Richjiwiid Group of Cinciiuiati Aiitichiic. — Focrsfc 339 
cur in the middle and upper part of the Lower Richmond. At 
Concord in Kentuck}-, specimens having the same general 
form as Strophouicna nutans are found at the base of the Dal- 
uuviclla jugosa zone, eighteen feet below the lowest specimens 
of Stroplionicna rugosa. Many of these specimens attain 
a length of one inch and a width along the hinge-line of an 
inch and a quarter. The strise of both valves are fine ; some 
are more prominent, three to six intermediate stride being less 
conspicuous. About six to nine of the more prominent stride 
occur in a width of a quarter of an inch. 
Tlic top of the Lozi'cr Richmond. 
At the bridge across Todd's Fork, northwest of Clarksville, 
Ohio, DalniancUa jugosa occurs sparingly in the clayey lime- 
stone at the base of the section. Immediately above, it be- 
comes very common, and remains common as far as forty to 
forty-three feet above the level of the creek. Forty feet above 
the creek there is a wave-marked layer of limestone, with the 
ridges trending approximately northeast and southwest. Fifty 
feet above the creek, HcbcrtcUa insculpta is rather common, 
but is restricted to only a few feet in the vertical section. Dal- 
nianclhi jugosa occurs sparingly up to this level, and even for 
five or more feet above the same. 
The Hebertclla insculpta horizon may be regarded as form- 
ing the top of the Lower Richmond. It has not yet been defi- 
nitely determined that this fossil is restricted to the top of the 
Lower Richmond, but it is known at least to be quite constant 
in its appearance at this horizon in northeastern Kentucky, all 
of Ohio, and in Indiana as far south as Weisburg and Ver- 
sailles. It may be that it occurs as far south as Madison but 
no specimens have been collected there. 
At \'ersailles, in Indiana, Ryncliotrcnia dcntatuni mal-es 
its first appearance in the Lower Richmond at a level one or 
two feet beneath that of Hehertella insculpta. At Dayton, 
Ohio, and at Richmond. Indiana, ibs range extends to the top 
of the Middle Richmond. While it is not known to occur in 
the lower part of the Lower Richmond, a very similar, if not 
identical form has been found in the u])per part of the Warren 
bed half a mile southeast of Howard's mill in Montgomery 
county, Kentucky. It jiossesses three distinct plications antl one 
indistinct j^licaticn on each side of the dorsal fold instead of 
