Strophomena and Other Fossils 
53 
the upper part of the road ascending the hill east of Scott Chapel,, 
along the eastern branch of Lock Lick Creek, 2 miles east of 
the J. W. Evett locality, or 3 miles north of Florence, in Switz- 
erland county. At the latter locality the upper Strophomena 
horizon is underlaid by thin-bedded, argillaceous, sandy, brown 
shale, and this thin-bedded shaly material occurs at many localities 
in the same county at the same horizon, apparently the upper half 
of the Mount Hope bed. 
At the lower horizon, in Indiana, the specimens of Strophomena 
are small, they have a more convex brachial valve and are regarded 
as more closely allied to Strophomena maysvillensis. At the upper 
horizon, the specimens of Strophomena are larger and flatter, and 
are regarded as Strophomena planoconvexa. 
At most places, in Ohio, Strophomena occurs chiefly at the base 
of the Fairmount rciember, and, in fact, Strophomena planocon- 
vexa was used by Mr. John M. Nickles to mark the plane between 
the Mount Hope and the Fairmount. Occasionally, however, 
Strophomena occurs also here at two horizons. For instance, at 
Allandale, 10 miles northeast of the center of Cincinnati, Stro- 
phomena planoconvexa occurs at the base of the Fairmount, while 
at a road crossing the railroad half a mile eastward, Strophomena 
maysvillensis occurs at a lower level in the Mount Hope. 
Strophomena maysvillensis occurs in considerable numbers also 
along the Cumberland River, from the northwestern corner of 
Wayne county to the northeastern part of Cumberland county. 
Here it is associated with Orthorhynchula linneyi, Escharopora 
hilli, and Cyrtoceras vallandinghami, all indicating the top of the 
Fairmount as exposed in central Kentucky. Strophomena mays- 
villensis, associated with Orthorhynchula linneyi, is found also in 
Tennessee, occurring as far south as the area covered by the 
Columbia folio. 
Strophomena maysvillensis is known at present from Tennessee, 
Kentucky, Ohio, and Indiana. In Kentucky, it is most abundant 
and of largest size in the central part of the state and thence north- 
eastward as far as Alaysville. Aloreover, in this part of the state 
it begins its range as low as the base of the Mount Hope, while 
northward and northwestward it is rare or absent until the top of 
the Alount Hope is reached. These facts suggest the derivation of 
Strophomena maysvillensis from some southern source. It may be 
