Strophomena and Other Fossils 51 
Sandy-appearing limestone 5 ft. 
Platystrophia ponderosa moderately abundant except toward base. . . .23 ft. 
Strophomena maysvillensis rather common 1 ft. 
Limestone with Strophomena maysvillensis not common 19 ft. 
Limestone with some thin sandy-appearing layers 15 ft. 
Rough limestone full of Strophomena maysvillensis 9 ft. 
Base of Fairmount. 
Exposures poor, with Strophomena maysvillensis , Platystrophia pro- 
fundosulcata-hopensis, a few specimens of Dalmanella multisecta, 
Constellaria florida, Callopora nodulosa 11 ft. 
Top of zone with Dalmanella multisecta abundant. 
North of the Ohio River, in Indiana, Strophomena planocon- 
vexa and its relative Strophomena maysvillensis occur in much 
smaller numbers and are restricted in their vertical range chiefly 
to two horizons, separated by a considerable interval in which 
no representatives of these species are known. 
Similar features are presented at Williamstown, in Grant county, 
Kentucky. Here, along the railroad north of the town, Stropho- 
mena planoconvexa occurs at two horizons separated by an inter- 
val of 6 feet, and Strophomena maysvillensis is found about 30 
or 35 feet lower, being abundant in a section about feet thick. 
The Strophomena planoconvexa horizon unquestionably is of Fair- 
mount age. It Atactoporella sp., Calloporasp., Constel- 
laria florida, Constellaria plana, Dekayia aspera, Heterotrypa sp., 
Homotrypa ciirvata, and Perenopora sp. 
At the Strophomena maysvillensis horizon, Amplexopora sep- 
tosa, Callopora nodulosa, Dekayella ulrichi, and Heterotrypa sp. 
were collected. These suggest the base of the Mount Hope 
horizon, Dekayella ulrichi being regarded as limited to the Eden 
beds. 
Strophomena occurs near the base of the Mount Hope and at 
the base of the Fairmount bed also in southern Indiana. 
An eighth of a mile west of Brooksburg, in the southeastern 
part of Jefferson county, Indiana, Strophomena occurs 7| feet 
above the horizon at which Dalmanella multisecta is very common. 
At Vevay, in the southern part of Switzerland county, the top 
of the Eden contains Dekayella ulrichi, associated with very abun- 
dant specimens of Dalmanella multisecta. In the immediately 
overlying layers, Platystrophia profundosulcata-hopensis occurs. 
Strophomena ranges from 2 to 12 feet above the base of the Mays- 
ville. At several levels within the same range, Plectorthis neglecta 
