366 The American Geologist. December, 1902. 
pliia is fully as large as the form of Platystropliia lynx which is 
characteristic of the Mount Auburn bed in the upper third of 
the Lorraine as defined by John M. Nickles. The form most 
characteristic of the Mount Auburn bed has a hinge line con- 
siderably shorter than the greatest width of the shell. The 
bed contains also a second form, with a hingeline equaling or 
exceeding the greatest width of the shell. This form occurs 
not only in the Mount Auburn bed, but also in the overlying 
\\'arren bed, and in the underlying Corryville bed. It is this 
more widely distributed form of Platystrophia lynx which oc- 
curs in the massive bed along the Cumberland. Both forms 
are confined to the upper half of the Lorraine in Ohio, Indi- 
ana, and Kentucky ; they do not occur in the Richmond. Hence 
the massive bed is identified as Lorraine. Heterospongia siib- 
rainosa occurs both in the Richmond and in the upper Lor- 
raine in Marion county, Kentucky. 
Below the massive bed occurs a clayey calcareous rock 
which often forms high steep blufifs at the river's edge. It 
contains the same form of Platystrophia lynx as the massive 
bed immediately above, but the form occurs in vastly greater 
numbers, being occasionally abundant at all levels ; usually 
however they are common only at lower levels and are much 
less common or even absent in the upper third of this bed. The 
bed is referred to the upper half of the Lorraine. Its total 
thickness is unknown. Northwest of Thomas branch only the 
upper 17 feet of this bed are exposed. Farther down the river^ 
however, occur sections in which this bed equals and exceeds 
50 feet in thickness. 
Below the Platystrophia beds occur a series of less clayey 
layers, often consisting of fairly well bedded limestone. TwO' 
miles above Rowena, at the beginning of the high cliffs on the 
north side of the river just below Masons branch the lime- 
stone contains Orthorhynchula linneyi. This species seems to 
occqr also in the same limestone southeast of the Horseshoe 
bottom, half a mile east of Difficult creek. This form is char- 
acteristic of the Fairmount bed in the lower half of the Lor- 
raine. Hence the limestone along the Cumberland, in which 
the Orthorhynchula is found is identified with the lower Lor- 
raine. This limestone contains more numerous and a greater 
variety of fossils than any other part of the Ordovician sec- 
tion along the crest of the anticline in southern Kentucky. 
