Adeo-na (C ellepora) hf.ckell Reuss, 1847. 



