86 
Aug. F. Foerste 
specimens of Strophomena subtenta, with the oblique wrinkles 
and subequal striae, were found more frequently in the lower 
part of the Liberty, for instance at Concord, Kentucky; at Clarks- 
ville, near Dayton, west of Camden, and near Oxford, Ohio; also 
at Richmond, and thence southward to the mouth of Bull Creek, 
in Indiana. While especially common in the lower half of the 
Liberty bed, it is found also in the upper half of the Blanchester, 
and in the Clarksville division, its range being coterminous with 
that of typical Strophomena planumbona. In the other direc- 
tion, upward, it is found as high as the top of the Liberty. 
Among specimens of Strophomena planumbona without the 
oblique wrinkles, there is every variation at the same horizon 
from subequal striae to those with every second or fourth stria- 
tion distinctly more prominent. Moreover, the oblique wrin- 
kling occurs both in the subequally and in the unequally striated 
shells, so that it has been found impossible to make use of either 
feature or of both combined in the discrimination of Strophomena 
subtenta from Strophomena planumbona in the field, not from 
selected specimens. 
The type of Strophomena subtenta came from the vicinity of 
Oxford, Ohio. While Dalmanella jugosa {Or this testudinaria of 
Hall) is common in the Fort Ancient and Clarksville divisions 
of the Waynesville bed, and practically is absent above the middle 
of the Blanchester division, it by no means follows that the type 
of Strophomena subtenta came from the Clarksville division of 
the Waynesville. At the time of the original description of that 
species, the various horizons of the Cincinnatian fossils were not 
as carefully discriminated as later, and the fact that Strophomena 
subtenta occurred in the same general neighborhood as Dalma- 
nella jugosa might have been considered sufficient to regard them 
as associated. 
While the exact horizon from which the type of Strophomena 
subtenta was obtained is somewhat in doubt, there is no uncer- 
tainty about that of Strophomena plicata, Meek, since no strata 
below the Liberty are exposed near the base of the hills at Rich- 
mond, Indiana. The nearest exposure of the upper Hebertella 
insculpta horizon, at the base of the Liberty, below the lowest 
exposures containing Dinorthis subquadrata, occurs 4 miles down 
the river, from Richmond, a quarter of a mile east of the mouth 
of the Elkhorn Creek, in the lowest exposures on that stream. 
