8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



rich. The locality was given by Nicholson as "Cincinnati Group, 

 Ohio," and the depository of the primary types is unknown. 



Material studied. — The assumption is made here that the primary 

 types came from the Southgate member in the Cincinnati region. The 

 description below is based on specimens from that member identified 

 as B. implicatiim in the U. S. National Museum collections, plus 

 specimens collected by the author, as follows : 



U.S.N.M. 2994: Southgate member, Chesapeake and Ohio Rail- 

 road cut on northeast slope of Bald Knob on west side of Mill Creek, 

 Cincinnati, Ohio, collected by R. Boardman. Sections from 9 frag- 

 mentary zoaria studied. 



U.S.N.M. 2995: Southgate member, 150 feet above river, head 

 of Monmouth Street, Newport, Ky. Collector unknown. Sections 

 from 9 fragmentary zoaria were studied. 



U.S.N.M. 2999: Southgate member, Shadwell Street, Cincinnati, 

 Ohio. Collector unknown. Sections from 10 fragmentary zoaria were 

 studied. 



U.S.N.M. catalog numbers of illustrated specimens are 138266- 

 138272. 



Description. — Zoaria are ramose, incrusting, or a combination of 

 these two growth habits. Branches are circular to elliptical in cross 

 section. Secondary overgrowth is characteristically well developed 

 on ramose zoaria, as many as four layers occurring on older branches. 

 Irregular development of overgrowths, especially their ramose ex- 

 tensions beyond primary branches, produces anastomosing branches 

 that display erratic and confused zooecial growth at surfaces where 

 branches are joined. Lateral branches arising from overgrowths are 

 commonly discordantly small in diameter and random in arrange- 

 ment. Local patches of more extended zooecial growth or abrupt 

 changes in direction and diameter of secondary branches beyond the 

 ends of primary branches produce localized swellings on the branches 

 that are characteristic of the species. 



Monticules are generally flush with the surface of the zoarium 

 and the monticular zooecia are little different from intermonticular 

 zooecia. 



In the endozone, zooecial walls are thin, dark, and somewhat granu- 

 lar in appearance. The zooecia are extremely variable in width and 

 irregular in direction, bending in and out of the planes of longitudinal 

 thin sections. Partitions transverse to the zooecia are common but 

 irregularly distributed and are planar or curved. Many zooecia seem 



