58 KENTUCKY GEOLOGICAL SURVEY. 



conical or hemispheric form, from 3 or 4 nun. to 15 or more inm. 

 in height ; when free subglobular or irregularly globose in shape, 

 from 10 to 20 mm. in diameter when adult. Surface smooth 

 except for slightly elevated monticules of larger apertures; often 

 spinulose from the numerous strong acanthopores. Apertures 

 subpolygonal or subcircular, with numerous niesoppres in the 

 interspaces^ about 8 in 2 mm. Mesopores with closely set dia- 

 phragms. Zocecial tubes rather thin-walled, with numerous 

 cystiphragms and less numerous diaphragms. 



Occurrence : Abundant in the Waynesville beds of the Rich- 

 mond group in Ohio, Indiana, and Kentucky. In Ohio and In- 

 diana, the attached form is the common one. At Madison, Indi- 

 ana, and thence south through Kentucky, the free form is the 

 prevailing form. 



RHOMBOTRYPA QUADRATA (ROMIXGER). 



Plate 3, fig. 11. 

 Chaetetes quadratus. Rominger, Proceedings Academy of Natural Sciences 



of Philadelphia, p. 116, 18S6. 

 Monticulipora (Monotrypa) quadrata. Nicholson, Genus Monticulipora, p. 



179, fig. 36, 1881. 

 Chaetetes rhombicus. Nicholson, Paleontology of Ohio, vol. 2. p. 201, pi. xxi. 



12, 12a, 1875. 

 For full synonymy see Synopsis of American Fossil Bryozoa, Bulletin of U. S. 



Geological Survey, no. 173, p. 318, 1900. 



/ 



Zoarium ramose, branching frequently as a rule. Branches 

 cylindrical, from 4 to 10 mm. in diameter. Surface smooth. 

 Apertures polygonal, occasionally quite regularly hexagonal 

 and arranged in diagonally intersecting series, from 6 to 8 in 2 

 mm. In the immature region the zocecia are thin-walled, and 

 quadrate or rhombic in cross-section ; in the mature region the 

 walls are somewhat thickened and several diaphragms are de- 

 veloped. Neither mesopores nor acanthopores developed. 



Occurrence : This is one of the most abundant, characteristic 

 and widely distributed forms of the Richmond group. It is 

 easily recognized by the quadrate character of its zorecia, which 

 feature is usually visible in the cross-section furnished by the 

 broken-off ends of the branches. 



