Megalograptus welchi, S. A. Miller
By A. F. Foerste
Plate 58, figures 3–5
The Richmond group of Ohio, Indiana and Kentucky includes, in descending order, the following divisions:
| Elkhorn beds | Liberty beds |
| Whitewater beds | Waynesville beds |
| Saluda beds | Arnheim beds |
In Ohio, most of Indiana, and a part of northeastern Kentucky, the base of the Liberty bed is formed by a stratum in which the brachiopod Hebertella insculpta is very abundant. This stratum is overlain by one in which Plectambonites sericeus abounds, and at a still higher elevation Dinorthis subquadrata makes its first appearance.
The top of the Liberty bed is the horizon at which Gomphoceras eos, Gyroceras baeri, and several species of Cyrtoceras occur. Immediately below these cephalopoda, or associated in the same layers, a large form of Streptelasma rusticum is abundant.
The Liberty beds contain an interesting fauna. Ceraurus miseneri, Dalmanites breviceps, Brachiospongia tuberculata, and various crinoids occur here including Glyptocrinus richardsoni and Glyptocrinus fornshelli. The Liberty beds were a favorite collecting horizon for the crinoid hunters 40 years ago. It was while working out a pocket in which Dendrocrinus casei and Gaurocrinus onealli were abundant, that Megalograptus welchi was found. The locality occurs in the eastern edge of Warren county, Ohio. The road from Clarksville to Fort Ancient crosses Todds Fork half a mile west of Clarksville. A short distance beyond the point at which the road to Morrow turns off, on the left, is the home of Adam Pennington. The Megalograptus specimens were found about 100 yards directly west of the house, along a small stream. A wave-marked layer of limestone, 6 inches thick, overlies a few layers of limestone containing Dinorthis subquadrata. Farther down stream there are no exposures for about 25 feet, but it is evident from the stratigraphy worked out in the surrounding country, that the wave-marked layer here mentioned belongs about 15 feet above the Hebertella insculpta horizon. The Megalograptus occurred in a series of crinoid-bearing clays, 3 feet above the wavemarked limestone.
