118 
Aug. F. Foerste 
mondensis makes its appearance in the Arnheim distinctly below 
the Dinorthis carleyi horizon, although locally the two fossils may 
be found associated. In Ohio, at Madison, in Indiana, and at the 
more northern localities in Kentucky on the western side of the 
Cincinnati geanticline, Leptaena occurs a short distance above a 
layer containing Platystrophia ponder osa. Farther southward, 
Leptaena and Platystrophia ponderosa are associated in the same 
layers. Still farther southward, Platystrophia ponderosa continues 
a considerable distance above the Leptaena richmondensis horizon, 
these conditions being prevalent throughout central Kentucky as 
far south as Lincoln, Casey, and Alarion counties. For the Arn- 
heim form of Leptaena, the term Leptaena richmondensis-precursor 
was proposed. (Bull. Denison Univ., vol. XIV, p. 211. See also 
the Ohio Naturalist, vol. XII, plate XXII, Fig. 7.) 
Leptaena richmondensis is not known in the lower or Fort 
Ancient division of the Waynesville member. In the middle or 
Clarksville division it makes its first appearance distinctly later 
than Strophomena planumhona and Strophomena sulcata. Near 
Blanchester and Clarksville, in Clinton county, Ohio, and near 
Fort Ancient, in Warren county, it makes its appearance quite 
constantly at feet below the lower Hehertella insculpta horizon, 
and continues from this level at various intervals as far as the 
base of the Liberty member. It occurs in the upper part of the 
Clarksville bed also northeast of Somerville, in the southern part 
of Preble county, and southwest of McGonigle in Butler county. 
Leptaena richmondensis is especially abundant at the lower 
Hehertella insculpta horizon, at the base of the upper or Blan- 
chester division of the Waynesville. It occurs at this horizon 
in southwestern Ohio, from Oxford, in Butler county, to Blan- 
chester, in the southwestern corner of Clinton county, wherever 
the lower Hehertella insculpta zone has been recognized. From 
this level it occurs at various intervals throughout the upper 
or Blanchester division. It is especially abundant in the Blan- 
chester division in Ohio, and in the more northern counties 
in the Ordovician areas of Indiana, as far west as Weisburg, 
and Moores Hill, in the western part of Dearborn county. From 
these areas it extends southward in smaller numbers. At Con- 
cord, in Lewis county, Kentucky, Leptaena richmondensis occurs 
between 19 and 22 feet below the top of the Blanchester division. 
At Sunset, in the western part of Fleming county, it is found 12 
