Ripley Island Area of Southern Indiana. 331 



bed, 10 feet thick, contains Byssonychia ohesa, Ctenodonta 

 cingulata, a form of Hehertella occidentalis in which the 

 median depression of the brachial valve is fairly distinct toward 

 the beak but nearly obsolete anteriorly, a variety of Platy- 

 strophia of medium size with the hinge line equalling or only 

 slightly exceeding the general width of the shell, Streptelasma 

 r%isticum, and Protarea vetusta. 



The same fauna, with the addition of Schizolopha moorei 

 and Streptelasma divaricans, occurs 2 miles northwest of Ver- 

 sailles, where a branch of Cedar creek crosses the old road 

 from Versailles to Osgood. It is seen also one mile northeast 

 of Osgood south of the right of way formerly occupied by the 

 Baltimore and Ohio Southwestern railroad, in a quarry. Here 

 in addition to the fossils near Versailles are found Crania 

 scahiosa, Trematis millepunctata, Hehertella occidentalis 

 typical form, Hehertella sinuata, Strophomena sulcata, and 

 Rafinesquina alternata. At the quarry the lower part of the 

 section consists of limestone, which is equivalent to the upper 

 part of the massive bed at Madison, and to the upper part of 

 the exposure at the northern edge of Versailles. The over- 

 lying section, at least 13 feet thick, contains the fossils just 

 enumerated. Immediately above occur layers of limestone in 

 which are found structures which either are concretionary or 

 are specimens of Strephochetus or Gifvanella, varying between 

 a quarter and a half inch in diameter. This layer is better 

 exposed a quarter of a mile southwest along the same stream, 

 nearer town. Immediately overlying this layer are thin lime- 

 stones interbedded with clay, a section about 8 feet thick, con- 

 taining Hehertella sinuata, Platystrophia Madisun bed form, 

 Strophomena sulcata, Lophospira tropidophora, Protarea 

 vetusta, and Streptelasma divaricams. Several feet farther up, 

 the top of the Madison bed consists of whitish limestone con- 

 taining Tetradium • it evidently is the source of some of the 

 pebbles in the Clinton limestone. 



Six miles north of Osgood, a mile and a half .northeast of 

 Napoleon, the clays and thin limestones at the top of the Madi- 

 son bed, exposed for a distance of at least 10 feet beneath the 

 Clinton, contain Rhynchotrema capax, Zygospira modesta, 

 and Plectamhonites sericea in addition to species already 

 mentioned. Rafinesquina alternata is rather abundant in the 

 white limestone at the top of the section. Streptelasma, divari- 

 cans is common at this horizon. Streptelasma rusticum is less 

 abundant. Hehertella near occidentalis and the Madison bed 

 form of Platystrophia are common here as elsewhere. 



A mile north of .Napoleon, a branch of Laugher y creek 

 exposes the top of the Madison bed, containing Platystrophia 

 acutilirita, and a large form of Plectamhonites, 25 mni in width 



