150 



low or very deep tangential sections the zooecia are thinner walled and 

 angular, and in the deep sections the mesopores appear to be more nu- 

 merous. 



In longitudinal sections the zooecia are seen to be thin-walled and 

 without diaphragms in the axial region, and gradually curving to the sur- 

 face, they emerge at right angles to the lattei". The mature region is 

 fairly deep and here the zooecia are thick-walled, except very close to the 

 surface. Diaphragms from 2 to S in each zoopcial tube, in the mature 

 region, one-half to two tube-diameters apart, the lirst one usually not 

 nearer than two tube-diameters to the surface of the zoariuni : more nu- 

 merous in the mesopores, which present a chain-like appearance. In the 

 submature region the acanthopores are thin-walle<I with a wide canal, 

 crossed by numerous diaphragms. The external portion of the walls of 

 the acanthopores as seen in longitudinal sections presents a spiny appear- 

 ance, due api)arently to an interrupted or periodic deposition of scleren- 

 cliynia. 



According to Bassler, Jiotosioiiui nirUiiiK is "aliundant in the Arnheim, 

 Waynesville, Liberty and Whitewater formal ions of the Richmond group 

 in Ohio. Indiana and Kciilucky."' It occurs in the Tanner's Creek section 

 rarely in the Arnheim and lower sixty feet of the Waynesville, and 

 abundantly in the upper thirty feet of the Waynesville and lower twcnt.\ 

 feet of the Lihcity loniiat ions. It does not occur in the ui)])er Lib- 

 erty, Saluda or Whitew.-iter formations in Indiana. Th(> Whitewater 

 form Is B. variahilc. B. rai-ians occurs in the base of the lyiberty near 

 Altington. AVayne Conuty. Indian.-i. ;nid in the .Vrnhcini and Waynesville 

 near Madison. 



B.\TOSTO>rA V.\IU.\I5ILE (I'lricli). 

 (IMatc II, figs. ]-lc: I'lata III, figs. 1-lc; IMato IV, figs. 1, la; rial<- VW. figs. 1-tc.) 

 fiiitosfoma rariahilr (i»ars). ITlrich, Geol. Surv. 111., Vol VIII, 1890, pi. 



xxxvi. Fig. I. (non pi. xxxvi. Figs. 4b, 4e, — B. varians). 

 liotostonia ravkihilv. Ras.sler, Proc. V. S. Nat. Mus., Vol. XXX, 1906, p. 



IS, pi. vii. Figs. 9, 10. 

 /Uitofttowa rariahilr. Cumings, Indian.-i Dept. Geo]. Nat. Res. 32d Ann. 



Rept., 1907. p. 777, pi. xxvi. Fig. ^?,. 

 Zoarium ramose, robust, cylindrical or subcylindrical, H to 20 mm. in 

 diameter, and 10 to 70 mm. long, dividing every 10 to 20 mm. either dichot- 

 omously or irregularly. The basal expansion forms large Irregular masse.? 



1 Proc. U. S. National Museum, vol. xxx, 1006, p. 18. 



