344 The American Geologist. "^""^' ^^^^• 
teen feet below the Clinton. In the valley of Whitewater river 
John Misner found two speeimens of C. ahcolata near the base 
of the Middle Richmond, and two equally large specimens of 
Calopoccia crihriforiuis were found, one near the base and the 
other near the top of the Middle Richmond. 
Wherever, in Indiana, the horizon of the coral reef exposed 
at Madison can be determined, or wherever Tetrad in m iiiinus 
forms a well marked zone at practically the same horizon, the 
base of these beds is considered the paleontological base of the 
Upper Richmond. 
A great coral reef, made up of numerous specimens of 
Columnaria ahcolata, Columnaria halli, and Calopoccia cribri- 
formis is found also in central Kentucky, in Nelson, Marion, 
and Washington counties. It occurs at the base of the Rich- 
mond section as exposed in that part of the state. This coral 
bed in central Kentucky probably was not synchronous with 
the coral bed in southern Indiana. Although the lower and 
middle beds of the Richmond stage thin out rapidly southward, 
so many Middle Richmond fossils occur in the lower part of 
the Richmond section in central Kentucky, just above the coral, 
bed, that it seems probable that the coral reef of central Ken- 
tucky is of earlier date than the coral reef at the base of the 
Upper Richmond in southern Indiana. 
While the base of the Upper Richmond at many localities 
in southern Indiana is characterized by the presence of numer- 
ous specimens of CohLinnaria ahcolata, Columnaria halli, Cal- 
opoccia cribriformis, and Tetradinui minus, none of these fos- 
sils are confined tO' this horizon.* 
Columnaria aheolata occurs in the Black River limestone 
of Ontario, and in the Trenton formation of Manitoba and of 
the district of Mackenzie. It is found at the top of the Lor- 
raine, associated with Dinorthis rctrorsa, at Clifton, Tennessee. 
Small specimens, three inches in diameter, occur above He- 
bcrtella insculpta at Concord, Ky. Small specimens are found 
also in the lower half of the Middle Richmond, on East Fork 
of 'i odds Fork, Ohio, and fifteen feet below the base of the Clin- 
* "A rfvision of genera and species of Canadian paleozoic corals," L. M. 
Lambe, 1901. pp. 43. 90. 93, 98. 100, 110. 
The Cincinnati Group in Western Tennessee, Jour/ia/ of Geology, 1903, 
p. 37. 
"Corals from the Lower Silurian oi lAxnuesota," Geology of Minn., vol. 
jii, part 1, Winchell and Schuchert, pp. 85, 93, 94. 
