Jan., 1914,] Richmond Beds of the Cincinnati Group. 231 



minus, Calapoecia cribrifomiis, Hebertella sinuata, Platystrophia 

 acutilirata, Ischyrodonta truncata, Losphospira bowdeni, Liospira 

 sp., Bellerophon sp., Endoceras sp., Primitia glabra, Isochilina 

 subnodosa, Tetradella simplex, etc., etc. 



The Tetradium minus is rather scarce at Madison, but is 

 common I' above the second Columnaria reef toward Hanover, 

 and again above the mollusc layers 3 miles north. At the locality 

 five miles north it is very abundant through 7' of blocky, shaly 

 limestones, immediately above the limestones representing the 

 second reef. From here on this Tetradium horizon is very con- 

 stant, and occurs whereever the rocks have been exposed as far 

 north as Liberty, Ind. and as far toward the east as Oxford, O. 



A mile east of Liberty, where the Oxford pike crosses Hannah's 

 Creek, the Tetradium is scattered abundantly through the whole 

 4' 9" of Saluda rocks. Beneath are exposed 3' of shales and thin 

 limestones with much the same fauna as is carried by the same 

 strata at Laurel. 



North of Liberty only three miles, at the last long exposure 

 on Richland Creek, the Saluda strata have almost lost the Tetrad- 

 ium, and are distinctly shaly except at the top, where they end 

 in two heavy limestones, the lower one 1' 2" thick and very irregu- 

 lar, the top one 10" thick and more even. The top stratum is 

 composed largely of fossil "hash," and in this are water- worn 

 Rhyncotrema capax, etc. It occurs at this level to within four 

 miles of Oxford. Immediately above it are the characteristic 

 Whitewater strata and fauna. 



The lower shales are partly replaced by evenbedded limestones 

 along Elkhom Creek, and at the quarries along the Whitewater 

 River south of Richmond are represented by limestones indistin- 

 guishable from those below. But the top stratum is still heavy 

 and characteristic. 



While perhaps not strictly the equivalent of the second Colum- 

 naria reef, this Tetradimn reef developed immediately above it 

 and replaced it further north. Outside the Madison region it 

 bases the Saluda type of strata. 



Practically whereever this reef is seen it is closely associated 

 with a fauna similar to the one three miles north of Madison. 

 Sometimes this fauna is above the reef or in it, but usually is 

 beneath. Near Versailles the Dystactospongia is especially abun- 

 dant and just below it are found, besides the molluscs listed above, 

 Ptilodictya magnificia, Monticulipora epidermata, Leptaena 

 rhomboidalis, Agelacrinus cincinnatiensis, and Lichas sp. 



At Oxford, Ohio, the first incursion of the Whitewater fauna is 

 preserved in the 3' of Trochoceras shales, and among the clams 

 are such characteristic fonns as Byssonychia grandis, B. richmond- 

 ensis, Ischyrodonta elongata, I. truncata Opisthoptera casei, 

 Ortonella hainesi, and Whitella obliquata. 



