100 
Aug. F. Foerste 
larger specimens may vary from 26 to 30 mm. The postero- 
lateral outlines are either rectangular or slightly extended along 
the hinge-line. The brachial valve is almost evenly convex, the 
flattening at the beak being inconspicuous. In a corresponding 
manner, the concavity of the pedicel valve is comparatively 
uninterrupted at the beak, the convexity immediately anterior 
to the beak usually being inconspicuous. The convexity of the 
brachial valve equals 8 mm. in shells 33 mm. in width. 
In the original description, the type specimens are stated to 
have come from the upper part of the Cincinnati group, in Ohio 
and Indiana. In the James collection, preserved in the Walker 
Museum, at Chicago University, a series of specimens, numbered 
1567, is labelled as forming the types of Strophomena vetusta, 
and as coming from Blanchester, Ohio. An examination of these 
specimens suggests that they are characteristic Liberty or White- 
water forms, and not the form from the Blanchester division of 
the Waynesville bed, here called Strophomena vetusta-precursor. 
Of these types, four are illustrated by Figs. 2 B, C, D, and E, on 
plate VI of this Bulletin. 
The first appearance of Strophomena vetusta is in the Blan- 
chester division of the Waynesville, where it bears the name 
Strophomena vetusta-precursor, and where the valves are distinctly 
thinner than in the more typical specimens, found in the Liberty 
and Whitewater beds. At those localities at which Strophomena 
planumbona, or Strophomena planumbona-suhtenta, is very abun- 
dant in the lower part of the Liberty, Strophomena vetusta comes 
in near the middle of the Liberty and does not become abundant 
until the upper part of the Liberty is reached. This appears to 
be true at Concord, Kentucky, and near Clarksville, Camden, 
and elsewhere in Ohio. In the Whitewater bed, however, it 
ranges from the base to the top. 
On the eastern side of the Cincinnati geanticline, Strophomena 
vetusta has been identified with certainty as far southward as 
Wyoming, in the southern part of Fleming county, and with 
considerable probability as far as College Hill, in the northeastern 
part of Madison county. From Wyoming southward, its ver- 
tical range appears to be in the Liberty. Northward, in Ohio 
and Indiana, it occurs also in the Whitewater bed. 
On the western side of the Cincinnati geanticline, in Kentucky, 
Strophomena vetusta can be traced as far southward as Bardstown, 
